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

In 2009, Walker and colleagues published a paper called “Duodenal mastocytosis, eosinophilia and intraepithelial lymphocytosis as possible disease markers in the irritable bowel syndrome and functional dyspepsia.”  The term “mastocytosis” as used here is not equivalent the term “mastocytosis” as in cutaneous mastocytosis or systemic mastocytosis. It is one of several papers to do so and has generated a lot of confusion as a result.

The suffix –osis is commonly used in medical terminology.  It means increase or production of something, but it also connotes that this increase results from a disease process.  Here, the author means not that these patients meet the criteria for systemic mastocytosis, which we know to be a neoplastic disease originating in the bone marrow, but that there are more mast cells than expected in these biopsies.

Excessive production of mast cells in an organ that is not the skin is the defining feature of systemic mastocytosis.  SM patients show some combination of the following characteristics: infiltration of tissue with mast cells clustered together; expression of receptors CD25 and/or CD2 on the mast cells; spindle shaped mast cells; presence of the CKIT D816V mutation; and  baseline tryptase over 20 ng/ml.  When a patient shows too many mast cells without having any of these markers, it is not called mastocytosis.  It is called mast cell hyperplasia.

Consider the following two scenarios:

Let’s imagine that you are a house builder.  For many years, you only build houses when people call your boss and say they need a house.  After your boss gets the call, she calls you to tell you to build a house for these people in the location they have requested.  Sometimes more people need houses than others, so at times you make more, and other times, you make less.  You never build houses unless your boss tells you to and you are able to build them correctly due to having the correct time and resources.  You may think that your boss is telling you to build too many houses sometimes but it is always because she is getting lots of requests from customers to build houses.

In this scenario, mast cells are house builders. They only make new mast cells when they receive appropriate signals from the body.  Sometimes your body makes more mast cells, like to fight an infection or when you have an allergic response.  But the mast cells ALWAYS wait for the correct signal from the body to make more cells.  They do not decide to make too many cells on their own.

Now let’s imagine that after years of being a house builder, you wake up one day with a compulsion to see how fast you can build a house.  Your boss calls you and says she needs one house, so you build that house and then you build four more at the same time.  Instead of building carefully one at a time, you are building five houses at the same time.  This means the houses are not built correctly.  You call your boss to say you are done with the five houses and your boss gets mad.  Where are we going to put these extra four houses?  She decides to move those four houses to another town that doesn’t have too many houses yet.  She tells you not to make too many houses again.

But you just cannot stop making houses.  Making houses is the best!  Who cares if there are little mistakes?  People can still live in them safely.  You wake up every day with a fervent need to build houses.  Your friends and family are concerned about you and stage an intervention.  You will not be moved.  You are building tons of houses at once now.  Your boss is calling you screaming at you to stop making houses because they are defective and she doesn’t have anywhere to put them.  She has been sending them to places that already have too many houses so it is getting really crowded and people are complaining.  You stop answering your boss’s calls.  These people don’t understand the importance of building houses.  No matter what anyone says to you, you will not stop making houses and they cannot make you stop.

In this scenario, the problem isn’t that the boss is telling the builder to make too many houses.  The problem here is that the builder is ignoring all the signals to stop.  This scenario represents systemic mastocytosis.  The mast cells here are making too many mast cells for the wrong reasons and they don’t work right.

I want to be very clear about something – the fact that a person has a lot of mast cells per hpf but doesn’t have markers for SM does NOT mean that these people are not suffering.  Regardless of how the mast cells ended up there in excessive populations, they will cause large scale inflammation and GI symptoms.  Nor am I saying that phenomena like mastocytosis enterocolitis or allergic mastocytic enterocolitis are definitely not mast cell diseases – it is possible that the mast cells in those cases demonstrate markers we have not yet found or that there is an error in the cells that become mast cells.  I am just describing the way these two categories are distinguished from one another at this time.  It is not my intention to disenfranchise anyone.  We are all united in the suckage that is GI symptoms as a result of mast cells.

