The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 5

I have answered the 107 questions I have been asked most in the last four years. No jargon. No terminology. Just answers.

10. How is mast cell disease diagnosed?
• There are several tests you need to definitively determine if you have mast cell disease and what kind you have.
The most well known test for mast cell disease is serum tryptase. This is a blood test. This is the test doctors are most likely to have heard of. Doctors may think that you can’t have mast cell disease if tryptase is normal. This is not true.
• If a patient has a tryptase over 20 ng/mL, the next step is usually a bone marrow biopsy. A tryptase over 20 ng/mL increases the likelihood that a patient has systemic mastocytosis. SM is most commonly confirmed by a bone marrow biopsy.
• You need a special stain in order to see mast cells in any biopsy. Stains that show mast cells include Giemsa Wright stain and toluidine blue. Your doctor should specify these stains.
• Several tests must be run on the bone marrow biopsy to look for clonal mast cell disease. Remember that in clonal diseases, the body makes too many broken cells.
• The shape of the mast cells in the biopsy is very important. If the mast cells are not shaped right, this can be a sign of mast cell disease.
• The number of mast cells grouped together in the body is also important. If 15 or more mast cells are all stuck together, this is called a cluster. When mast cells are clustered together like this, they can punch holes in the tissue and damage it a lot. This prevents the tissue from working right.
• Immunohistochemistry (IHC) is a way to find specific proteins that allow us to know what cells we are looking at in the biopsy. Often, these proteins are on the outside of the cells. Think of these are flags that a cell can wave. IHC can look for the specific flags a cell is waving so that we know for sure which cell is which. For mast cell disease, they want to look for CD117, CD25, and CD2. The CD117 flag is flown normally by all mast cells. CD25 and CD2 are special flags flown by mast cells if you have clonal mast cell disease.
• PCR is a way to look for genetic mutations. They need to look for a mutation in the mast cells in the bone marrow. The mutation is found at a specific place in the CKIT gene. This mutation is found in 80-90% of patients with systemic mastocytosis. It may also be found if patients have monoclonal mast cell activation syndrome.
• If a patient does not have a tryptase over 20 ng/mL, a bone marrow biopsy is often not ordered. There are other tests that can indicate mast cell disease.
• Urine collected over 24 hours can be tested for specific chemicals. In the case of mast cell disease, they are looking for chemicals that can be high if you have mast cell disease. These chemicals have very long, complicated names. I will explain in a later post exactly what they are and what they do. The most common ones are called n-methylhistamine, prostaglandin D2, 9a,11b-prostaglandin F2, and leukotriene E4. Anti-heparin Xa and chromogranin A are sometimes tested. They are much less reliable as indicators of mast cell disease than the others mentioned here.
• If a patient is suspected to have cutaneous mastocytosis, a skin biopsy is needed to confirm. As with bone marrow biopsies, your doctor should specify that they need to use toluidine blue or Giemsa Wright stain to be sure they see the mast cells.
• The skin biopsy should also receive the other tests I described above for bone marrow biopsy: the counting of mast cells and looking at the shape; looking for CD117, CD2, and CD25; and looking for the same mutation with PCR.
11. What kind of doctor diagnoses mast cell disease? Can any doctor order these tests?
Doctors from all different specialties may diagnose and manage mast cell disease. It depends upon the individual provider and where you are located. It could be a dermatologist, allergist, hematologist, pulmonologist, gastroenterologist, or another specialist.
• The serum tryptase is the easier to order and the most well known test. Many labs can run this test.
• The 24 hour urine tests are specialized. Some of them are run in only a few places and samples are usually shipped there. Most often, these samples are run at the Mayo Clinic. Many outpatient labs have no way to run those tests. You will need to speak with your doctor about how to get these tests. It is often easiest if they are run by a hospital lab but again, this depends upon the hospital.
• The PCR genetic test for this specific gene is run in more places than the urine tests but is still not very common. Again, it is often easiest if they are run by a hospital lab.
• A bone marrow biopsy is usually ordered by a hematologist or by another specialist that works commonly with hematologists. They are usually performed by hematology providers. Some testing can usually be performed in house (the counting of the cells and looking at the shape) while others may need to be sent out (the IHC testing).
• A skin biopsy is usually ordered by a dermatologist. Some testing can usually be performed in house (the counting of the cells and looking at the shape) while others may need to be sent out (the IHC testing).
For more detailed reading, please visit these posts:

The Provider Primer Series: Management of mast cell mediator symptoms and release

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

The Provider Primer Series: Cutaneous Mastocytosis/ Mastocytosis in the Skin

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (ISM, SSM, ASM)

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (SM-AHD, MCL, MCS)

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 2

I have answered the 107 questions I have been asked most in the last four years. No jargon. No terminology. Just answers.

