The Provider Primer Series: Mast cell activation syndrome (MCAS)

Mast cell activation syndrome (MCAS), also called mast cell activation disorder (MCAD), is an immunologic condition in which mast cells are aberrantly activated, resulting in inappropriate mediator release.

Presentation

  • MCAS can be responsible for chronic symptoms in multiple organs that cannot be attributed to another cause[vi].
  • Patients frequently receive diagnosis for a number of idiopathic conditions prior to correct diagnosis with MCAS[vi].
  • Mast cell activation syndrome is overwhelmingly a secondary condition. MCAS can be secondary to a number of conditions, including autoimmune diseases, connective tissue diseases, and atopic conditions[i].
  • The term “primary MCAS” refers to mediator release symptoms associated with mastocytosis[xvii] . However, the term “mastocytosis” generally conveys the understanding that both proliferation and mediator release symptoms are possible.
  • In idiopathic MCAS, no cause for symptoms can be identified[xvii] .
  • The presence of multiple mast cell patients in one family is not uncommon. A heritable gene has not yet been identified. Epigenetic mechanisms are suspected for transmission of mast cell disease to another generation[iv].
  • Approximately 75% of mast cell patients have at least one first degree relative with mast cell disease and not always the same subtype[ii]. For example, a mother may have MCAS, while one of her children has SM and the other has CM.

Diagnostic criteria

  • MCAS is a recently described diagnosis. In the absence of large studies, several groups have developed their own, sometimes conflicting, diagnostic criteria.
  • Differential diagnoses with potential to cause similar symptoms should be considered and excluded[iii].
  • The criteria most frequently used include those by a 2010 paper by Akin, Valent and Metcalfe[iii]; a 2011 paper by Molderings, Afrin and colleagues[iv]; and a 2013 paper by Castells and colleagues[v].
  • The criteria described in the 2011 paper by Molderings, Afrin and colleagues have been updated to include response to medication[vi].
  • Of note, a 2012 consensus proposal[x] was authored by a number of mast cell experts including Valent, Escribano, Castells, Akin and Metcalfe. It sees little practical use and is not generally accepted in the community.
  • The major sets of criteria listed above all include the following features:
    • Recurrent or chronic symptoms of mast cell activation
    • Objective evidence of excessive mast cell mediator release
    • Positive response to medications that inhibit action of mast cell mediators
  • Valent warns that in some cases, patients may not fulfill all criteria but still warrant treatment: “In many cases, only two or even one of these three criteria can be documented. In the case of typical symptoms, the provisional diagnosis of ‘possibly MCA/MCAS’ can be established, and in acute cases, immediate treatment should be introduced.”[vii]

Evidence of mediator release

  • Mast cells produce a multitude of mediators including tryptase, histamine, prostaglandin D2, leukotrienes C4, D4 and E4, heparin and chromogranin A[viii].
  • Serum tryptase and 24 hour urine testing for n-methylhistamine, prostaglandin D2, prostaglandin 9a,11b-F2 are frequently included in testing guidelines in literature (Castells 2013)[ix], (Akin 2010)[x], (Valent 2012)[xi].
  • It can be helpful to test for other mast cell mediators including 24 hour urine testing for leukotriene E4[xii]; plasma heparin[xiii]; and serum chromogranin A[xiv].
  • In most instances, elevation of a mediator must be present on two occasions[ix]. This helps to exclude situations of appropriate mast cell activation, such as infection or wound healing.
  • For patients with baseline tryptase level >15 ng/mL, elevation of tryptase above this baseline is only required on one occasion[viii].

Symptoms associated with mast cell activation

  • Mediator release causes a wide array of symptoms, including hypertension[xv], hypotension, hypertension, wheezing, itching, flushing, tachycardia, nausea, vomiting, diarrhea, constipation, headache, angioedema, fatigue, and neurologic symptoms[iv].
  • In a small MCAS cohort (18 patients), 17% had a history of anaphylaxis[xvii] . A larger data set is desirable.
  • Patients with history of anaphylaxis should be prescribed epinephrine autoinjectors[v]. If patient must be on a beta blocker, they should be prescribed a glucagon injector for use in the event of anaphylaxis[v].

Response to medications that inhibit action of mast cell mediators

  • Treatment of MCAS is complex and may require a number of medications. Second generation H1 antihistamines; H2 antihistamines; and mast cell stabilizers are mainstays of treatment[xvi].
  • Additional options include aspirin; anti-IgE; leukotriene blocker; and corticosteroids[xiii] .
  • First generation H1 antihistamines may be used for breakthrough symptoms[xiii] .
  • “An important point is that many different mediators may be involved in MCA-related symptoms so that the final conclusion the patient is not responding to antimediator therapy should only be drawn after having applied several different antimediator-type drugs[xiii] .
  • Inactive ingredients are often to blame for reaction to mast cell mediator focused medications. Many mast cell patients see benefit from having medications compounded[xvii].

Natural history

  • In one MCAS cohort of 18 patients, 33% had a complete (no unmanaged symptoms) response and 33% had a major (only one serious symptom) response after one year of mast cell treatment[xviii].
  • In another MCAS cohort of 135 patients, 51% demonstrated significant improvement, 11% had no obvious change in symptom severity and 38% experienced worsening symptoms[v]. (Author’s note: While described in an Afrin 2016[v] paper, the data from this cohort has not yet been published. Molderings is the principle investigator.

 

References

[i] Frieri M, et al. (2013). Mast cell activation syndrome: a review. Current Allergy and Asthma Reports, 13(1), 27-32.

[ii] Molderings GJ, et al. (2013). Familial occurrence of systemic mast cell activation disease. PLoS One, 8, e76241-24098785

[iii] Akin C, et al. (2010). Mast cell activation syndrome: proposed diagnostic criteria. J Allergy Clin Immunol, 126(6), 1099-1104.e4

[iv] Molderings GJ, et al. (2011). Mast cell activation disease: a concise practical guide for diagnostic workup and therapeutic options. Journal of Hematology & Oncology, 4(10), 10.1186/1756-8722-4-10

[v] Castells M, et al. (2013). Expanding spectrum of mast cell activation disorders: monoclonal and idiopathic mast cell activation syndromes. Clin Ther, 35(5), 548-562.

[vi] Afrin LB, et al. (2016). Often seen, rarely recognized: mast cell activation disease – a guide to diagnosis and therapeutic options. Annals of Medicine, 48(3).

[vii] Valent P. (2013). Mast cell activation syndromes: definition and classification. European Journal of Allergy and Clinical Immunology, 68(4), 417-424.

[viii] Theoharides TC, et al. (2012). Mast cells and inflammation. Biochimica et Biophysica Acta (BBA) – Molecular Basis of Disease, 1822(1), 21-33.

[ix] Picard M, et al. (2013). Expanding spectrum of mast cell activation disorders: monoclonal and idiopathic mast cell activation syndromes. Clinical Therapeutics, 35(5), 548-562.

[x] Akin C, et al. (2010). Mast cell activation syndrome: proposed diagnostic criteria. J Allergy Clin Immunol, 126(6), 1099-1104.e4

[xi] Valent P, et al. (2012). Definitions, criteria and global classification of mast cell disorders with special reference to mast cell activation syndromes: a consensus proposal. Int Arch Allergy Immunol, 157(3), 215-225.

[xii] Lueke AJ, et al. (2016). Analytical and clinical validation of an LC-MS/MS method for urine leukotriene E4: a marker of systemic mastocytosis. Clin Biochem, 49(13-14), 979-982.

[xiii] Vysniauskaite M, et al. (2015). Determination of plasma heparin level improves identification of systemic mast cell activation disease. PLoS One, 10(4), e0124912

[xiv] Zenker N, Afrin LB. (2015). Utilities of various mast cell mediators in diagnosing mast cell activation syndrome. Blood, 126(5174).

