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Mastocytosis: a mast cell disorder with two forms

Mastocytosis, one of several of mast cell disorders, is caused by a high number of mast cells. Systemic Mastocytosis (SM), the more severe form of the disease, also features elevated levels of tryptase. Cutaneous Mastocytosis (CM) does not, but can develop into SM.1

Patients with SM and CM are at a persistent, elevated risk for potentially fatal allergic reactions.2 Day-to-day, they may also be suffering from symptoms that are intrusive but nondescript, and that can be attributed to a variety of allergic diseases and conditions.3 These symptoms, including flushing, headache, difficulty breathing, runny nose, vomiting, fainting, and even anaphylaxis, can take quite a toll on patients if they persist while the correct diagnosis and treatment plan are identified.1 Many of these patients have coexisting allergies, which also put them at risk for anaphylaxis.4

Up to 30% of patients with mastocytosis also have venom-induced systemic allergic reactions.7

Mastocytosis may affect the skin, liver, spleen, or cardiovascular system, though it is possible for the gastrointestinal tract and nervous system to also be involved.5,6 Following a focused-history, diagnostic test results can support clinicians to quickly and correctly identify all allergic conditions so that patients can start on the most thorough, effective treatment plan possible.

 

Learn about other allergic diseases that may also put patients at risk for anaphylaxis

Test results help identify patients with mastocytosis

Healthcare providers can use tryptase levels to correctly identify patients with SM or CM.4 Baseline tryptase levels are normally stable over time.4 If these levels rise shortly after anaphylaxis and then return to baseline levels with 24 to 48 hours after the event, mastocytosis should be strongly considered.1 A rise of at least 20% above baseline plus 2 μg/l is needed to confirm mast cell activation.5,8

The World Health Organization (WHO) has a consensus on definitions of various forms of mastocytosis and on diagnostic criteria.5

 

Diagnostic Criteria in Systemic Mastocytosis1

 A. Major Criteria
 1. Histological/immunohistochemical alterations: mast cell aggregates containingmore than 15 mast cells in bone marrow sections
 A. Major Criteria
 B. Minor Criteria

1. Cytological alterations: >25% of morphologically abnormal mast cells 

2. Detection of c-kit mutations on codon 816

3. Immunophenotypic alterations: expression of CD25 (±CD2) in mast cells from bone marrow, peripheral blood or other organs

4. Total serum tryptase levels persistently >20ng/mL (not applicable if there is a related blood disorder or evidence of actue mast cell release)

 B. Minor Criteria
 C. Diagnosis of Systemic Mastocytosis

1. At least 1 Major Criterion + 1 Minor Criterion

2. At least 3 Minor Criterion

 C. Diagnosis of Systemic Mastocytosis

Patients with mastocystosis are often at a higher risk for experiencing severe allergic reactions and anaphylaxis.4 Undiagnosed mastocytosis patients may even have a history of up to several idiopathic anaphylactic reactions.9 Identifying patients, at high risk for allergic systemic reactions, arms providers with the information needed to properly educate patients about ways to mitigate these reactions and quell persistent symptoms.4

 

Learn more about the tests used to identify patients with mastocystosis >

Managing the risk for anaphylaxis

Once a patient is known to have mastocytosis, and it is understood that he or she is at an elevated risk for anaphylaxis, a healthcare provider will turn his or her attention to developing a plan for avoiding triggers and allergens that solicit that reaction. If immunotherapy is indicated, it may also inform that treatment plan as well. Triggers and allergens could include animal venoms, temperature extremes, irritation, alcohol, or medications (e.g., aspirin, radiocontrast agents, certain anesthetic agents).3

Ongoing communication, and recurrent testing, are important to keep the patient and provider up-to-date on new or recurring symptoms. It may be possible that new allergies or triggers have developed. In this case, the management plan may need to be modified. Once again, the results of the testing can aid providers with the adjustment and evaluation of the patient’s diagnosis, treatment, and prognosis.3

 

Explore the systems and assays available to your lab >

References
 
  1. Valent P, Akin C, Arock M, 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;157:215-225.

  2. Valent P. Risk Factors and Management of Severe Life-Threatening Anaphylaxis in Patients with Clonal Mast Cell Disorders. Clin Exp Allergy. 2014;44(7):914-920. 

  3. Molderings GJ, Brettner S, Homann J, et al. Mast cell activation disease: a concise practical guide for diagnostic workup and therapeutic options. J Hematol Oncol. 2011;22(4):1-8.

  4. Brockow K, Metcale DD. Mastocytosis. Chem Immunol Allergy. 2010; 95: 110-124.  

  5. Valent P, Akin C, Metcalfe DD. Mastocytosis: 2016 updated WHO classification and novel emerging treatment concepts. Blood. 2017;16;129(11):1420-1427

  6. Akin C, Valent P, Metcalfe DD. Mast cell activation syndrome: Proposed diagnostic criteria. J Allergy Clin Immunol. 2010;126:1099-1104

  7. Pawankar R, Holgate ST, Canonica GW, et al. World Allergy Organization (WAO) White Book on Allergy. 2013.  http://www.worldallergy.org/UserFiles/file/WhiteBook2-2013-v8.pdf. Accessed November 2017. 

  8. Min HK, Moxley G, Neale MC, Schwartz LB. Effect of sex and haplotype on plasma tryptase levels in healthy adults. J Allergy Clin Immunol. 2004;114:48-51. 

  9. Kim JK, Khan DA. Idiopathic Anaphylaxis-A Diagnostic and Therapeutic Dilemma. Curr Treat Options Allergy. 2015;2:183-192.