3. What causes mast cell disease?

  • The cause of mast cell disease is not yet definitively known.
  • As mentioned yesterday, when the body makes too many copies of a broken cell, those cells are called ‘clonal’ cells. In clonal forms of mast cell disease, the bone marrow makes too many mast cells. Those mast cells also don’t work correctly. Examples of clonal mast cell diseases are systemic mastocytosis and cutaneous mastocytosis.
  • Patients with systemic mastocytosis often have a specific genetic mutation called the CKIT D816V mutation. About 80-90% of systemic mastocytosis patients have this mutation. This mutation is in mast cells and it tells the mast cells to stay alive WAY longer than they should. And mast cells already live for months or years, a very long time for cells to live in the body. So patients with this mutation can end up with way too many broken mast cells.
  • Despite the fact that we know that many patients have this mutation, we do not say that this mutation CAUSES the disease. The reason for this is that sometimes, mast cell patients don’t have the mutation when they get sick but they develop it later. Sometimes, mast cell patients have the mutation and then lose it later. So we are still looking for something that causes the disease.
  • Patients with non-clonal mast cell disease do not have a single major mutation like the CKIT D816V mutation. This makes it harder to diagnose. Researchers have found that many times, patients with MCAS DO have mutations similar to the ones systemic mastocytosis patients do. But the MCAS patients often have different mutations from each other. That’s why it’s not helpful yet for diagnosis.
  • Despite the fact that the mutations described here are not considered to be heritable, there is more and more evidence that mast cell disease can happen to many people in the same family. See the next question for more details.

4. Is mast cell disease heritable?

  • Mast cell disease often affects multiple members of the same family. Importantly, patients often have a different type of mast cell disease than their relatives. This implies that mast cell disease is more of a spectrum rather than several different diseases.
  • A survey found that 74% of mast cell patients interviewed reported at least one first degree relative that had mast cell disease. This same study found that 46% of those patients had mast cell disease that affected more than just their skin. This is called systemic disease.
  • The CKIT D816V mutation is the mutation most strongly associated with clonal mast cell disease. The CKIT D816V mutation is NOT heritable.
  • There are very rare instances of other heritable mutations in families that have mast cell disease. The significance of this is not clear.

5. Can mast cell disease be cured?

  • Generally speaking, there is no cure for mast cell disease.
  • Children who present with cutaneous mastocytosis sometimes grow out of their disease. Their lesions disappear. Their mast cell symptoms affecting the rest of the body may disappear. We do not know why this happens. It has been heavily researched with long term follow up of children with childhood mastocytosis (at least one paper followed them for 20 years).
  • Children with true systemic mastocytosis do not grow out of their disease.
  • There is not yet data on children with MCAS. Anecdotally, they do not seem to grow out of their disease like kids with cutaneous mastocytosis can. Importantly, this is just what it looks like to me. Again, there is no data.
  • People with adult onset mast cell disease have lifelong disease.
  • There is one notable exception to this scenario. There are reports of curing mast cell disease following hematopoietic stem cell transplant/bone marrow transplant.
  • Transplantation is EXTREMELY dangerous. The transplant is MUCH, MUCH more dangerous than mast cell disease. Many people do not survive the protocol necessary to prepare for transplant. Many die from complications, or from a disease they acquired after their transplant.
  • Rarely, people may have malignant forms of mast cell disease, aggressive systemic mastocytosis (ASM) or mast cell leukemia (MCL). A few patients with these diseases have tried transplants after everything else failed. While some did see improvement after transplant, no one has survived more than a few years.
  • Conversely, sometimes people with mast cell disease have these transplants for other reasons, like having another blood cancer or bone marrow disease that requires transplant. In this group of people, some see drastic improvement of their mast cell disease. Some see a full remission of mast cell disease. Some do not get any improvement. These findings are pretty recent so it’s hard to be more specific.

For more detailed reading, please visit these posts:

The Provider Primer Series: Introduction to Mast Cells

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

The Provider Primer Series: Cutaneous Mastocytosis/ Mastocytosis in the Skin

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (ISM, SSM, ASM)

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (SM-AHD, MCL, MCS)

Mast cell disease in families

Heritable mutations in mastocytosis

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 1

I have answered the 107 questions I have been asked most in the last four years. No jargon. No terminology. Just answers.

  1. What are mast cells?
    • Mast cells are white blood cells that live in tissues. It is a little misleading that mast cells are white blood cells because they don’t live in the blood. Mast cells are born in the bone marrow, the squishy tissue inside bones where blood cells are made. From the bone marrow, they are sent to the blood stream. Mast cells use the bloodstream to carry them to their final destination so they do not stay in the blood for very long. Mast cells move out of the blood stream and into tissues throughout the body. Mast cells live for months or years, a long time for cells to live in the human body.
    • Mast cells do many things in the body. They are largely responsible for allergic reactions and anaphylaxis. They have many other jobs, like healing wounds, regulating reproductive activities (menstruation, pregnancy), and fighting infections from viruses, bacteria, fungi, and even intestinal parasites like worms. The original function of mast cells thousands of years ago was probably to fight off intestinal parasites. Mast cells are found in many tissues and are essential for correct functioning of the body.
    • Mast cells have many pouches inside of them called granules. These granules hold chemicals made by the mast cells. These chemicals help the mast cells to do their various jobs. They also help mast cells to communicate with other cells nearby or in other parts of the body. These chemicals can be released into the bloodstream to signal for other immune cells to come to the mast cell that released them.
  2. What is mast cell disease?
    • Mast cell diseases are rare diseases in which your body makes too many mast cells and/or mast cells do not function correctly. In the US, diseases that affect fewer than 200,000 people are called rare diseases.
    • Mast cell diseases are broadly classified into two groups: clonal and non-clonal (also called proliferative and non-proliferative).
    • When the body makes too many copies of a broken cell, those cells are called ‘clonal’ cells. In clonal forms of mast cell disease, the bone marrow makes too many mast cells. Those mast cells also don’t work correctly. They use too much energy on the wrong things. Because these mast cells are often busy making truble, they don’t have as much energy to do their normal necessary functions.
    • Clonal mast cell diseases include all forms of systemic mastocytosis (indolent, smoldering, aggressive, and mast cell leukemia); all forms of cutaneous mastocytosis (urticaria pigmentosa, of which telangiectasia macularis eruptiva perstans is a subtype, diffuse cutaneous mastocytosis); mastocytoma (usually found on the skin but also found elsewhere); mast cell sarcoma; and monoclonal mast cell activation syndrome. Importantly, in clonal mast cell diseases, the problem is not just that too many mast cells are made – those mast cells must also be dysfunctional for the disease to be clonal.
    • In non-clonal mast cell disease, the number of mast cells may be normal, but the cells are broken. Importantly, people with non-clonal mast cell disease may make more mast cells than normal, but not enough to be considered a clonal disease. In these diseases, even if the bone marrow makes the normal amount of mast cells, they still do not work correctly. They use too much energy on the wrong things. Because these mast cells are often working to inflame the body when it is not needed, they don’t have as much energy to do their normal necessary functions.
    • Non-clonal mast cell diseases include all other forms of mast cell disease: mast cell activation syndrome (secondary and idiopathic); familial hypertryptasemia; and mastocytic enterocolitis, which is recognized by some groups as its own disease, and by other groups as part of different mast cell diseases.
    • In these diseases, mast cells do not function properly. In all mast cell diseases, mast cells can get irritated easily. They respond to things in the environment and inside the body that they think are dangerous, even when those things are normal and safe for most people. This response is called mast cell activation.
    • Mast cell activation causes many symptoms. Many of these symptoms are “allergic” in nature. Some are not directly recognizable as “allergic”. Symptoms can affect every bodily system or may be localized to only one or two. It differs from person to person and can change over time within a person. You cannot know which mast cell disease a person has based upon their symptoms.