How do you tell the difference between systemic mastocytosis and mast cell hyperplasia?  That is the purpose of the SM diagnostic criteria.  As I said before, you need to meet one major and one minor criterion, or three minor criteria, from the WHO Systemic mastocytosis criteria.  If you meet some of the criteria, but not enough for SM, that is still evidence of a clonal, proliferative mast cell disease.  This means that it is still evident that too many mast cells are being made despite signals to stop.  The state of meeting some criteria for SM but not enough for an SM diagnosis is called monoclonal mast cell activation syndrome (MMAS). This topic will be covered in detail in a later post in this series.

Many diseases involve mast cells, including various cancers and autoimmune diseases, among others. So why aren’t they considered mast cell diseases like systemic mastocytosis and mast cell activation syndrome? These are not mast cell diseases because in these situations, mast cells are getting signals to make too many mast cells and to cause inflammation.  They are the house builder when the boss is telling them to make more houses than usual, but the boss is doing that because customers need those houses.  Mast cell diseases are the house builder that has a compulsion to build houses even when they aren’t needed and everyone is telling them to stop.

Remember this distinction when you are reviewing papers and pathology reports.  The word mastocytosis is often used when they really mean mast cell hyperplasia.  Mastocytosis in proper usage means too many mast cells because the mast cells are defective.  Mast cell hyperplasia means too many mast cells because the mast cells are receiving inflammatory signals from elsewhere.

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

As I mentioned in the previous post, a 2006 paper counted mast cells in the duodenum (part of the small intestine) and colon of patients with treatment resistant chronic diarrhea and compared these counts to patients with known inflammatory GI diseases and to asymptomatic healthy controls.  This paper posited that cell counts over 20 mast cells/hpf represented a distinct phenomenon called mastocytic enterocolitis.  The author felt that mastocytic enterocolitis was distinct from inflammation caused by other GI diseases, such as Crohn’s colitis, ulcerative colitis and celiac disease.

In this paper, the counts for asymptomatic controls ranged from 3-20 cells/hpf and the counts for known inflammatory GI disease ranged from 2-18 mast cells/hpf.  Patients with chronic diarrhea that resisted treatment demonstrated counts ranging from 13-35 mast cells/hpf.  Mast cells were identified by using an antibody to tryptase.

70% of patients with chronic diarrhea without a known cause had over 20 mast cells/hpf. Cells were counted in 10 hpf and averaged.  Counting in multiple fields and averaging generally gives more representative counts. Based upon this study, it was reasonable to assume that mast cells over 20/hpf was higher than normal. See Table 4 for details.

Table 4: Mast cell counts in duodenum and colon of chronic diarrhea patients (Jakate 2006)
Jakate S, et al. Mastocytic enterocolitis: Increased mucosal mast cells in chronic intractable diarrhea.  Arch Pathol Lab Med 2006; 130 (3): 362-367.
Microscopy method: 400x magnification, mast cells counted in 10 hpf and averaged
Visualization: Tryptase (IHC)
Sample type Study group: Intractible chronic diarrhea Control group A: Inflammatory GI disease that causes chronic diarrhea (ie. Crohn’s colitis, ulcerative colitis, gluten sensitive enteropathy) Control group B: Asymptomatic, healthy controls
Duodenum and colon (counts averaged) Average Range Average Range Average Range
25.7 mast cells/hpf 13-35 mast cells/hpf 12.4 mast cells/hpf 2-18 mast cells/hpf 13.3 mast cells/hpf 3-20 mast cells/hpf

 

In a 2012 paper by Akhavein, the stomach, small intestine and colon of patients with a history of atopic/allergic disease were biopsied.  Mast cells were identified using an antibody to CD117, the CKIT receptor found on the surface of all mast cells. The cells were counted in only 1 hpf.

This paper found that the average mast cell count for biopsies from all organs was 37/hpf.  The author posited that given that these patients had a history of allergic conditions, that a count of over 40/hpf described a phenomenon called allergic mastocytic gastroenteritis that was distinct from the previous described mastocytic enterocolitis.  Cells were scattered and not clustered. There was no control group in this study.  See Table 5 and Table 6 for details.

Table 5: Mast cell count in small intestine of patients with GI pain and dysmotility and a history of allergic disease
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.
Microscopy method: Magnification not explicitly stated, assumed 400x, mast cells counted in 1 hpf
Visualization: CD117 (IHC)
Sample type Study group: atopic/allergic history with abdominal pain and GI dysmotility Control group A:

No control group

 Control group B:

No control group
Small intestine Average Range Average Range Average Range
57 mast cells/hpf 30-90 mast cells/hpf N/A N/A N/A N/A
Diffuse scattered cells, no clusters.