[xv] Shibao C, et al. (2005). Hyperadrenergic postural tachycardia syndrome in mast cell activation disorders. Hypertension, 45(3), 385-390.

[xvi] Cardet JC, et al. (2013). Immunology and clinical manifestations of non-clonal mast cell activation syndrome. Curr Allergy Asthma Rep, 13(1), 10-18.

[xvii] Afrin LB. “Presentation, diagnosis and management of mast cell activation syndrome.” In: Mast Cells. Edited by David B. Murray, Nova cience Publishers, Inc., 2013, 155-232.

[xviii] Hamilton MJ, et al. (2011). Mast cell activation syndrome: a newly recognized disorder with systemic clinical manifestations. Journal of Allergy and Clinical Immunology, 128(1), 147-152.e2

Mast cells in the GI tract: How many is too many? (Part One)

Let’s have a chat about the idea that 20 mast cells/hpf (high powered field) in gastrointestinal biopsy is higher than normal.

First, let’s review a few things.

The WHO diagnostic criteria for systemic mastocytosis are as follows:

Table 1: World Health Organization Criteria for Systemic Mastocytosis (2008)
  • Systemic mastocytosis is diagnosed in the presence of: 1 major and 1 minor criterion; or 3 minor criteria.
  • Biopsy specimens can be from any non-cutaneous organ (any organ that is not the skin).
Major criterion:
Multifocal, dense aggregates of mast cells (15 or more) detected in sections of bone marrow and confirmed by tryptase immunohistochemistry or other special stains:
Minor criterion:
1.       In biopsy section, more than 25% of mast cells in the infiltrate have atypical morphology, or, of all the mast cells in the smear, more than 25% are immature or atypical. (25% of the mast cells are shaped wrong.)
2.       Mast cells co-express CD117 with CD25 and/or CD2. (Mast cells show markers CD25 or CD2 on their outsides.)
3.       Detection of KIT point mutation at codon 816 in bone marrow, blood or other extracutaneous organs. (Positive for the CKIT D816V mutation.)
4.       Serum total tryptase persistently >20 ng/ml (not a valid criteria in cases of systemic mastocytosis with associated clonal non-hematologic mast-cell lineage disease). (Baseline serum tryptase over 20 ng/ml – baseline, not reaction.)

 

There are several different diagnostic algorithms floating around for mast cell activation syndrome (MCAS).  They are summarized here:

Table 2: Diagnostic algorithms for  mast cell activation syndrome (MCAS, also called mast cell activation disorder, MCAD)
  • Biopsy specimens can be from any non-cutaneous organ (any organ that is not the skin).
Molderings, Afrin 2011 Akin, Valent, Metcalfe 2010 Valent, Akin, Castells, Escribano, Metcalfe et al 2012
MCAD (mast cell activation disease, an  umbrella term including both MCAS and SM) is diagnosed if both major criteria, or one major criterion and one minor criterion, are present; following bone marrow biopsy, diagnosis is narrowed down to either SM or MCAS MCAS diagnosed if all criteria are met MCAS diagnosed if all criteria are met
Major Criteria
Multifocal of disseminated dense infiltrates of mast cells in bone marrow biopsies and/or in sections of other extracutaneous organ(s) (GI tract biopsies; CD117-, tryptase- and CD25- stained) Episodic symptoms consistent with mast cell mediator release affecting ≥2 organ systems evidenced as follows:

  • Skin: urticaria, angioedema, flushing
  • Gastrointestinal: nausea, vomiting, diarrhea, abdominal cramping
  • Cardiovascular: hypotensive syncope or near syncope, tachycardia
  • Respiratory: wheezing
  • Naso-ocular: conjunctival injection, pruritus, nasal stuffiness
Typical clinical symptoms
Unique constellation of clinical complaints as a result of a pathologically increased mast cell activity (mast cell mediator release symptom) A decrease in the frequency or severity or resolution of symptoms with antimediator therapy: H1– and H2-histamine receptor inverse agonists, antileukotriene medications (cysteinyl leukotriene receptor blockers or 5-lipoxygenase inhibitor), or mast cell stabilizers (cromolyn sodium) Increase in serum total tryptase by at least 20% above baseline plus 2 ng/ml during or within 4 h after a symptomatic period
  Evidence of an increase in a validated urinary or serum marker of mast cell activation: documentation of an increase of the marker to greater than the patient’s baseline value during a symptomatic period on ≥2 occasions or, if baseline tryptase levels are persistently >15 ng, documentation of an increase of the tryptase level above baseline value on 1 occasion. Total serum tryptase level is recommended as the marker of choice; less specific (also from basophils) are 24-hour urine histamine metabolites or PGD2 or its metabolite 11-β-prostaglandin F2. Response of clinical symptoms to histamine receptor blockers or MC-targeting agents e.g. cromolyn
  Rule out primary and secondary causes of mast cell activation and well-defined clinical idiopathic entities
Minor Criteria
Mast cells in bone marrow or other extracutaneous organ(s) show an abnormal morphology (>25%) in bone marrow smears or in histologies
Mast cells in bone marrow express CD2 and/or CD25
Detection of genetic changes in mast cells from blood, bone marrow or extracutaneous organs for which an impact on the state of activity of affected mast cells in terms of an increased activity has been proved
Evidence of a pathologically increased release of mast cell mediators by determination of the content of:

  • Tryptase in blood
  • N-methylhistamine in urine
  • Heparin in blood
  • Chromogranin A in blood
  • Other mast cell specific mediators (leukotrienes, PGD2)

 

Additionally, a questionnaire (found here: http://www.wjgnet.com/2218-6204/abstract/v3/i1/1.htm) designed to assess the likelihood of mast cell activation disease (MCAS or SM) in a patient was published in 2014 by Lawrence Afrin.  It assigns numerical values to various findings, such as mediator elevation, symptoms, clinical findings, and biopsy features.

The criteria for systemic mastocytosis can be met with a gastrointestinal biopsy showing the features listed above in Table 1.  So if you have gastrointestinal scopes and your biopsy shows mast cells with the features listed in Table 1, then that contributes to receiving a diagnosis of SM.  If you meet some of the criteria but not all of them, with a GI biopsy or otherwise, then you receive a diagnosis of monoclonal mast cell activation syndrome (MMAS), which is like a pre-SM.

A common adage in the mast cell community is that having 20 or more mast cells in a high powered field (hpf, what you see when you look through a microscope with high magnification) is diagnostic for mast cell activation syndrome.

In 2006, a paper was published called “Mastocytic enterocolitis: Increased mucosal mast cells in chronic intractable diarrhea.” This paper detailed a study that quantified the mast cells in biopsies of duodenum (small intestine) and colon in patients with chronic diarrhea that resisted treatment. These counts were then compared to patients who had other conditions that caused chronic diarrhea, and to some control subjects that had no GI symptoms.

Table 3: Average mast cell count per hpf in colon and duodenum (Jakate 2006)
Group Average mast cell count in colon and duodenum
Healthy control group 13.3 ± 3.5
Inflammatory GI disease control group 12.4 ± 2.3
Intractible chronic diarrhea group 25.7 ± 4.5

 

The average mast cell count in the healthy control group was 13.3/hpf.  (See Table 3 for details.) Two standard deviations from this value is approximately 20/hpf.  Two standard deviations (SD) is a statistical mechanism that allows for variation in the patient, sample or test procedure.  It is common to round to an even number.

The patients in this group were not evaluated for typical mast cell symptoms.  No information is provided regarding history of allergic or atopic disease. This paper is the origin of the idea that more than 20 mast cells/hpf in the gastrointestinal tract is considered higher than normal.