For more detailed reading, please visit these posts:

The Provider Primer Series: Introduction to Mast Cells

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

The Provider Primer Series: Cutaneous Mastocytosis/ Mastocytosis in the Skin

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (ISM, SSM, ASM)

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (SM-AHD, MCL, MCS)

The Provider Primer Series: Relevance of mast cells in common health scenarios

 

Symptom Cough
Role of mast cells Several mast cell mediators contribute to airway inflammation and subsequent symptoms including cough:

•             Histamine promotes bronchoconstriction, excessive production of mucus, and airway edema.[i]

•             Prostaglandin D2 promotes bronchoconstriction, mucus production, and airway edema.[i]

•             Leukotrienes C4 and D4 and chymase also contribute to mucus production and airway edema.[i]

•             Tryptase promotes overall increased reactivity of the airway.[i]

Chronic airway inflammation, as in asthma, is sometimes associated with increased mast cell population in pulmonary tissues.[i]

Mast cells remain activated in inflamed airways.[i]

Impact of condition on mast cells Mast cell activation can occur as a result of the physical stimuli such as coughing[ii].

Pain can trigger mast cell activation[iii].

Notes regarding condition treatment Dextromethorphan can trigger mast cell degranulation[iv].

Codeine and derivatives can trigger mast cell degranulation[v].

Beta-2 adrenergic agonists, inhaled and oral steroids, and inhaled cromolyn are frequently used in mast cell patients[vi].

Notes regarding mast cell treatment Antihistamines, leukotriene receptor antagonists, and COX inhibitors are routinely taken by mast cell patients and can provide relief.[vii]

Racemic epinephrine can provide relief of pulmonary symptoms.[viii]

Special considerations for mast cell patients Chronic dry, unproductive cough sometimes occurs in mast cell patients.[ix]

Mast cell patients frequently have reactive airways.[ix]

Mast cells can produce and release prostaglandin E2, a mediator that participates in asthmatic inflammation and cough[x].

Prostaglandin E2 can also downregulate or promote mast cell degranulation via binding at prostaglandin E2 receptors on mast cell surface[x].

 

Symptom Sore throat
Role of mast cells Pain can trigger mast cell activation.[iii]
Impact of condition on mast cells Mast cell driven nasal congestion can result in postnasal drip can irritate the throat.[ix]

Mast cell irritation of the throat can present similarly to infection by Streptococcus spp. or other pathogen. Cultures should be taken to properly evaluate for infection.[ix]

Viral, bacterial and fungal infection will activate mast cells through toll like receptors and through perpetuated inflammatory signaling.[xiii]

Notes regarding condition treatment Acetaminophen is recommended for pain relief in mast cell patients.[iv]
Notes regarding mast cell treatment Antihistamines and COX inhibitors are routinely taken by mast cell patients and can provide relief.[vi]
Special considerations for mast cell patients Angioedema of the throat driven by mast cell disease is always a consideration in mast cell patients. If angioedema secondary to mast cell disease impinges upon airway, epinephrine and subsequent anaphylaxis treatments should be undertaken.[vii]

Oral allergy syndrome should be considered.[ix]

 

Symptom Rash
Role of mast cells Acute urticaria is usually driven by mast cell and basophil activation through IgE or non-IgE pathways.[xi]

Mast cell mediators histamine, leukotrienes and platelet activating factor contribute to itching.[xii]

Impact of condition on mast cells Viral, bacterial and fungal infection will activate mast cells via toll like receptors and perpetuated inflammatory signaling.[xiii]

Non-mast cell driven conditions causing skin rashes can irritate mast cells in the skin.[xii]

Pain can trigger mast cell activation.[iii]