 

Table 6: Mast cell count in colon of patients with GI pain and dysmotility and a history of allergic disease
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.
Microscopy method: Magnification not explicitly stated, assumed 400x, mast cells counted in 1 hpf
Visualization: CD117 (IHC)
Sample type Study group: Diarrhea predominant IBS Control group A:

Healthy controls

 Control group B:

No control group
Colon Average Range Average Range Average Range
37 mast cells/hpf 1-69 mast cells/hpf N/A N/A N/A N/A
Diffuse scattered cells, no clusters.

 

A 2013 paper quantified mast cells in patients with diarrhea predominant irritable bowel syndrome and compared to healthy controls. The patients averaged 26.2 mast cells/hpf in the jejunum, part of the small intestine, while the controls averaged 17.2. Mast cells were identified using an antibody to CD117, the CKIT receptor found on the surface of all mast cells. The cells were likely counted in only 1 hpf as it was not explicitly stated. Distribution of mast cells was not described. See table 7 for details.

 

Table 7: Mast cell count in small intestine of patients diarrhea predominant irritable bowel syndrome
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.
Microscopy method: Magnification not explicitly stated, assumed 400x, number of hpf not explicitly stated, assumed mast cells counted in 1 hpf
Visualization: CD117 (IHC)
Sample type Study group: Diarrhea predominant IBS Control group A:

Healthy controls

 Control group B:

No control group
Jejunum Average Range Average Range Average Range
26.2 ± 11.1 mast cells/hpf N/A 17.2 ± 8.8 mast cells/hpf N/A N/A N/A
Diffuse scattered cells, no clusters. Diffuse scattered cells, no clusters.

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.

 

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.

 

 

 

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

The 2009 Walker paper evaluates the mast cell count in patients with irritable bowel syndrome (both diarrhea and constipation predominant forms) and functional dyspepsia (indigestion, upper abdominal pain). This study recorded the total count of mast cells in five fields.  Additionally, two biopsies from different sections of the duodenum were taken for each patient.  I performed some calculations to convert it to mast cells/hpf to be comparable to other data presented in this series.

Mast cells were identified using an antibody to CD117, the CKIT receptor found on the surface of all mast cells. This paper found that the average mast cell count for each patient (averaged between two biopsy sites) was 33/hpf for functional dyspepsia; 45/hpf average for both types of irritable bowel syndrome; 42.7/hpf for irritable bowel syndrome with predominant diarrhea; 47.7/hpf for irritable bowel syndrome with predominant constipation.  The control group of healthy patients demonstrated an average cell count of 29.4/hpf, with a maximum cell count of 46.5 mast cells/hpf. See Table 9 for details.

Table 9: Mast cell count in stomach of patients with irritable bowel syndrome and functional dyspepsia
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.
Microscopy method: 400x magnification, mast cells counted in 5 hpf and totaled

*Note: I made some calculations to yield information that would be comparable to other research (mast cells/hpf).

 

This paper provided total cell counts in 5 hpf for two biopsies for each patient.  For example, patient A had two biopsies with one having 50 mast cells/hpf and the other having 30 mast cells/hpf. I divided each cell count by 5 to give mast cells/hpf. (50/5 = 10 for biopsy 1; 30/5 = 6 for biopsy 2).  I added these together (10+6 = 16) and divided by 2 to get the average (16/2 = 8 mast cells/hpf).
Visualization: CD117 (IHC)
Sample type Study group: Functional dyspepsia Study group: Irritable bowel syndrome (both diarrhea and constipation groups) Study group: Irritable bowel syndrome, diarrhea Study group: Irritable bowel syndrome, constipation Control group: Healthy controls
Duodenum Average Range Average Range Average Range Average Range Average Range
33 mast cells/hpf 39.2-65.4 mast cells/hpf 45 mast cells/hpf 22.2-74.8 mast cells/hpf 42.7 mast cells/hpf 22.2-65.5 mast cells/hpf 47.7 mast cells/hpf 29.7-74.8 mast cells/hpf 29.4 mast cells/hpf 15.2-46.5 mast cells/hpf
Diffuse scattered cells, no clusters. Diffuse scattered cells, no clusters. Diffuse scattered cells, no clusters. Diffuse scattered cells, no clusters. Diffuse scattered cells, no clusters.