 

References:

Jakate S, et al. Mastocytic enterocolitis: Increased mucosal mast cells in chronic intractable diarrhea.  Arch Pathol Lab Med 2006; 130 (3): 362-367.

Akhavein AM, et al. Allergic mastocytic gastroenteritis and colitis: An unexplained etiology in chronic abdominal pain and gastrointestinal dysmotility. Gastroenterology Research and Practice (2012): Article ID 950582.

Martinez C, et al. Diarrhoea-predominant irritable bowel syndrome: an organic disorder with structural abnormalities in the jejunal epithelial barrier. Gut 2013; 62: 1160-1168,

Sethi A, et al. Performing colonic mast cell counts in patients with chronic diarrhea of unknown etiology has limited diagnostic use. Arch Pathol Lab Med 2015; 139 (2): 225-232.

Doyle LA, et al. A clinicopathologic study of 24 cases of systemic mastocytosis involving the gastrointestinal tract and assessment of mucosal mast cell density in irritable bowel syndrome and asymptomatic patients. Am J Surg Pathol 2014; 38 (6): 832-843.

Ramsay DB, et al. Mast cells in gastrointestinal disease. Gastroenterology & Hepatology 2010; 6 (12): 772-777.

Zare-Mirzaie A, et al. Analysis of colonic mucosa mast cell count in patients with chronic diarrhea. Saudi J Gatroenterol 2012; 18 (5): 322-326.

Walker MM, et al. Duodenal mastocytosis, eosinophilia and intraepithelial lymphocytosis as possible disease markers in the irritable bowel syndrome and functional dyspepsia. Aliment Pharmacol Ther 2009; 29 (7): 765-773.

Hahn HP, Hornick JL. Immunoreactivity for CD25 in Gastrointestinal Mucosal Mast Cells is Specific for Systemic Mastocytosis. American Journal of Surgical Pathology 2007; 31(11): 1669-1676.

Vivinus-Nebot M, et al. Functional bowel symptoms in quiescent inflammatory bowel diseases : role of epithelial barrier disruption and low-grade inflammation. Gut 2014; 63: 744-752.

Minnei F, et al. Chronic urticaria is associated with mast cell infiltration in the gastroduodenal mucosa. Virchows Arch 2006; 448(3): 262-8.

Hamilton MJ, et al. Mast cell activation syndrome: A newly recognized disorder with systemic clinical manifestations. J Allergy Clin Immunol 2011; 128: 147-152.

Barbara G, et al. Activated mast cells in proximity to colonic nerves correlate with abdominal pain in irritable bowel syndrome. Gastroenterology 2004; 126(3): 693-702.

Guilarte M, et al. Diarrhoea-predominant IBS patients show mast cell activation and hyperplasia in the jejunum. Gut 2007; 56: 203-209.

Dunlop SP, et al.  Age related decline in rectal mucosal lymphocytes and mast cells. European Journal of Gastroenterology and Hepatology 2004; 16(10): 1011-1015.

Afrin LB, Molderings GJ. A concise, practical guide to diagnostic assessment for mast cell activation disease. World J Hematol 2014; 3 (1): 1-17.

Molderings GJ, et al. Mast cell activation disease: a concise, practical guide to diagnostic workup and therapeutic options. J Hematol Oncol 2011; 4 (10).

Akin C, et al. Mast cell activation syndrome: proposed diagnostic criteria. J Allergy Clin Immunol 2010; 126 (6): 1099-1104.

Valent P, et al. Definitions, criteria and global classification of mast cell disorders with special reference to mast cell activation syndromes: a consensus proposal. Int Arch Allergy Immunol 2012: 157 (3): 215-225.

 

 

 

Off the reservation

I am not sure how this is possible, but I have actually never interacted with Brynn Duncan. For those who don’t know, she is one of our young adult mast cell patients. She is very photogenic and seems lovely. She writes a blog about her life and her health struggles. Recently, she has been the subject of some articles on various sites (Buzzfeed, among them) and so I have read about her a lot in the last few weeks.

Today, the American Academy of Allergy, Asthma & Immunology (AAAAI) posted a link to an article in Cosmo about Brynn. (Link here: http://bit.ly/1FvAlUN) In the way that often happens when you have a relatively new, complex medical condition, people began speculating in the comments. Some had questions about her diagnosis (specifically, the criteria used, and whether she met them).

One of the better aspects of rare disease communities is that when the internet feels like doubting the disabling and life altering nature of your condition, there are plenty of people to have your back. The mast cell community showed up in the comments and made their reality known. Mast cell patients know what it is to be doubted, and to suffer for years because of that doubt. They felt that people were doubting Brynn and they reacted in the way they felt best supported her.

Also, please keep in mind that sick people who share their stories for awareness are people. They are people with boundaries and rights to privacy. It is very possible that all of the salient details are not captured in public media.

But there is another layer here that needs to be addressed. And that is this: what exactly is MCAS, and how do you know if you have it? And if you test negative, do you still have it? And that is a conversation that we need to have both inside the community, for patients, and outside the community, for providers to be able to treat mast cell patients effectively.

If you go through the peer reviewed literature, there are multiple sets of diagnostic criteria for MCAS. This is not helpful, but is pretty common for newer diagnoses. Specifically, it is not unusual for clinical entities that don’t have WHO or ICD diagnostic criteria. Clinicians group people together based upon sets of clinical findings, and sometimes lab findings, and uses those as markers for this previously undescribed entity. Doctors and scientists disagree with each other a lot, and so you develop multiple schools of thought on what constitutes X diagnosis. So you potentially multiple distinct groups of patients with the same name attached to their diagnosis. It is very confusing, and can really complicate things when you try to identify exactly what commonalities unify these people.

One of the commentors mentioned that he felt a well-known doctor in the mast cell community used very lax criteria to diagnose MCAS, and in particular, did not meet the criteria published in JACI (J Allergy Clin Immunol). For clarity when referencing my post on differing MCAS criteria, the 2010 Akin and the 2012 Akin, Valent, et al, Consensus proposal, were published in JACI. The Afrin and Molderings 2011 was published in J Hematol Oncol. Here is a comparison of published diagnostic criteria for MCAS:

Gerhard J Molderings, Stefan Brettner, Jürgen Homann, and Lawrence B Afrin. Mast cell activation disease: a concise practical guide for diagnostic workup and therapeutic options. J Hematol Oncol. 2011; 4: 10.

Cem Akin, MD, PhD, Peter Valent, MD, Dean D. Metcalfe, MD. Mast cell activation syndrome: Proposed diagnostic criteria. Volume 126, Issue 6, December 2010, Pages 1099–1104.e4 Peter Valent, Cem Akin, Michel Arock, Knut Brockow, Joseph H. Butterfield,

Melody C. Carter, Mariana Castells, Luis Escribano, Karin Hartmann, Philip Lieberman, Boguslaw Nedoszytko, Alberto Orfao, Lawrence B. Schwartz, Karl Sotlar,

Wolfgang R. Sperr, Massimo Triggiani, Rudolf Valenta, Hans-Peter Horny,

Dean D. Metcalfe. Definitions, Criteria and Global Classification of Mast Cell Disorders with Special Reference to Mast Cell Activation Syndromes: A Consensus Proposal. Int Arch Allergy Immunol 2012;157:215–225.