Notes regarding condition treatment Some -azole antifungals can induce mast cell degranulation.[xiv]
Notes regarding mast cell treatment Antihistamines and steroids, topical or systemic, and topical cromolyn can provide relief.[xii]
Special considerations for mast cell patients Mediator release by activated mast cells can produce systemic symptoms.[x]

In patients with a history of mast cell disease, mastocytosis in the skin should be considered.

o             Cutaneous mastocytosis accounts for approximately 90% of mastocytosis cases.[xii]

o             Cutaneous mastocytosis lesions demonstrate Darier’s sign, a wheal and flare reaction to touch.[xii]

o             A skin biopsy is necessary to confirm a diagnosis of cutaneous mastocytosis.[xii]

o             Patients with adult onset cutaneous mast cell lesions are usually later found to have systemic mastocytosis.[xii]

 

Symptom Fever
Role of mast cells Mast cells can produce prostaglandin E2.[x]

Mast cells can produce and release several pyrogens, including IL-1α, IL-1β, IL-6, IL-8, TNF, interferon-α, interferon-β, and interferon-γ.[x]

Impact of condition on mast cells Prostaglandin E2 can also downregulate or promote mast cell degranulation via binding at prostaglandin E2 receptors on mast cell surface.[x]

Pain can trigger mast cell activation.[iii]

Viral, bacterial and fungal infection will activate mast cells via toll like receptors and perpetuated inflammatory signaling.[xiii]

Notes regarding condition treatment NSAIDS can trigger mast cell degranulation. Some mast cell patients are unable to take them.[xv]

Acetaminophen is generally recommended for use in mast cell patients.[iv]

Notes regarding mast cell treatment COX inhibitors are routinely taken by mast cell patients and may provide relief.[vi]
Special considerations for mast cell patients

 

Symptom Earache
Role of mast cells Mast cells are involved in the transmission of pain stimuli, including nerve pain.[iii]

Mast cells are involved in sensorineural hearing loss and tinnitus.[ix]

Impact of condition on mast cells Pain can trigger mast cell activation.[iii]

Viral, bacterial and fungal infection will activate mast cells via toll like receptors and perpetuated inflammatory signaling.[xiii]

Notes regarding condition treatment NSAIDS can trigger mast cell degranulation. Some mast cell patients are unable to take them.[xv]

Acetaminophen is generally recommended for use in mast cell patients.[iv]

Steroids (local and systemic) can stabilize mast cells.[vi]

Notes regarding mast cell treatment COX inhibitors are routinely taken by mast cell patients and may provide relief.[vi]

Antihistamines can provide relief for vestibular symptoms.[vi]

Special considerations for mast cell patients Hearing loss, tinnitus and hyperacusis sometimes occur in mast cell patients.[ix]

Sensorineural hearing loss of unknown origin has been documented in mast cell patients.[ix]

Some mast cell patients also have Ehlers Danlos Syndrome which can cause conductive hearing loss.[ix]

Mast cell disease can also cause auditory processing disorder.[ix]

Red ears are a common sign of mast cell activation. Sometimes, only one ear is affected.[ix]

 

Symptom Stomachache
Role of mast cells Mast cells are commonly found in the GI tract.[xvi]

Mast cell activation is involved in a number of GI conditions, including inflammatory bowel disease, ulcerative colitis and food allergies.[xvi]

Mast cell activation can cause chronic diarrhea, pseudoobstruction, obstruction, dysmotility, constipation, nausea, vomiting, and visceral GI pain.[xvi]

Impact of condition on mast cells GI inflammation can recruit mast cells to inflamed tissues.[xvi]

GI inflammation can trigger mast cell mediator release.[xvi]

Pain can trigger mast cell activation.[iii]

Viral, bacterial and fungal infection will activate mast cells via toll like receptors and perpetuated inflammatory signaling.[xiii]

Notes regarding condition treatment
Notes regarding mast cell treatment Histamine H2 blockers and PPIs are commonly taken by mast cell patients and can provide relief.[vi]
Special considerations for mast cell patients Mast cell patients can experience a wide array of severe GI symptoms with or without dense infiltration of GI tract by mast cells.[ix]

 

[i] Cruse G, Bradding P. (2016). Mast cells in airway diseases and interstitial lung disease. European Journal of Pharmacology 778, 125-138.

[ii] Zhang D, et al. (2012). Mast-cell degranulation induced by physical stimuli involves the activation of transient receptor-potential channel TRPV2. Physiol Res, 61(1):113-124.

[iii] Chatterjea D, Martinov T. (2015). Mast cells: versatile gatekeepers of pain. Mol Immunol, 63(1),38-44.

[iv] Dewachter P, et al. (2014). Perioperative management of patients with mastocytosis. Anesthesiology, 120, 753-759.

[v] Brockow K, Bonadonna P. (2012). Drug allergy in mast cell disease. Curr Opin Allergy Clin Immunol, 12, 354-360.

[vi] Molderings GJ, et al. (2016). Pharmacological treatment options for mast cell activation disease. Naunyn-Schmiedeberg’s Arch Pharmol, 389:671.

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

[viii] Walsh P, et al. (2008). Comparison of nebulized epinephrine to albuterol in bronchiolitis. Acad Emerg Med, 15(4):305-313.

[ix] Afrin LB. (2013). Diagnosis, presentation and management of mast cell activation syndrome. Mast cells.

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

[xi] Bernstein JA, et al. (2014). The diagnosis and management of acute and chronic urticaria: 2014 update. J Allergy Clin Immunol, 133(5):1270-1277.