 

A 2012 paper by Zare-Mirzaie evaluated colonic tissue of patients with chronic diarrhea.  Cells were detected by two methods: an antibody to tryptase, and through the use of a simple stain, toluidine blue.  The counts presented in table 10 were found using the antibody to tryptase.  Cells were counted in 10 hpf and averaged.

Table 10: Mast cell count in colon of patients with chronic diarrhea
Zare-Mirzaie A, et al. Analysis of colonic mucosa mast cell count in patients with chronic diarrhea. Saudi J Gastroenterol 2012; 18 (5): 322-326.
Microscopy method: 400x magnification, mast cells counted in 10 hpf and averaged
Visualization: Tryptase, toluidine blue
Sample type Study group: Chronic diarrhea Control group A:

Healthy controls

 Control group B:

No control group
Colon Average Range Average Range Average Range
21.3 ± 4.8 mast cells/hpf 17-24 mast cells/hpf 14.2 ± 3.4  mast cells/hpf 11-17 mast cells/hpf N/A N/A
Diffuse scattered cells, no clusters. Diffuse scattered cells, no clusters.

 

A 2007 paper by Guilarte mentioned mast cell counts in the jejunum (small intestine) of patients with chronic diarrhea.   Cells were detected with an antibody to CD117. The cells were counted in 10 hpf and averaged.  Please note the correct use of the term “mast cell hyperplasia” rather than “mastocytosis.” See Table 11 for details.

Table 11: Mast cell count in colon of patients with diarrhea predominant irritable bowel syndrome
Guilarte M, et al. Diarrhoea-predominant IBS patients show mast cell activation and hyperplasia in the jejunum. Gut 2007; 56: 203-209.

 
Microscopy method: 400x magnification, mast cells counted in 8 hpf and averaged
Visualization: CD117
Sample type Study group: Irritable bowel syndrome, diarrhea Control group A: Healthy controls
Jejunum Average Range Average Range
34 mast cells/hpf 15.3 mast cells/hpf

 

A 2014 paper by Vivinus-Nebot assessed mast cell counts in the colon of patients with persistent GI symptoms in quiescent (inactive) inflammatory bowel diseases.   Cells were detected with an antibody to CD117. The cells were counted in 3 hpf and averaged.  The mast cell counts in this paper were uniformly low.  This implies that mast cells are involved more directly in the inflammatory GI processes, rather than specifically in diarrhea or constipation. See Table 12 for details.

Table 12: Mast cell count in colon of patients with inactive inflammatory bowel conditions
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.
Microscopy method: 400x magnification, mast cells counted in 3 hpf and averaged
Visualization: CD117
Sample type Study group: Irritable bowel syndrome, constipation Study group: Irritable bowel syndrome, diarrhea Study group: Irritable bowel syndrome, mixed Study group: Quiescent Crohn’s disease with irritable bowel syndrome type symptoms
Colon Average Range Average Range Average Range Average Range
12 mast cells/hpf 9-16 mast cells/hpf 12 mast cells/hpf 10-15 mast cells/hpf 12 mast cells/hpf 10-17 mast cells/hpf 12 mast cells/hpf

 

 6-16 mast cells/hpf
Distribution not stated. Distribution not stated. Distribution not stated. Distribution not stated.
Sample type Study group: Quiescent Crohn’s disease Study group: Quiescent ulcerative colitis with irritable bowel syndrome type symptoms Study group: Quiescent ulcerative colitis Study group: Healthy controls
Colon Average Range Average Range Average Range Average Range
12 mast cells/hpf 4-16 mast cells/hpf 12 mast cells/hpf 9-15 mast cells/hpf 10 mast cells/hpf 5-15 mast cells/hpf 6 mast cells/hpf 2-9 mast cells/hpf
Distribution not stated. Distribution not stated. Distribution not stated. Distribution not stated.

 

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.

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.

Get okay

Last week was hard for me.  I’m not entirely sure why it was so hard.  I got bad news, but frankly, I get bad news a lot.  Sometimes it’s harder for me, and I can’t always predict when those times will be.  It’s one of the weird aspects of chronic illness. 