MCAD (umbrella term including both MCAS and SM) diagnosed if both major criteria, or one major criterion and one minor criterion, are present; following bone marrow biopsy, diagnosis is narrowed down to either SM or MCAS MCAS diagnosed if all criteria are met MCAS diagnosed if all criteria are met

Major Criteria

Multifocal of disseminated dense infiltrates of mast cells in bone marrow biopsies and/or in sections of other extracutaneous organ(s) (GI tract biopsies; CD117-, tryptase- and CD25- stained)
Episodic symptoms consistent with mast cell mediator release affecting ≥2 organ systems evidenced as follows:
  1. Skin: urticaria, angioedema, flushing
  2. Gastrointestinal: nausea, vomiting, diarrhea, abdominal cramping
  3. Cardiovascular: hypotensive syncope or near syncope, tachycardia
  4. Respiratory: wheezing
  5. Naso-ocular: conjunctival injection, pruritus, nasal stuffiness
Typical clinical symptoms
Unique constellation of clinical complaints as a result of a pathologically increased mast cell activity (mast cell mediator release symptom) A decrease in the frequency or severity or resolution of symptoms with antimediator therapy: H1– and H2-histamine receptor inverse agonists, antileukotriene medications (cysteinyl leukotriene receptor blockers or 5-lipoxygenase inhibitor), or mast cell stabilizers (cromolyn sodium) Increase in serum total tryptase by at least 20% above baseline plus 2 ng/ml during or within 4 h after a symptomatic period
Evidence of an increase in a validated urinary or serum marker of mast cell activation: documentation of an increase of the marker to greater than the patient’s baseline value during a symptomatic period on ≥2 occasions or, if baseline tryptase levels are persistently >15 ng, documentation of an increase of the tryptase level above baseline value on 1 occasion. Total serum tryptase level is recommended as the marker of choice; less specific (also from basophils) are 24-hour urine histamine metabolites or PGD2 or its metabolite 11-β-prostaglandin F2. Response of clinical symptoms to histamine receptor blockers or MC-targeting agents e.g. cromolyn
Rule out primary and secondary causes of mast cell activation and well-defined clinical idiopathic entities

Minor Criteria

Mast cells in bone marrow or other extracutaneous organ(s) show an abnormal morphology (>25%) in bone marrow smears or in histologies
Mast cells in bone marrow express CD2 and/or CD25
Detection of genetic changes in mast cells from blood, bone marrow or extracutaneous organs for which an impact on the state of activity of affected mast cells in terms of an increased activity has been proved
Evidence of a pathologically increased release of mast cell mediators by determination of the content of:

  1. Tryptase in blood
  2. N-methylhistamine in urine
  3. Heparin in blood
  4. Chromogranin A in blood
  5. Other mast cell specific mediators (leukotrienes, PGD2)

 

Additionally, there are differences of opinion on whether or not having a primary mast cell disease (mastocytosis, etc) disqualifies you from having MCAS. Most agree that MCAS can be secondary to another condition, including a number of autoimmune conditions. However, whether allergic type symptoms accompanying systemic mastocytosis, for example, qualifies as MCAS is still not agreed upon. Some feel that these symptoms are inherently part of the SM diagnosis, and that MCAS is a diagnosis of exclusion. Others feel SM refers to a proliferative condition, whereas MCAS refers to the inappropriate allergic response. It is a mess for patients, caregivers, researchers, doctors familiar with the condition and doctors who aren’t.

Compounding this issue is the fact that the test most doctors are likely to be familiar with (tryptase) often yields results in normal range. Sometimes, patients experiencing flagrant anaphylaxis under the banner of MCAS will not even demonstrate the 2ng/ml + 2% above baseline that some experts consider indicative of degranulation. Tryptase, like all other mediator tests used to diagnose MCAS, is time sensitive. But sometimes one normal tryptase is enough for doctors to dismiss MCAS as a possible diagnosis (for the record, about 15% of SM patients also have normal tryptase levels).

But then how do you know it’s MCAS and not something else? Therein lies the crux. I think for patients who are experiencing unmistakable anaphylaxis resolved by epinephrine, it is a smaller jump of logic to land on MCAS. But what about so many mast cell patients with non-specific symptoms and negative test results? Do they all have MCAS?

The answer is that we don’t know, and furthermore, that it depends heavily on how you define it. Many doctors use response to typical mast cell medications (antihistamines, stabilizers) as proof of MCAS. But mast cells are involved in so many types of inflammation that treating mast cell degranulation is likely to help with a number of other conditions as well. If the patient is improving, I think most doctors are inclined to continue treatment while still looking for other possible causes. But what if the patient doesn’t improve? What if they get worse?

Diagnoses of exclusion can be dangerous in that many times it is eventually proven wrong. Treating for the wrong disease can be disastrous – both in the potential adverse effects and in the potential to mask the true diagnosis indefinitely. I understand the reluctance to operate under an unusual diagnosis with no empirical proof that it is the right one.

However, there is also a long precedent in medicine in treating “like” diseases with treatments defined for its look alike condition. For example, treating someone who “looks” like they have lupus, as regards symptoms or borderline laboratory findings, with lupus medications is not unusual. And I think that this needs to be considered. Because at the end of the day, MCAS patients are sick. These are people who often have severe, life threatening anaphylactic episodes and daily symptoms that affect their ability to function in the world. Making an educated guess and proceeding cautiously is a well established practice in medicine.

All biomarkers were once unknown. Medicine, and science, are living entities that evolve over time. Eventually causes for diseases are identified and tests developed, and then better tests. This is just another example of not being able to detect well something we haven’t known for very long we needed to look for.

In spite of these difficulties, I think it’s important for clinicians not to lose sight of this fact: MCAS is real. And it’s quite possible that it’s not as rare as we think. One researcher has estimated that MCAS associated mutations may occur in over 5% of the population (Molderings 2014). If this bears fruit, then these people in your office needing help are only the first wave of a growing population that is allergic to the world. We are off the reservation right now, but these people still need help.

 

References:

G.J. Molderings. The genetic basis of mast cell activation disease – looking through a glass darkly. Critical Reviews in Oncology/Hematology 2014.

G.J. Molderings, B. Haenisch, M. Bogdanow, R. Fimmers, M.M. Nöthen. Familial occurrence of systemic mast cell activation disease. PLoS One, 8 (2013), p. e76241

Gerhard J Molderings, Stefan Brettner, Jürgen Homann, and Lawrence B Afrin. Mast cell activation disease: a concise practical guide for diagnostic workup and therapeutic options. J Hematol Oncol. 2011; 4: 10.

Cem Akin, MD, PhD, Peter Valent, MD, Dean D. Metcalfe, MD. Mast cell activation syndrome: Proposed diagnostic criteria. Volume 126, Issue 6, December 2010, Pages 1099–1104.e4

Peter Valent, Cem Akin, Michel Arock, Knut Brockow, Joseph H. Butterfield, Melody C. Carter, Mariana Castells, Luis Escribano, Karin Hartmann, Philip Lieberman, Boguslaw Nedoszytko, Alberto Orfao, Lawrence B. Schwartz, Karl Sotlar, Wolfgang R. Sperr, Massimo Triggiani, Rudolf Valenta, Hans-Peter Horny, Dean D. Metcalfe. Definitions, Criteria and Global Classification of Mast Cell Disorders with Special Reference to Mast Cell Activation Syndromes: A Consensus Proposal. Int Arch Allergy Immunol 2012;157:215–225.

Juan-Carlos Cardet, Maria C. Castells, and Matthew J. Hamilton. Immunology and Clinical Manifestations of Non-Clonal Mast Cell Activation Syndrome. Curr Allergy Asthma Rep. Feb 2013; 13(1): 10–18.

Britta Haenisch, Markus M. Nothen and Gerhard J. Molderings. Systemic mast cell activation disease: the role of molecular genetic alterations in pathogenesis, heritability and diagnostics. Immunology 2012, 137, 197–205.