[xii] Hartmann K, et al. (2016). Cutaneous manifestations in patients with mastocytosis: consensus report of the European Competence Network on Mastocytosis; the American Academy of Allergy, Asthma and Immunology; and the European Academy of Allergology and Clinical Immunology. Journal of Allergy and Clinical Immunology, 137(1):35-45.

[xiii] Sandig H, Bulfone-Paul S. (2012). TLR signaling in mast cells: common and unique features. Front Immunol, 3;185.

[xiv] Toyoguchi T, et al. (2000). Histamine release induced by antimicrobial agents and effects of antimicrobial agents on vancomycin-induced histamine release from rat peritoneal mast cells.  Pharm Pharmacol, 52(3), 327-331.

[xv] Grosman N. (2007). Comparison of the influence of NSAIDs with different COX-selectivity on histamine release from mast cells isolated from naïve and sensitized rats. International Immunopharmacology, 7(4), 532-540.

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

 

The Provider Primer Series: Cutaneous mastocytosis/ Mastocytosis in the skin

Mast cell disease: Categories

  • Mast cell disease is the collective term given to several distinct conditions mediated by mast cell dysfunction.  Speaking broadly, mast cell disease has two forms: mastocytosis, a clonal disease marked by excessive proliferation and infiltration of mast cells; and mast cell activation syndrome (MCAS), a disease that presents similarly to mastocytosis but demonstrates no clear indication of excessive proliferation. In addition, monoclonal mast cell activation syndrome (MMAS) can be viewed as straddling the two groupings with markers of clonality but minimum evidence to suggest overproduction of mast cells[i].
  • Mastocytosis has two forms: cutaneous, in which excessive mast cell infiltration is confined to the skin; and systemic, in which an organ that is not skin that is affected by excessive mast cell infiltration. Patients with systemic mastocytosis (SM) often have cutaneous mastocytosis; in this instance, this is called systemic mastocytosis with mastocytosis in the skin[ii].

Mastocytosis in the skin

  • Cutaneous mastocytosis (CM) is a proliferative condition marked by increased mast cell infiltration of the skin.  There are three subvariants of cutaneous mastocytosis: maculopapular cutaneous mastocytosis (MPCM), formerly known as urticarial pigmentosa (UP); diffuse cutaneous mastocytosis (DCM); and solitary mastocytoma of skin[ii].
  • Mast cell density in lesions is usually increased 4-8x above the density in healthy controls. However, some patients have mast cell density comparable to that in healthy controls[ii].
  • All forms of cutaneous mastocytosis can be found in children. Over 78% present by 13 months and some at birth[v]. Childhood onset CM often resolves by adolescence but not always[ii].
  • Most patients with mast cell lesions in childhood have CM rather than SM. Conversely, most patients who develop these macules in adulthood have systemic mastocytosis with mastocytosis in the skin[ii].
  • MPCM (UP) is overwhelmingly the dominant presentation of mastocytosis in the skin. Over 80% of all mastocytosis patients demonstrate the type of cutaneous involvement[ii].
  • In children, MPCM lesions are usually large and have variable morphology which may change over time. In adults, MPCM often occurs as small red/brown macules and may result in few lesions or cover the majority of the body[iii].
  • Telangiectasia macularis eruptive perstans (TMEP) is described as telangiectatic red macules generally found above the midtrunk. While previously thought to be a discrete entity, TMEP is now recognized as a form of MPCM[ii].
  • DCM is almost exclusively found in children with few adult onset cases. It does not present as discrete lesions but rather generalized erythema. Pachydermia may also be present, as well as darkening of the skin[ii].
  • DCM can be associated with formation of severe bullae from a variety of triggers, including rubbing the skin, infections and teething. Due to mast cell release of heparin, it is not unusual for skin wounds to bleed excessively[ii].
  • A mastocytoma is a low grade mast cell tumor most often found on the skin. It is frequently raised and yellow or brown in color. Touching the lesion usually evokes a strong wheal and flare reaction. Sweating may also occur. Blistering may be present[ii].

Diagnosis of mastocytosis in the skin

  • While a biopsy is the definitive diagnostic method, positive Darier’s sign is present in most children and many adults with mastocytosis in the skin. Use of antihistamines can suppress a positive Darier’s sign[ii].
  • Biopsies from lesional skin should be stained for mast cells using toluidine blue or Giemsa-Wright stain; evaluated for CD117, CD25 and CD2 using IHC; and evaluated for activating mutations in the CKIT gene using PCR or sequencing methods[i] .
Diagnostic criteria for cutaneous mastocytosis  (requires one major and one minor criterion)[iii]
Major Minor
Typical mast cell rash, usually maculopapular, or atypical rash with positive Darier’s sign Dense infiltration by tryptase positive mast cells, >15 mast cells/cluster or >20 mast cells/x40 magnification hpf if not clustered
Activating CKIT mutation detected in biopsy from skin lesion

 

Symptoms and treatment of mastocytosis in the skin

  • Common symptoms localized to the skin include flushing, itching, burning, hives and blistering[iv].
  • Mediator release symptoms can affect other organs regardless of whether or not they have systemic mastocytosis. Flushing, nausea, vomiting, diarrhea and low blood pressure have been reported among other symptoms. Wheezing, shortness of breath and rarely cyanosis may be present. Anaphylaxis can also occur[iii].
  • Treatment for cutaneous mastocytosis/mastocytosis in the skin relies upon histamine blockade with H1 inverse agonists and H2 antagonists; cromolyn sodium; leukotriene antagonists; and PUVA treatment in severe cases[v].
  • In treatment resistant cases, systemic glucocorticoids and topical cromolyn may be used.  In some instances, mastocytomas may be excisedi. Anaphylaxis should be treated with epinephrine per current guidelines[v].