I had a couple days of feeling sorry for myself, which I also need to do occasionally.  Sometimes I need to sleep a lot and complain and wallow in my unfortunateness for a bit.  This invariably leads to getting mad, and that’s just not a place I like to be.  I find that it’s okay to be mad about being sick in an abstract, transient way, but not as a state of being.  I’m not really a person who is angry about being sick, and I think I’m much happier for that fact.
Friday night, I came home from work and was exhausted.  I have been getting really into these MCAS/MMAS papers (which is great – I have learned so much and I’m super excited to share) and I have had a lot of work stuff happening and my brain was fried.  I decided it was time for some self care to head off a mast cell spiral from stress. I put out the (reverse?) bat signal that I wouldn’t be around for the weekend.
I had picked up a bunch of protein drinks and baby food purees to try, so I organized them and tried out a few.  I made some vegetable stock, baked some Red Kori and Carnival squashes and made a sweet Red Kori/ apple soup and a savory Carnival/ caramelized onion soup with a little grated cheese.  I heated up some cranberries and raspberries with sugar and lemon zest and mixed them with milk and yogurt for breakfast drinks.  I did all the dishes while I cooked, tasted everything and sang along to Ingrid Michaelson.  I finished the night with 10 mason jars full of no solids meals for the week.
I woke up Saturday morning to the smell of rain and the chill of autumn blowing into my bedroom.  Me and Story snuggled under my heated blanket and watched American Horror Story for a while.  I cleaned out my closet and cabinets and threw away/ set aside to donate lots of things.  I walked the dogs, did some writing and ate a lot of very buttery, very salty mashed potatoes. 
Today, I woke up really tired and sore, but for the first time in a very long time, I wasn’t nauseous.  I am still very swollen and my GI tract feels like it’s burning, but I am bleeding less.  I’m not enjoying this no solids diet but I have to say that it is helping.  I did some yoga and took Story for a long walk.  I hung out with the family and watched a movie and tried to just relax.
I’m feeling a lot more like myself.  I’d really rather not need biopsies and scopes and surgery, but you get what you get, and it’s easier to just get it over with.  In response to a post last week about how I had gotten bad news, a friend of mine told me to, “Get a plan – and get okay with it.”  It’s great advice and a motto for living with masto if ever I have heard one. 
So I have a plan.  And I’m okay with it.

No solids, clear liquids and NPO

I got phone calls from three of my doctors today.  None of them realized the other two also called.  It was a little funny.
One of the doctors told me they were scheduling an endoscopy and a colonoscopy to get a really thorough look at my GI tract.  They will take biopsies from various parts and stain them to see if my mast cells are generally being terrible people (my money is on this) or if it is something else (I’m looking at you, eosinophils.)  So there’s that.
Another one of my doctors said that in light of the swelling and my persistent bleeding, that I should stop eating solid foods and go on a liquid diet as a stop gap measure to try and stem the inflammation.  I was not expecting to hear this today and I’m feeling pretty sorry for myself, which is not really my style, but is my right.
It got me thinking about the fact that I am pretty used to not eating at all (NPO), or to not eating solids, or to only consuming clear liquids.  This is a side effect of being the vessel for a GI tract that feels it is my mortal enemy.  Before my colostomy surgery, I didn’t eat anything but clear liquids for a few days, while at the same time taking impressive measures to clean the surgical area.  And then I didn’t eat anything for several days after due to post-operative ileus (intestines not moving.) 
So here are my tips for not eating solids or not eating anything but clear liquids.
Figure out which meds will make you hungry.  I take high doses of antihistamines and daily steroids.  These medications increase appetite.  Steroids are actually used in elderly patients to stimulate appetite to keep up their energy.  When I have to take my large doses of antihistamines and steroids, I drink at least 240ml of pureed food (squash soup is a mainstay in my house) or drink at least 500ml of clear liquid about thirty minutes before I take them.  If you are on an NPO (nothing by mouth) order, I recommend starting bolus fluids about thirty minutes before you take your meds.
Set a schedule for liquids and keep it.  Even if you third space like me and oral fluids won’t go to where they’re needed, they will make you feel fuller and suppress appetite.  Keep in mind that suddenly consuming huge amounts of water when you don’t usually will skew your electrolytes, so be sure that you alternate with electrolyte solution.  This is especially true if you have POTS.
Learn how your current dosing affects you without food.  Medication is more available to your body the less solid food you are ingesting.  The cultural touchstone most of us are familiar with is drinking alcohol on any empty stomach.  If you drink on an empty stomach, you get drunker much faster because the alcohol is more available. Medication is the same way.  If you eating thick liquids (pureed food, smoothies), the meds will be more available than if you are eating solid food.  If you are drinking clear liquids, the meds will be more available than if you are eating pureed food.  The difference in both efficacy and side effects can be dramatic.  I recommend having someone with you for the first 48 hours or so until you can predict your reaction to meds. 
Get something for nausea.  Sometimes when you just stop eating, your body misinterprets the problem as there not being enough stomach acid, so it makes extra.  This causes “sour belly” and makes you nauseous.  Additionally, long term hunger will make you nauseous generally, so getting a script for Zofran is helpful. 
It’s okay to add flavor.  When I can only do clear liquids, I make flavor rich, brothy soups and then strain all the solids out.  This way it tastes like chicken soup and not like broth, which really turns my stomach.  Some people chew herbs and spit them out before drinking fluids so that it tastes better.
You are going to be more tired than usual until your body acclimates.  Plan for it. 