Matthieu Picard, Pedro Giavina-Bianchi, Veronica Mezzano, Mariana Castells. Expanding Spectrum of Mast Cell Activation Disorders: Monoclonal and Idiopathic Mast Cell Activation Syndromes. Clinical Therapeutics, Volume 35, Issue 5, May 2013, Pages 548–562.

 

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Progression of mast cell diseases (Part 4)

If ISM is life threatening, why is not considered as dangerous as ASM or MCL?

ISM is not life threatening. Anaphylaxis is life threatening. They are not the same. Many people with ISM never experience anaphylaxis. ISM can make anaphylaxis more dangerous, but ISM is not the same as anaphylaxis. Outside of anaphylaxis, ISM is not life threatening.

“Indolent systemic mastocytosis (SM) patients have a varied clinical presentation, ranging from predominantly cutaneous symptoms to recurrent systemic symptoms (eg, flushing, palpitations, dyspepsia, diarrhea, bone pain) that can be severe and potentially life threatening (anaphylaxis.)” (Pardanini 2013)

 

Is MCAS more or less dangerous than ISM?

“From a clinical standpoint, MMAS and MCAS share many similarities with systemic mastocytosis (SM), a primary disorder of mast cells in which patients experience symptoms ranging from pruritus and flushing to anaphylaxis.” (Picard 2013)

Again, the real danger here is anaphylaxis rather than these entities themselves. Statistically, the numbers don’t have a lot of uniformity regarding frequency of anaphylaxis in SM, what constitutes a severe reaction, and so on. Additionally, there are multiple definitions of MCAS and how that is distinguished from IA, which is really important to understanding the true frequency of anaphylaxis in MCAS. However, the data currently shows a trend of anaphylaxis being less common in MCAS than in SM. Still, it is important to realize that this may be due to less research being available on MCAS than mastocytosis.

“In our cohort 3 [MCAS] patients (17%) had a history of anaphylaxis. These patients were included in our cohort because they had primary symptoms characteristic of MCAS that responded to medications and had other laboratory evidence of MC mediator release…There likely exists a spectrum of disease for MCAS in which the more severe form includes anaphylaxis and a spectrum of IA in which a form includes MCAS symptoms.” (Hamilton 2011)

It is well known that people with mastocytosis are more likely to experience anaphylaxis than the general public. In adults with any type of mastocytosis, 49% experience anaphylaxis. Patients with systemic mastocytosis were more likely to anaphylax than those with cutaneous mastocytosis. In adults, 48% of the anaphylactic reactions were severe, with 38% causing unconsciousness. 60% of those reactions were Grade III anaphylaxis. (Brockow 2008)

“In 4 of the 137 [SM] patients (3%), severe life-threatening anaphylaxis resulting in a severe handicap with or without transient or permanent disability occurred.” (Wimazal 2012)

“Prolonged hypotension following anaphylaxis and cerebral hypoxia were identified as major factors leading to a substantial handicap, clinical deterioration or even death in these patients.” (Wimazal 2012)

“However, in both patients in whom recurrent life-threatening anaphylaxis was recorded, the smoldering subtype of SM with a huge burden of MCs was diagnosed, whereas most patients in whom only one documented severe life-threatening event had occurred were found to have low-grade SM with a low burden of MCs.” (Wimazal 2012)

“Thirty-six [SM] patients (43%) had had at least one episode of an anaphylactic reaction. The clinical courses of the reactions were usually severe and patients often presented with syncope attacks (72%). Most patients reacted after hymenoptera venom stings (19/36; 53%). In 39% (14/36), a clear etiology could not be determined. While males and females were equally frequent among the patients with SM, anaphylaxis patients showed a male predominance (61%). Anaphylactic reactions occurred more frequently in patients without cutaneous engagement. The rate of allergy sensitization was significantly higher in SM patients with anaphylaxis as compared with non-anaphylaxis SM patients, 70% vs. 23%, respectively.” (Gulen 2014)

 

Does an elevated GI mast cell count tract (in the absence of aberrant receptors, clustering or spindled mast cells) indicate MCAS or SM?

“Our immunohistochemical analysis led us to the conclusion that there was no significant difference between the numbers of intestinal mucosal MCs in our patients with MCAS and our reference standard. We recognize that there is currently no consensus for what constitutes a normal number of MCs in the various intestinal tissues. We therefore chose data from a recently published study by one of the authors to be the reference standard. In this study normal numbers of MCs were tabulated for each tissue site. Although we did not find appreciably increased numbers of MCs or abnormal morphology, it is possible that patients with MCAS have a different threshold for MC activation and differentially release MC mediators on activation or that peripheral tissues have an abnormal response to these mediators. We also recognize that a population of patients with chronic diarrhea has been described and labeled as having mastocytic enterocolitis. These patients had a greater number of MCs per hpf in duodenal and colon biopsy specimens compared with the control population (>20 vs 13 MCs/hpf). We were not able to verify this observation in our cohort because many of our control population biopsy specimens had more than 20 MCs/hpf.” (Hamilton 2011)

 

What is the relationship between CM and MCAD (including SM and MCAS)?

“[M]ost patients with adult-onset MIS [mastocytosis in the skin (commonly called cutaneous mastocytosis,CM)] have demonstrable bone marrow (BM) involvement with clonal mast cells when modern-era diagnostic tools are used, in most instances, satisfying WHO diagnostic criteria for SM. While historical series of patients with MIS revealed an 18% to 50% prevalence of systemic involvement based on conventional histologic criteria, more modern series suggest that only a minority of adult patients have skin-limited disease. Further, approximately 50% of adults with apparent skin-limited mastocytosis may have a clonal BM mast cell infiltrate that falls short of the diagnostic threshold for SM (satisfies major criterion only or only 1 or 2 minor criteria), suggesting prediagnostic or early stage of ISM.” (Pardanini 2013)

“The relationship between systemic MCAD and cutaneous mastocytosis (CM, synonyms: paediatric or childhood onset mastocytosis) remains unclear. Early studies suggested that CM and systemic MCAD were separate disease entities, because the majority of CM patients were found to lack mutations of the tyrosine kinase KITgene. However, subsequent studies have demonstrated that the frequency of clonal KIT mutations is similar in patients with CM, SM and MCAS, and that they are present in up to 86% of patients from each diagnostic group.” (Haenisch 2012)

“Interestingly, in contrast to adult-onset systemic MCAD, more than 50% of paediatric cases of cutaneous mastocytosis appear to enter long-term remission spontaneously, though whether such remissions are permanent or relapse in adulthood as systemic MCAD is unknown.” (Haenisch 2012)

“In contrast, most adults with CM have an underlying SM and should undergo a bone marrow biopsy regardless of the presence of associated systemic symptoms of mediator release. Conversely, 80% of SM patients have cutaneous disease that manifests as urticaria pigmentosa. In contrast, patients with MMAS and MCAS never have CM, and patients with ASM or MCL frequently lack CM.” (Picard 2013)

 

References:

Juan-Carlos Cardet, Maria C. Castells, and Matthew J. Hamilton. Immunology and Clinical Manifestations of Non-Clonal Mast Cell Activation Syndrome. Curr Allergy Asthma Rep. Feb 2013; 13(1): 10–18.

Britta Haenisch, Markus M. Nothen and Gerhard J. Molderings. Systemic mast cell activation disease: the role of molecular genetic alterations in pathogenesis, heritability and diagnostics. Immunology 2012, 137, 197–205.

Animesh Pardanani. How I treat patients with indolent and smoldering mastocytosis (rare conditions but difficult to manage.) April 18, 2013; Blood: 121 (16).

Matthieu Picard, Pedro Giavina-Bianchi, Veronica Mezzano, Mariana Castells. Expanding Spectrum of Mast Cell Activation Disorders: Monoclonal and Idiopathic Mast Cell Activation Syndromes. Clinical Therapeutics, Volume 35, Issue 5, May 2013, Pages 548–562.