[i] Molderings GJ, et al. (2011). Mast cell activation disease: a concise practical guide for diagnostic workup and therapeutic options. J Hematol Oncol, 4(10), 10.1186/1756-8722-4-10

[ii] Hartmann K, et al. (2016). Cutaneous manifestations in patients with mastocytosis: consensus report of the European Competence Network on Mastocytosis; the American Academy of Allergy, Asthma and Immunology; and the European Academy of Allergology and Clinical Immunology. Journal of Allergy and Clinical Immunology, 137(1), 35-45.

[iii] Valent P, et al. (2007). Standards and standardization in mastocytosis: consensus statements on diagnostics, treatment recommendations and response criteria. European Journal of Clinical Investigation, 37, 435-453.

[iv] Carter MC, et al. (2014). Mastocytosis. Immunol Allergy Clin North Am, 34(1), 10.1016/j.iac.2013.09.001

[v] Castells M, et al. (2011). Guidelines for the diagnosis and treatment of cutaneous mastocytosis in children. Am J Clin Dermatol, 12(4), 259-270.

 

Take home points: October 2015

Childhood mastocytosis: Update

  • Cutaneous mastocytosis in children is the most common form of mastocytosis
  • True systemic mastocytosis is very rare in children
  • An NIH study of 105 children found 30-65% improved over time
  • Elevated baseline tryptase level and organ swelling were good indicators of SM
  • Serum tryptase should be measured every 6-12 months
  • Children with swelling of both liver and spleen were positive for CKIT D816V mutation
  • Swelling of liver and spleen together was linked to disease persisting into adulthood
  • Most children with UP with skin and minor GI issues had normal tryptase
  • Diffuse cutaneous mastocytosis patients had a much higher average tryptase but no organ swelling
  • Serum tryptase and IgE were inversely related (high tryptase with low IgE, low tryptase with high IgE)

Chronic mast cell leukemia: a new variant of systemic mastocytosis

  • Mast cell leukemia (MCL) has a significantly shortened lifespan
  • Usually over 20% of nucleated cells in bone marrow are atypical mast cells
  • Mast cells are present in large quantities on the blood
  • Cases where less than 10% of white blood cells in blood are mast cells are called aleukemic variant MCL
  • Cases where over 20% of nucleated cells in bone marrow are mature mast cells are called chronic MCL
  • Chronic MCL patients do not have any C findings (the clinical markers for SM patients associated with very aggressive disease)
  • Chronic MCL patients have stable disease state but can progress to acute MCL at any time
  • Mediator release symptoms are more common in chronic MCL than acute MCL
  • Acute MCL is marked by immature CD25+ mast cells
  • Acute MCL patients do have C findings (the clinical markers for SM patients associated with very aggressive disease)
  • Acute MCL has a very short survival time, usually less than a year

Childhood mastocytosis: Update

One of the more confusing aspects of mastocytosis is that childhood mastocytosis often bears little resemblance to adult-onset mastocytosis and has a very different natural history.  Cutaneous mastocytosis in children is the most common presentation of mastocytosis. True systemic mastocytosis (meeting WHO SM criteria) is quite rare in pediatric cases.

A recent paper describes the features of 105 children assessed at the NIH.  They found that the children in this group either had a stable disease state or improved, with 30-65% getting better over time.  None of the children received cytoreductive therapy.

They found that in this group, children with normal baseline tryptase levels had negative bone marrow biopsies.  A single elevated tryptase level was not determined to correlate well with to a positive bone marrow, rather an elevated baseline tryptase was a good indicator of SM. No children without systemic mastocytosis had organ swelling.

Likewise, all children with systemic mastocytosis had both elevated baseline tryptase and swelling of internal organs.  Bone marrow mast cell burden correlated well with tryptase value. The average tryptase for children with SM in this study was 111.5 ng/ml. Tryptase decreased over time in some SM children.  The researchers recommended evaluation of serum tryptase every 6-12 months.

All children with organ swelling were found to have SM. Children with swelling of both liver and spleen were found to be positive for the D816V CKIT mutation.  Swelling of both of these organs indicates that disease is more likely to persist into adulthood.  Of total 19 children with SM, 16 were positive for the CKIT D816V mutation.

In children with UP, the average tryptase value was 5.9 ng/ml. Twelve children with UP had tryptase values of 11-20, and six had values over 20. Children with UP most often saw significant decreases in tryptase levels over time.   Most UP children with skin and minor GI issues had normal tryptase values.

Children with DCM had much higher average tryptase values, with an average of 67. 85% of DCM children had tryptase over 20 ng/ml when diagnosed.  None of them had swelling of organs.

Of 105 children assessed in this study, 3 had elevated monocytes; 22 had elevated white blood cells; and 12 had elevated platelets.  All of these values returned to normal by the end of the study.  Seven had increased clotting time (PTT). Of those with longer clotting times, four had lupus antibodies and one had Factor VII deficiency. All seven PTT values returned to normal.  Two children with DCM and one with UP had iron deficiency anemia.  One patient had significant elevation of alkaline phosphatase, which resolved.  Researchers noted an inverse correlation between serum tryptase and IgE levels in this group.