So when I am on no solid foods, my day generally looks like this:
630am: Wake up, drink coffee and take thyroid med on empty stomach.
700am: Drink morning milkshake of whatever I feel like milkshaking.  Bemoan the lack of solids in the milkshake.
730am: Take morning meds, including antihistamines and steroids.
800am: 500ml of water.
900am: Cromolyn, 500ml of water.
1000am: Smoothie/soup/whatever.
1100am: 500ml of electrolyte solution.
1200n: Cromolyn, 500ml of water, antihistamines.
1230p: Smoothie/soup/whatever.
200p: 500 ml of electrolyte solution.
300p: Cromolyn, 500ml of water, antihistamines, steroids.
530p: 500ml of water.
600p: Smoothie/soup/whatever.
700p: Cromolyn, 500ml of water.
1000p: Hook up overnight IV fluids (2L.)

1030p: Night time meds. 

This is very generic and gets moved around because I often nap in the afternoon.  I generally drink about 4L of water/electrolyte fluids a day when not eating solids and about 3L a day when I am eating solids. Not eating sucks, but being hungry all the time and not being able to eat sucks worse.  This makes the hunger bearable. 

Gastrointestinal manifestations of SM: Part 2

In SM, the small intestine is sometimes normal when biopsied.  When comparing data across many studies, it is believed that at least 30% SM patients have small bowel structural abnormalities.
In one study, small nodules in the mucosa could be observed in the small intestine in 73% of patients.  It is thought that the small nodules (1 mm) represent focal edema (localized swelling) in superficial mucosa and intestinal villi, while the larger nodules are focal edema in the lamina propria. These nodules do not represent mast cell aggregates.  On endoscopy, biopsy of these lesions showed no aggregates.   
In 23% of patients, lesions show an indistinct jejunal mucosa pattern, probably from excessive secretions.  13% show a malabsorption pattern with flocculation and segmentation; irritability of the muscularis and circular muscle layer is likely responsible for jejunization of ileum in 18% of patients. 
In one study, 57% of patients had small intestinal mucosal thickening, nodularity and/or polypoid lesions.  In a second study, 29% had small bowel abnormalities, including 14% with jejunal or ileal nodules and 14% malabsorption pattern. 
However, a whole host of abnormalities are sometimes seen: thickened jejunal folds with edema; dilated small bowel; blunted villi; partial villous atrophy or edema; complete villous atrophy; infiltration by eosinophils and/or mast cells; spru like mucousal changes responding to gluten free diet; malabsorption with tetany; osteomalacia; vitamin A deficiency; mesenteric thickening or infiltration; bulls eye lesions.
A key aspect of small intestine disease in SM patients is malabsorption.  Previously thought to be rare, multiple studies have now shown that malabsorption is more common in SM and is due to small intestine defects.  Approximately 5-25% of SM have malabsorption, which is generally mild.  One study of SM patients found that 31% had impaired absorptive function.  This was determined by 72-hour fecal fat studies, D-xylose tolerance testing and Schilling test.  Pancreatic function is normal in all SM patients evaluated in these studies. 
An older study found that 23/34 patients studied had elevated fecal fat excretion.  In most, steatorrhea (excess fat in stool) was mild, but it can be severe.  In one study, four patients with steatorrhea all had abnormal findings on biopsy, including villi changes, increased inflammation in the mucosa, increased plasma cells and eosinophils, and sometimes increased mast cells.