Gerhard J Molderings, Stefan Brettner, Jürgen Homann, Lawrence B Afrin. Mast cell activation disease: a concise practical guide for diagnostic workup and therapeutic options. Journal of Hematology & Oncology 2011, 4:10.

Brockow, C. Jofer, H. Behrendt and J. Ring. Anaphylaxis in patients with mastocytosis: a study on history, clinical features and risk factors in 120 patients. Allergy, Volume 63, Issue 2, pages 226–232, February 2008.

Wimazal F., Geissler P., Shnawa P., Sperr W.R., Valent P. Severe Life-Threatening or Disabling Anaphylaxis in Patients with Systemic Mastocytosis: A Single-Center Experience. Int Arch Allergy Immunol 2012; 157: 399–405.

Gülen, H. Hägglund, B. Dahlén and G. Nilsson. High prevalence of anaphylaxis in patients with systemic mastocytosis – a single-centre experience. Clinical & Experimental Allergy, Volume 44, Issue 1, pages 121–129, January 2014.

 

 

 

Progression of mast cell diseases (Part 3)

What causes aberrant mediator release in mast cell activation diseases (including MCAS and SM)?

“Selective release of mediators during mast cell activation may be accomplished in three important and possibly interrelated ways. One is by activation via one of the mast cell’s non-IgE receptors, for instance, through the activation of the IL-1 receptor… Another way in which mast cells may selectively activate is through ‘piecemeal’ release of mediators stored in the secretory granules (such as histamine and serotonin)… Lastly, downstream signaling pathways may affect mast cell activation… Differential activation of mast cells in any of these ways may clinically manifest as nc-MCAS.” (Cardet 2013)

“It is also conceivable that mast cells in this group of patients may aberrantly possess a lower threshold to release mediators… It is also conceivable that patients with nc-MCAS are symptomatic because of an abnormal tissue response to physiologically appropriate release of MC mediators.” (Cardet 2013)

“The mutations underlying systemic MCAD drive aberrant mediator production/release with or without readily histologically detectable mast cell accumulation. Mast cell accumulation is due predominantly to a decrease in mast cell apoptosis (refs 30,31 and further references therein). On a limited scale, it is also due to an increase in proliferation.” (Haenisch 2012)

 

Do all SM patients have elevated n-methylhistamine and prostaglandin F2a?

71% had elevated urinary histamine in 24 hr test; 81% had elevated urinary n-methylhistamine in 24 hr test; 75% had elevated urinary PGF2a in 24 hr test. (Lim 2009)

 

If my tryptase is normal, does that mean I don’t have SM?

In patients tested, 96% had elevated tryptase over 11.5 ng/ml. (Lim 2009)

“20% to 30% of SM patients have serum tryptase levels below the WHO-defined threshold of 20 ng/mL (sensitivity 80%, specificity 98%).” (Pardanini 2013)

 

If my blood test for the D816V mutation is negative, I definitely don’t have it, right?

“The sensitivity of KITD816V detection in peripheral blood is suboptimal, and tests for non-KITD816V mutation screening may not be readily available.” (Pardanini 2013)

“I prefer using DNA from BM aspirate for KITD816V screening given the low sensitivity of peripheral blood in this regard… Using this approach, we found 78% of ISM patients to harbor KITD816V.” (Pardanini 2013)

“Although, the sensitivity of KITD816V detection may be higher when using sorted or purified mast cells, this option is not routinely available. Consequently, the inability to detect KITD816V in peripheral blood does not exclude SM [].” (Pardanini 2013)

 

How often do SM patients not meet the major diagnostic criteria (mast cell aggregates)?

“Attempts at validating the WHO diagnostic criteria reveal that approximately 20% of ISM patients lack mast cell clusters in the BM and approximately 30% exhibit a serum tryptase level < 20 ng/mL.” (Sanchez 2011)

 

Is MCAS the same as HIT (histamine intolerance)?

“[S]ome have proposed that a deficiency in the enzymes responsible for histamine metabolism, diamine oxidase (DAO) and histamine N-methyltransferase, leads to excess levels of histamine and therefore histamine intolerance, with clinical manifestations not unlike those described for nc-MCAS… There is no scientific literature to support their relevance to nc-MCAS.” (Cardet 2013)

 

Are MCAS patients usually positive for the three most commonly tested mediators (tryptase, n-methylhistamine, PGD2?)

“Although all of our patients with MCAS had a positive test result for at least 1 MC mediator, only 33%, 56%, and 44% of the patients had positive test results for tryptase, histamine, and PGD2, respectively.” (Hamilton 2011)

 

Will my MCAS symptoms ever get better?

“Most patients with MCAS in our cohort who were treated with anti-MC mediator medications responded dramatically. After an average of 4.6 years of MC-related symptoms, 66% of the patients with MCAS achieved a complete or major regression in symptoms to MCAS treatment.” (Hamilton 2011)

“It is important to mention that no defining characteristics (eg, presence of allergies or history of anaphylaxis) could be identified that distinguished those who had a complete regression in symptoms versus those who did not.” (Hamilton 2011)

“The most impressive treatment responses were for abdominal pain (14/17 of the patients who initially had the symptom responded), headache (12/15), poor concentration and memory (7/12), and diarrhea (9/12); there was a more modest response to flushing (6/16). We also found that all but 1 of our patients with MCAS had a sustained response to anti-MC mediator medications. Patients in our cohort were followed for an average of 2.8 years (range, 1-4 years).” (Hamilton 2011)

“In patients with MCAS the rate of response to antimediator therapy is rather good, with 33% showing complete response, 33% a major response, and 33% a minor response after 1 year of treatment.” (Picard 2013)

 

How prevalent is MCAS?

“MCAS seems to be a more common disorder. Evidence has been presented that MCAS may be an underlying cause of various clinical presentations, e.g. in subsets of patients with fibromyalgia and irritable bowel syndrome. Hence, the prevalence of MCAS is likely to lie within the single-digit percentage range.” (Haenisch 2012)

“Mast cell activation disease in general has long been thought to be rare. However, although SM and MCL as defined by the WHO criteria are truly rare, recent findings suggest MCAS is a fairly common disorder. Evidence has been presented for a causal involvement of pathologically active mast cells not only in the pathogenesis of SM and MCAS but also in the etiology of idiopathic anaphylaxis, interstitial cystitis, some subsets of fibromyalgia and some subsets of irritable bowel syndrome.” (Molderings 2011)

 

References:

Juan-Carlos Cardet, Maria C. Castells, and Matthew J. Hamilton. Immunology and Clinical Manifestations of Non-Clonal Mast Cell Activation Syndrome. Curr Allergy Asthma Rep. Feb 2013; 13(1): 10–18.

LimKH, TefferiA, LashoTL, et al. Systemic mastocytosis in 342 consecutive adults: survival studies and prognostic factors. Blood 2009; 113(23): 5727-5736.

Britta Haenisch, Markus M. Nothen and Gerhard J. Molderings. Systemic mast cell activation disease: the role of molecular genetic alterations in pathogenesis, heritability and diagnostics. Immunology 2012, 137, 197–205.

Animesh Pardanani. How I treat patients with indolent and smoldering mastocytosis (rare conditions but difficult to manage.) April 18, 2013; Blood: 121 (16).

Matthieu Picard, Pedro Giavina-Bianchi, Veronica Mezzano, Mariana Castells. Expanding Spectrum of Mast Cell Activation Disorders: Monoclonal and Idiopathic Mast Cell Activation Syndromes. Clinical Therapeutics, Volume 35, Issue 5, May 2013, Pages 548–562.

