Mastocytosis, also known as mast cell disease, is an uncommon disorder caused by the accumulation of a normally rare white blood cell type called mastocytes. Normal mastocytes are involved in fighting certain infections but are most well known as the primary cells that drive allergic responses. Mastocytosis occurs when abnormal amounts of mastocytes accumulate throughout the body in places such as the skin, bone marrow, airways, and internal organs (liver, spleen, gastrointestinal tract, and lymph nodes). 

Mastocytosis disorders can be classified along a spectrum from indolent systemic mastocytosis to mast cell leukemia. Most new diagnoses are made while a patient is in the indolent stage, or the stage with the best prognostic category. While mastocytosis tends to be persistent in most adult patients, many can remain in the indolent stage for much of their lives. Progression to a more advanced category only occurs in a minority of patients.

Mastocytosis can cause problems because factors produced by the abnormal mastocytes can scar and damage the host organs. Because of this, patients receiving treatment for this disease will see a wide range of physicians in addition to MPN specialists, such as allergists, gastroenterologists, neurologists, and psychiatrists in order to manage symptoms they may be experiencing.

Richard T. Silver MD Myeloproliferative Neoplasms Center 525 East 70th St., Starr Pavillion, 3rd Floor New York, NY 10021