Due to the excess excretion of fat in SM patients, they may have malabsorption of fat soluble vitamins such as D or calcium, causing tetany (involuntary muscle contraction) or osteomalacia (softening of the bones.)  Malabsorption of vitamin A can cause night blindness due to rod cone deficiency in retina.
Rarely, celiac disease is reported with SM.  In order to determine which is present, intestinal mucosa must be examined carefully by microscope.  In SM, patients may have patchy lesions with partial villous atrophy.  Enterocytes are normal, which is not seen in celiac.  Sparseness and destruction of crypts in seen in lamina propria, as well as lesions from mast cell infiltration along with neutrophils and eosinophils.  Villous atrophy secondary to crypt atrophy is sometimes seen.  But in SM, there is no crypt hyperplasia.
There have been a few reports of SM patients with selective deficiency of IgA in duodenal fluid only.
For many years, colon involvement was not considered to be an inherent part of SM. More recently, it has been found that up to 20% of SM patients have colon abnormalities.  Diverticulitis occurs in as many as 19% of patients.  Less distension of rectum is necessary to induce pain or urgency in SM patients.  They are also more likely to have overactive rectal contractility and decreased rectal compliance, making complete defecation more difficult.

13% of patients were found to have nodules in the colon mucosa.  Lesions seen by barium examination are thought to be due to edema and not mast cell infiltration, though mast cell infiltration of the colon has been reported.  Mastocytic enterocolitis has been described.  (I’m doing a separate post on this.)

Abnormalities seen include edema with or without granularity, edema with urticarial lesions, purple pigmented lesions.  Diffuse intestinal telangiectasia is sometimes present.  Biopsies of polypoid lesions show extensive infiltration by histiocyte like cells.  In some patients, colon or rectal mucosa showed mixed infiltrates of mast cells and eosinophils, increased mast cells in perivascular spaces, lamina propria, submucosa or muscularis mucosa. 
Diarrhea is a common complaint of SM patients.  There are several possible causes.  Fat absorption can cause diarrhea, but this is unlikely in SM.  It has been shown in these patients that diarrhea can occur with or without fat malabsorption, indicating that the two processes do not stem from a single origin.  Mast cell patients with diarrhea generally do not have malabsorption.  GI transit time in SM diarrhea patients may be normal or even slow, contributing further to the lack of the clarity.
Specific GI regulatory molecules directly causing diarrhea in SM have not been identified, although mediator release can certainly cause this symptom by various pathways.  PGD2 has been suggested repeatedly as a cause.  PGD2 can be 100X normal in SM patients.  In patients with very high prostaglandin levels, use of aspirin decreased diarrhea. 
The treatment for mast cell diarrhea includes the usual suspects, like H1 and H2 antagonists and cromolyn.  Tixocortol was also found to be helpful in decreasing abdominal pain and stool frequency.  Patients who improved with tixocortol also showed improvement on biopsy, decreased fecal fat excretion and increased absorption.

References:
Jensen RT. Gastrointestinal abnormalities and involvement in systemic mastocytosis. Hematol Oncol Clin North Am. 2000;14:579–623.
Bedeir A, et al.  Systemic mastocytosis mimicking inflammatory bowel disease: A case report and discussion of gastrointestinal pathology in systemic mastocytosis.  Am J Surg Pathol.  2006 Nov;30(11): 1478-82.
Lee, Jason K, et al.  Gastrointestinal manifestations of systemic mastocytosis.  World J Gastroenterol. 14(45): 7005-7008.