Gerhard J Molderings, Stefan Brettner, Jürgen Homann, Lawrence B Afrin. Mast cell activation disease: a concise practical guide for diagnostic workup and therapeutic options. Journal of Hematology & Oncology 2011, 4:10.

 

MCAS: Respiratory symptoms

Pharyngeal (throat) symptoms are quite common in MCAS and as usual, highly variable. Burning, painful, and irritated throats are frequently reported, and often automatically treated as viral infection or Strep throat, with no culture or negative culture. This pain can be chronic or intermittent. A chronic tickle in the throat or need to clear the throat is often present. Sinus congestion can lead to postnasal drip.

Sometimes MCAS reactions are localized to the throat, inhibiting ability to swallow or sometimes even breathe. This symptom is due to angioedema, and if breathing difficulty is observed, emergency treatment with epinephrine is required.

The most frequently noted lower respiratory symptom is a low level difficulty of breathing. This often presents as occasional wheezing, or feeling like you can’t get a deep breath. Patients rarely have severe wheezing, though it does sometimes happen. Chest x-ray and pulmonary function testing are usually normal.

Chronic non-productive cough affects a small portion of MCAS patients. They are often diagnosed with reactive airway disease for lack of a better explanation. Prostaglandin D2 is a potent bronchoconstrictor, approximately 10 times more potent than histamine, and is responsible in part for respiratory symptoms.

Mast cells have been implicated a variety of pulmonary pathologies, including COPD and pulmonary hypertension. Allergic asthma is not uncommon in MCAS patients and this population often reports successful treatment with Xolair.

References:

Afrin, Lawrence B. Presentation, diagnosis and management of mast cell activation syndrome. 2013. Mast cells.

Anand P, et al. Mast cells: an expanding pathophysiological role from allergy to other disorders. Naunyn-Schiedeberg’s Arch. Pharmacol. 2012 May.

 

MCAS: Pain

Pain is an unfortunate fact of life with MCAS. Muscle fatigue and weakness are common complaints, but myositis and rhabdomyolysis are rare. Some patients have elevated creatine kinase and/or aldolase, but have no related symptoms.

Bone pain is frequently reported with MCAS. Osteopenia and osteoporosis are common findings. Focal osteosclerosis is also sometimes found, but less frequently. Joints are often painful, which can lead to diagnoses of osteoarthritis, seronegative rheumatoid arthritis, fibromyalgia and polymyalgia rheumatica. Pain can migrate and is often poorly localized. Patients often feel pain in joints, bones and soft tissues, sometimes inconsistently.

Mast cells have been implicated in several pain disorders. Chronic lower back pain has been hypothesized to be related to mast cell activation for over a decade. Complex regional pain syndrome Type I, formerly known as reflex sympathetic dystrophy (RSD) and reflex neurovascular dystrophy (RND), is the most painful long term condition described. It is marked by neurogenic inflammation (nervous system swelling), sensitization of pain receptors and circulatory problems that cause swelling and color changes. It can affect any part of the body. Mast cells have been linked to the inflammatory response seen in CRPS patients.

Neurons with noradrenaline, serotonin and opioidergic receptors inhibit transmission of pain signals. (This is why taking opiates works for pain – it binds to these opioidergic receptors and suppresses the pain signals.) In the spinal cord, pain signals from the peripheral pathways meet up with the spinal pain signals to send to the brain. Here is where molecules like GABA, opioids made in the body and serotonin control pain transmission.

In chronic pain, serotonin acts to amplify the peripheral pain signals instead of suppress them. Increased serotonin levels and mast cell counts are found in many patients with chronic abdominal pain. About 95% of serotonin in the body is found in the peritoneal cavity, which explains the chronic pain many people feel in this region. Mediators released from colon biopsies in IBS patients were proven to excite the local nerves and activate pain receptors. Serotonin is one of these mediators.

Some antidepressants are known to affect serotonin secretion from mast cells. In particular, tricyclic antidepressants inhibit serotonin release in a dose dependent manner at higher concentrations. Clomipramine was seen to be the most effective, with amitriptyline and doxepin inhibiting release of serotonin and histamine at higher doses. All three were found to affect both uptake and reuptake of serotonin by mast cells and therefore lowering the relative concentration of serotonin in the local environment.

MCAS pain is often difficult to treat with typical pain medications. Antihistamines and cromolyn should be used to manage pain where possible. For bone related pain, bisphosphonates are usually effective. There is some data to suggest hydroxyurea can help manage pain in MCAS patients.

 

References:

Xinning Li, MD; Keith Kenter, MD; Ashley Newman, BS; Stephen O’Brien, MD, MBA. Allergy/ Hypersensitivity Reactions as a Predisposing Factor to Complex Regional Pain Syndrome I in Orthopedic Patients. Orthopedics 2014: Volume 37 · Issue 3: e286-e291

Giovanni Barbara, et al. Mast Cell-Dependent Excitation of Visceral-Nociceptive Sensory Neurons in Irritable Bowel Syndrome. Gastroenterology Volume 132, Issue 1, January 2007, Pages 26–37.

Ferjan, F. Erjavec . Changes in histamine and serotonin secretion from rat peritoneal mast cells caused by antidepressants. Inflammation Research 1996, Volume 45, Issue 3, pp 141-144.

Barbara, V. Stanghellini, R. De Giorgio et al. Activated mast cells in proximity to colonic nerves correlate with abdominal pain in irritable bowel syndrome. Gastroenterology, vol. 126, no. 3, pp. 693–702, 2004.

Barbara, B. Wang, V. Stanghellini et al. Mast cell-dependent excitation of visceral-nociceptive sensory neurons in irritable bowel syndrome. Gastroenterology, vol. 132, no. 1, pp. 26–37, 2007.

Afrin, Lawrence B. Diagnosis, presentation and management of mast cell activation syndrome. 2013. Mast cells.

MCAS: Differing criteria among experts

What criteria you have to meet to be diagnosed with MCAS depends on which doctor you see – even the experts don’t agree.

Molderings, Afrin 2011 Akin, Valent, Metcalfe 2010 Valent, Akin, Castells, Escribano, Metcalfe et al 2012
MCAD (umbrella term including both MCAS and SM) diagnosed if both major criteria, or one major criterion and one minor criterion, are present; following bone marrow biopsy, diagnosis is narrowed down to either SM or MCAS MCAS diagnosed if all criteria are met MCAS diagnosed if all criteria are met

Major Criteria

Multifocal of disseminated dense infiltrates of mast cells in bone marrow biopsies and/or in sections of other extracutaneous organ(s) (GI tract biopsies; CD117-, tryptase- and CD25- stained)
Episodic symptoms consistent with mast cell mediator release affecting ≥2 organ systems evidenced as follows:
  1. Skin: urticaria, angioedema, flushing
  2. Gastrointestinal: nausea, vomiting, diarrhea, abdominal cramping
  3. Cardiovascular: hypotensive syncope or near syncope, tachycardia
  4. Respiratory: wheezing
  5. Naso-ocular: conjunctival injection, pruritus, nasal stuffiness
Typical clinical symptoms
Unique constellation of clinical complaints as a result of a pathologically increased mast cell activity (mast cell mediator release symptom) A decrease in the frequency or severity or resolution of symptoms with antimediator therapy: H1– and H2-histamine receptor inverse agonists, antileukotriene medications (cysteinyl leukotriene receptor blockers or 5-lipoxygenase inhibitor), or mast cell stabilizers (cromolyn sodium) Increase in serum total tryptase by at least 20% above baseline plus 2 ng/ml during or within 4 h after a symptomatic period
  Evidence of an increase in a validated urinary or serum marker of mast cell activation: documentation of an increase of the marker to greater than the patient’s baseline value during a symptomatic period on ≥2 occasions or, if baseline tryptase levels are persistently >15 ng, documentation of an increase of the tryptase level above baseline value on 1 occasion. Total serum tryptase level is recommended as the marker of choice; less specific (also from basophils) are 24-hour urine histamine metabolites or PGD2 or its metabolite 11-β-prostaglandin F2. Response of clinical symptoms to histamine receptor blockers or MC-targeting agents e.g. cromolyn
  Rule out primary and secondary causes of mast cell activation and well-defined clinical idiopathic entities