Reference:

Carter et al. Assessment of clinical findings, tryptase levels, and bone marrow histopathology in the management of pediatric mastocytosis. J Allergy Clin Immunol 2015.

Progression of mast cell diseases (Part 5)

What is the typical age of onset for children with mastocytosis?

“Mastocytosis [cutaneous, in children]… 55% of cases presenting from birth to 2 years of age, 10% in children younger than 15 years old, and 35% in those over the age of 15. There has, however, been no gender bias noted in the cases of pediatric mastocytosis.” (Frieri 2013)

 

Do symptoms outside of the skin mean my child has systemic, not cutaneous, mastocytosis?

“Systemic symptoms are typically a result of mast-cell mediator release but do not prove systemic mast-cell hyperplasia [overproliferation].” (Frieri 2013)

“Clinical presentation was evaluated in an earlier study conducted by the National Institutes of Health (NIH) in which 83% of the children presented with pruritis, 65% with flushing, 53% with vesicles, 41% with abdominal pain, 18% with bone pain, and least commonly 12% with headache.” (Frieri 2013)

“Systemic mastocytosis in children is extremely rare.” (Frieri 2013)

 

What do studies say about kids growing out of mastocytosis?

“Pediatric mastocytosis is generally a benign disease that is transient in nature, as there is generally a spontaneous regression of the condition by puberty.” (Frieri 2013)

“There was complete regression of disease as defined by cutaneous findings and symptoms (clinical disease severity) in 10 of 15 patients (67%). Three patients had major (20%) and two had partial regression of disease (13%). Repeat marrow examinations on three patients with persistent disease documented systemic mastocytosis based on marrow findings in one patient who had partial regression of disease and was the only patient with initial [] evidence of systemic disease. Of the remaining two patients, one demonstrated partial regression and the other major regression of disease; and neither had evidence of systemic mastocytosis.” (Frieri 2013)

“10 of 15 of patients had complete resolution of cutaneous disease and symptoms at follow-up approximately 20 years later. This resolution of disease, based on cutaneous findings and symptom scores, occurred in the absence of use of topical or systemic steroids, PUVA or cytoreductive agents including imatinib… the natural history of disease is improvement.” (Uzzaman 2009)

“In one [] pediatric report where records and follow-up examinations were available for 25 children with UP, and an average follow-up was approximately 5 years, 76 % improved, 16 % remained unchanged, one had complete disease resolution, and one was worse.” (Uzzaman 2009)

“In a second [] study, 55 children with UP were followed for at least two years after initial examination, during which time 9% had involution of all lesions. In this study, where the average follow-up was 4.1 years, 36% had shown improvement over 6.1 years, and in 55% disease remained unchanged.” (Uzzaman 2009)

“In a third [] study, records of mastocytosis patients [] were available to assess disease outcome over a 1–15 year period. Thirty-five of 62 patients with UP (56%) showed complete disease resolution.” (Uzzaman 2009)

“In a fourth [] study, of 72 cases of UP, 20% cleared disease over an average of 13 years, while 50% improved, 18% were no different, and 10% were worse.” (Uzzaman 2009)

“The age of inception of pediatric-onset cutaneous mastocytosis has been reported to have prognostic implications. In previous studies, skin lesions characterized as hyperpigmented red brown macules or papules typically were reported to appear prior to two years of age. In five such studies with 180, 112, 71, 55 and 17 patients, disease-onset prior to age 2 years was seen in 78, 92, 98, 92, and 82%, respectively. In the majority of patients, these lesions were reported to fade or resolve by late adolescence or early adulthood. Fading or resolution of UP is also reported in some adults (around 20%), although bone marrow disease persisted.” (Uzzaman 2009)

 

How do biopsies of children with mastocytosis differ from adults with mastocytosis?

“In order to analyze the extent of mast-cell hyperplasia, [] bone-marrow biopsies were performed and analyzed. In one study, it was found that in 10 of 17 children with mastocytosis, there were focal areas of mast-cell hyperplasia, which had [] aggregates of mast cells, eosinophils, and early myeloid cells.(Frieri 2013)

“Another study found that the bone-marrow lesions of children had small, [] clusters of mast cells with round and oval nuclei rather than spindle-shaped mast cells, as found in adult bone-marrow lesions.” (Frieri 2013)

“Overall when quantifying mast-cell hyperplasia, there was a higher load of mast cells in children with mastocytosis than in adults with mastocytosis.” (Frieri 2013)

“[T]he difference in presentation between adult and pediatric cases of mastocytosis may result from the difference not only in the mast-cell load but also the distribution of where the mast cells are most likely to be found.” (Frieri 2013)

 

Do increased mast cells in the bone marrow mean my child will not grow out of their disease?

“Five patients had increased mast cells and three patients had spindle shaped mast cells on the initial bone marrow biopsy. One of these patients had complete resolution of clinical and constitutional symptoms at follow-up. Three of the remaining four patients were re-evaluated. One of these was the patient with continued systemic disease, one had persistent DCM and one had continued UP. However, two other patients with continued UP had neither an increase in mast cells nor spindle shaped mast cells noted on original bone marrow examination. Thus, while the presence of increased mast cells and of spindle-shaped mast cells was more often observed in those with persistent disease, the association was not sufficient to predict outcome.” (Uzzaman 2009)

 

Are children with mastocytosis CKIT+?