Gastrointestinal manifestations of SM: Part 1

Gastrointestinal symptoms are among the most common in SM, with up to 80% of patients experiencing them regularly.  When averaging figures from many studies, about 51% of SM patients have abdominal pain, 43% have diarrhea, and 28% have nausea and vomiting.  11% of SM patients have GI bleeding, usually in the upper tract.  Other GI problems common in SM include steatorrhea (excess fat in the stool), malabsorption, swollen liver, swollen spleen, free fluid in the abdomen and portal hypertension.  GI distress in SM can be severe and often mimics Irritable Bowel Disease or Zollinger-Ellison Syndrome.
Abdominal pain in SM generally has two types.  The first is epigastric dyspeptic pain, found in the upper abdomen, and is associated with ulcer disease and oversecretion of stomach acid.  Despite early reports that peptic ulcer disease is rare in SM patients, more recent studies have repeatedly disproven this idea.  On average, about 23% of SM patients have peptic ulcer disease.  Ulcers in SM patients with dyspeptic pain are often found on endoscopy.  In one study, 19% had a duodenal ulcer, while 25% had severe duodenitis.
The other type of GI pain is characterized by lower abdominal cramping.  Generally, one type is more prominent in a patient than the other, and they rarely co-occur with equal intensity.
85-100% of SM patients demonstrate increased histamine production.  Histamine is known to stimulate acid secretion, so SM patients are generally expectly to produce too much acid in the stomach.  However, studies have shown a variety of conflicting results.  Some patients produce too much acid, some too little, and some in the normal range.  For those who overproduce acid, the levels can be extremely high, comparable to levels seen in Zollinger-Ellison Syndrome. 
Occasionally, achlorhydria, the absence of gastric acid, has been found in SM patients.  This is thought to be due to atrophic gastritis (chronic inflammation of the stomach mucosa) that leads to impaired signaling from the local cells; however, this is unproven. 
Multiple studies have attempted to link serum histamine levels with normal basal acid secretion.  In one study, all patients had high serum histamine, but 56% had normal basal acid secretion.  This finding can be attributed to several things, including measured histamine not being fully biologically active; circulating histamine level being less important to acid secretion rate than the level of histamine in the local mucosa.  High histamine has been found in the gastric mucosa of several SM patients with dyspeptic pain. 
Furthermore, the authors elaborated that the histamine levels might not have been high enough to stimulate acid production; that the H2 receptors on acid producing (parietal) cells may have become desensitized to such high histamine levels; or that parietal cells were unable to respond to the histamine signaling, for some other reason.  Of these possible explanations, desensitization is supported by previous research, though not in SM patients.
In a study of 21 patients, 30% of them showed abnormalities on upper GI barium studies.  19% had gastric nodules and 11% had gastritis or peptic disease.  Biopsies of gastric mucosa show increased histamine and increased inflammatory cell infiltration with increased mast cells.  GI symptoms did not correlate with mast cell counts.
Common endoscopic findings in SM patients with dyspeptic pain include: acid hypersecretion; peptic ulcer disease; thickened gastric or duodenal folds; nodular mucosal lesions; occasional altered motility; occasional urticarial lesions; and increased infiltration by inflammatory cells with or without increased mast cells.
Studies have shown that approximately 28% of SM patients have esophageal abnormalities.  These include esophagitis, reflux, varices (abnormally enlarged veins that may bleed) or motor uncoordination.  Difficulty swallowing was common in these patients.  When assessed, these patients showed that the lower esophageal sphincter did not close with enough pressure. 
Esophageal motor function was assessed in 16 patients by manometry.  In 15/16 patients, the esophageal body contractions were normal.  In 62% of these patients, the lower esophageal sphincter function was abnormal.  75% of patients had reflux symptoms.  2/16 did not relax the esophageal sphinter during swallowing.
Esophageal varices have been reported in several SM patients.  The current rate of occurrence is listed as 2.5%, but this is likely an underestimation.
References:
Jensen RT. Gastrointestinal abnormalities and involvement in systemic mastocytosis. Hematol Oncol Clin North Am. 2000;14:579–623.
Bedeir A, et al.  Systemic mastocytosis mimicking inflammatory bowel disease: A case report and discussion of gastrointestinal pathology in systemic mastocytosis.  Am J Surg Pathol.  2006 Nov;30(11): 1478-82.
Lee, Jason K, et al.  Gastrointestinal manifestations of systemic mastocytosis.  World J Gastroenterol. 14(45): 7005-7008.