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Mastocytosis may be defined as a disorder, caused by an over-abundance of good immune system cells called mast cells and the release of mast cell mediators. Mast cells are responsible for many biological responses in the body (immune, allergic, inflammation, etc.) These cells may also be misshapen or malformed, further contributing to their dysfunction as seen in mastocytosis, mast cell activation syndrome and idiopathic anaphylaxis.

Mastocytosis presents in cutaneous (skin) and systemic (internal) forms. Patients of all ages and genders may present with one or both forms of the disease.

In 2016, the World Health Organization revised the classification of mastocytosis. Until then, mastocytosis was considered as a subgroup of myeloproliferative neoplasms. Due to its unique caracteristics (clinical and pathological features), mastocytosis figures in its own category in the 2016 WHO classification.


Mastocytosis VariantMastocytosis Subvariant
Cutaneous Mastocytosis (CM)

Systemic Mastocytosis (SM)

  • a. Indolent systemic mastocytosis (ISM)
  • b. Smoldering systemic mastocytosis (SSM)
  • c. Systemic mastocytosis with an associated hematological neoplasm (SM-AHN)
  • d. Aggressive systemic mastocytosis (ASM)
  • e. Mast cell leukemia (MCL)


Mast Cell Sarcoma (MCS)




1. Daniel A. Arber, Attilio Orazi, Robert Hasserjian, Jürgen Thiele, Michael J. Borowitz, Michelle M. Le Beau, Clara D. Bloomfield, Mario Cazzola and James W. Vardiman. The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia Blood 2016 127:2391-2405.

2. McNeill,O., Katelaris,C.: Disease Summaries - Mastocytosis: Where are we now? World Allergy Organization July 2011. []

3. Nguyen,N.: Pathology: Mastocytosis (Mast Cell Diseases). The University of Texas, Health Science Center at Houston 2012.

4. Molderings,G., Brettner,S., Homann,J., Afrin,L.: Mast cell activation disease: a concise practical guide for diagnostic workup and therapeutic options. J Hematology & Oncology March 2011. []

5. Valent.P., Horny,H-P., Triggiani.M., Arock,M.: Clinical and Laboratory Parameters of Mast Cell Activation as Basis for the Formulation of Diagnostic Criteria Int Arch Allergy Immunol 2011;156:119-127. May 2011. []

6. Greenberger,P.A: Idiopathic anaphylaxis Immunol Allergy Clin North Am.;27(2):273-93, vii-viii. May 2007. []