Minor Criteria

Mast cells in bone marrow or other extracutaneous organ(s) show an abnormal morphology (>25%) in bone marrow smears or in histologies
Mast cells in bone marrow express CD2 and/or CD25
Detection of genetic changes in mast cells from blood, bone marrow or extracutaneous organs for which an impact on the state of activity of affected mast cells in terms of an increased activity has been proved
Evidence of a pathologically increased release of mast cell mediators by determination of the content of:

  1. Tryptase in blood
  2. N-methylhistamine in urine
  3. Heparin in blood
  4. Chromogranin A in blood
  5. Other mast cell specific mediators (leukotrienes, PGD2)

MCAS: GI Symptoms and Liver Abnormalities

MCAS patients suffer a variety of GI ailments, which are largely in common with SM.

Aerophagia, excessive swallowing of air, is very common. It is not entirely obvious why this occurs. In other patient populations, aerophagia is usually due to poor coordination between swallowing and respiration. Severe cases can lead to abdominal distention, aspiration of stomach contents into the lungs and esophageal rupture.

Chest discomfort is common in MCAS. Cardiac issues should be ruled out, but in most people, it is due to esophagitis. Some patients have a previous diagnosis of reflux but it is refractory to all relevant treatments.

Diarrhea and constipation, sometimes alternative, are very common. In one study, 89% of MCAS patients studied had frequent nausea, 100% had abdominal pain of some nature, and 69% had noncardiac chest pain. Partial bowel obstructions are uncommon, but do occur in MCAS. They are thought to be due to focal dysmotility or focal edema.

IBS is a frequent previous diagnosis in MCAS. The GI tract often looks normal by eye and typical H&E staining shows mild inflammation. Staining for mast cells often shows they are increased. Of note, there is not a universal consensus on what is considered “increased mast cells” in GI samples. Generally, above 20 cells per hpf is marked as high by pathologists. Presence of the D816V CKIT mutation is rare in GI biopsies of MCAS patients.

Selective malabsorption of certain nutrients is often seen in MCAS. Iron malabsorption is by far the most common. Copper and B vitamins are often poorly absorbed as well. Protein calorie malabsorption is rare, but leads to weight loss and wasting.

Pancreatic enzyme supplementation can be helpful in treatment of diarrhea, weight loss and malabsorption. The fact that this often works suggests that MCAS driven inflammation or fibrosis causes pancreatic exocrine deficiency, a condition in which the pancreas does not make enough digestive enzymes. Mast cells have a known link to painful chronic pancreatitis. In patients with painful vs painless chronic pancreatitis, mast cell density is 3.5X higher in pancreas biopsy.

About half of MCAS patients have some kind of liver abnormality. Fibrosis (obliterative portal venopathy) is the most common. However, fatty metamorphosis, sinusoidal dilatation, venoocclusive dilatation, nodular regenerative hyperplasia and cirrhosis have also been seen. Sterile (non-infectious) inflammation of the liver and portal trial infiltration by lymphocytes and eosinophils has also been identified in a number of patients. In particular, these patients often have a 2-3X elevation in transaminases and/or alkaline phosphatase, determinants of liver function. Impeded flow of bile from the liver is usually absent. Portal hypertension is unusual but has occurred, causing swelling of the spleen and varices in the esophagus. Rarely, free fluid in the abdomen (ascites) has occurred in MCAS patients.

One study found that 75% of MCAS patients tested had high cholesterol levels. Importantly, 79% of patients had “normal” BMI or were underweight, so the high cholesterol was not correlated to weight. 44% had a twofold or greater elevation of liver enzymes. 36% had increased bilirubin in the blood. 15% had fatty liver; 13% had swelling of the liver; 4% had cysts; 4% had adenomas; 2% had hemangiomas. 14% of patients had pancreatic involvement with elevated lipase or amylase.

 

References:

Kirsten Alfter, Ivar von Ku gelgen, Britta Haenisch, Thomas Frieling, Alexandra Hu lsdonk, Ulrike Haars, Arndt Rolfs, Gerhard Noe, Ulrich W. Kolck, Jurgen Homann and Gerhard J. Molderings. New aspects of liver abnormalities as part of the systemic mast cell activation syndrome. 2009 Liver International 29(2): 181-186.

Afrin, Lawrence B. Presentation, diagnosis and management of mast cell activation syndrome. 2011. Mast Cells.

MCAD: General information for public

Mast Cell Activation Disorders (MCAD): Frequently Asked Questions

What are mast cell activation disorders?

They are a group of conditions  in which the mast cells in the body do not function correctly.  MCAD includes systemic mastocytosis, urticaria pigmentosa and mast cell activation syndrome, among other conditions. Mast cells are responsible for allergic responses. In MCAD, patients can have allergic type reactions to things they are not allergic to. These reactions can be very severe and even life threatening.

What are mast cell reactions?

These are reactions caused by mast cells being improperly activated. These reactions vary from person to person. Symptoms can include, but are not limited to, nausea, vomiting, hives, rashes, itching, flushing (turning red), dizziness, confusion and irritability. Symptoms are caused by the chemicals released by the mast cells.

What causes mast cell reactions?

Triggers vary from person to person. More common triggers include heat, cold, friction (especially on the skin), sunlight, foodstuffs, physical exertion, stress, dyes and fragrances. Triggers can also change over time, with new triggers presenting.

Are mast cell reactions dangerous?

YES. Many MCAD patients will experience uncomfortable reactions throughout their lives. However, every reaction carries the risk of anaphylaxis, a life threatening, severe allergic reaction. Therefore, avoiding reactions as much as possible is very important for mast cell patients. Each patient has an individualized response plan. For many, it involves removal of trigger and administration of medication, such as antihistamines or inhalers.

What is anaphylaxis?

Anaphylaxis is a severe allergic reaction affecting multiple organ systems in the body. These are the kinds of reactions observed in patients with bee sting allergies. Anaphylaxis can be fatal. It is a medical emergency requiring immediate treatment, usually epinephrine (Epipen.) Please receive guidance from treating physician on when to use an Epipen.

How are mast cell anaphylaxis and mast cell reactions different from normal allergies (like food allergies?)

With allergies, your body reacts by a specific method that involves ingesting and recognizing the allergen. In MCAD patients, the mast cells incorrectly think many things are allergens. Since mast cells are so sensitive in these people, ingestion of an allergen is NOT necessary to cause mast cell reactions or anaphylaxis. Smelling a perfume or breathing in very hot, humid air is enough to cause a reaction in many MCAD patients.

What causes MCAD?

Genetic mutations cause different kinds of MCAD. Recent studies have shown that mast cell disease can affect multiple members of the same family.

Why do some MCAD patients have spots?

These spots occur in locations where there are more mast cells than usual in the skin. These are NOT contagious rashes. In addition, MCAD patients who do not have permanent spots often have very sensitive skin, which may cause temporary marks or rashes.

How can I help an MCAD patient be safe?

By not being afraid of their disease. Respect their triggers and help them work around these limitations. Reactions can be painful and very scary, especially for kids. Learn the symptoms associated with reactions and be ready to help with a response plan.

 

Is there more information you feel should be included here?  Let me know in the comments and I can add it in.