“Earlier studies by Verzijl found that 25% of pediatric patients with UP had an activating D816V mutation present. Another Longley study found that 36% of pediatric patients had another mutation at codon 816. (This is where the D816V mutation is found.)…One study found that 25% of pediatric patients with the UP form of mastocytosis had a D816V mutation. It was also found that 10 out of 12 patients had another [non-D816V] mutation at the location.” (Frieri 2013)

“A later study by Bodemer in 50 pediatric patients with ages ranging from birth to 16 years found 86% of them had a c-KIT mutation, with 36% being a D816V point mutation, 2 out of 50 cases being a D816Y mutation, and one case being a D816I mutation. There were also 29 of 50 patients with [no mutation] at the 816 codon.” (Frieri 2013)

“44% of the patients were found to have a mutation outside of c-KIT with the mutations lying in exons 8, 9, and 11. There was also a subset of 28% of the patients with a M541L mutation at exon 10. [T]he patients with a M541L mutation had [no mutation] at codon 816. When the blood sample of 13 patients was analyzed, it was found that there was no c-KIT mutation, which suggests that the mutation is somatic rather than germline, meaning that this mutation is not inherited from a patient’s parents.” (Frieri 2013)

 

Do mastocytosis children generally have problems with anesthesia?

Note: always follow appropriate premedication protocols for mast cell patients and work with managing physician.

“Twenty-two patients with pediatric mastocytosis, with a median age of 3.2 years (range 6 months to 20 years) at the time of the procedure, were anesthetized for 29 diagnostic and surgical procedures. All variants of the disease are represented in this series. Most patients had a history of flushing, pruritus, gastroesophageal refux disease (GERD), and abdominal pain; one patient had history of spontaneous anaphylaxis. Routine anesthetic techniques were used, and despite the complexity of the disease, the perioperative courses were uncomplicated and without serious adverse events.” (Frieri 2013)

 

Note: These quotes are all drawn from two papers which extensively referenced previous publications. I ran down the articles referenced, but felt that these two reviews gave excellent summaries, and so I quoted them exclusively.

 

References:

Frieri, Marianne, et al. Pediatric mastocytosis: A review of the literature. Pediatr Allergy Immunol Pulmonol. Dec 1, 2013; 26(4): 175-180.

Uzzaman, Ashraf, et al. Pediatric-onset Mastocytosis: A long term clinical follow-up and correlation with bone marrow histopathology. Pediatr Blood Cancer. Oct 2009; 53 (4): 629-634.

Kettelhut BV., Metcalfe DD. Mastocytosis. J Invest Dermatol 1991; 96:115S–118S.

Lange M., Bogusław Nedoszytko B., Górska A., Żawrocki A., Sobjanek M., Kozłowski D. Mastocytosis in children and adults: clinical disease heterogeneity. Arch Med Sci 2012; 8:533–541.

Bodemer C., Hermine O., Palmérini F., Yang Y., Grandpeix-Guyodo C., Leventhal PS., Hadj-Rabia S., Nasca L., Georgin-Lavialle S., Cohen-Akenine A., Launay JM., Barete S., Feger F., Arock M., Catteau B., Sans B., Stalder JF., Skowron F., Thomas L., Lorette G.Plantin P, Bordigoni P, Lortholary O, de Prost Y, Moussy A, Sobol H, Dubreuil P. Pediatric mastocytosis is a colonal disease associated with D816V and other activating C-KIT mutations. J Invest Dermatol 2010; 130:804–815.

 

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.

 

 

 

Just a horse

This past spring, I started developing a rash on my back.  It was macular and itchy and swelled and turned red when I touched it. 
“It looks like urticaria pigmentosa except it’s not dark,” one doctor told me.  It’s important to note here that my rash pigmentation has been unusual for my entire life.  I have, on several occasions, had rashes misdiagnosed because they were “too pink” or “too faint.”  I don’t know the reason for this, but it happens.  “I’m sure it’s some kind of mast cell issue, your skin is very reactive,” he followed up.
“That is definitely urticaria pigmentosa,” another doctor told me.  He touched the spots and they puffed up and got itchy.  “See, it has a positive Darier’s sign.”  My skin will urticate will very little provocation so I was not convinced.  But I figured I was probably bound to have UP eventually, so I wasn’t very concerned.
“It is probably a mast cell rash, but you should get it biopsied just in case,” a third doctor told me.  By this point, the rash was all over my back and shoulders.  It was itchy, but not all the time.  I scheduled an appointment with a dermatologist. 
I saw the dermatologist on Thursday.  She took one look at it and said, “Oh, that’s not cutaneous mastocytosis.  That’s a harmless fungal rash.  It’s more common in people who are immunosuppressed.  I’ll give you a cream.”
We had a good laugh over the fact that when you have a rare disease, everyone assumes it is the cause of all your symptoms.  She told me a funny story about a patient with several rare diseases who had a “mysterious rash” that the residents couldn’t identify.  It was tinea versicolor, a very common fungal rash.  The residents had assumed it was something exotic and had not considered more mundane options.
Then there was a small fire in the building while I was dressed only in a gown, educating the visiting PCP about systemic mast cell symptoms from skin reactions.  I threw my clothes on and ran outside as the fire department arrived.  Always lively. 
Mast cell disease is hard to manage in part because it can cause so many problems.  But just because it can cause all of them doesn’t mean it does. 
Mast cell patients are zebras, often many times over.  But even zebras mingle with horses once in a while.