What is Mastocytosis?


Mastocytosis is a type of mast cell disease in which the body produces too many mast cells.

Mastocytosis also features inappropriate mast cell activation, in which mast cells too easily release their contents, called mediators. These mediators can cause a variety of unpredictable symptoms in both children and adults, including skin rashes, flushing, abdominal pain, bloating, nausea, vomiting, headache, bone pain and skeletal lesions, and anaphylaxis. Triggers can be heat, cold, stress (physical or emotional), perfumes or odors, medications, insect stings, and foods. These symptoms are treated with medications including antihistamines, mast cell stabilizers, and leukotriene inhibitors, while anaphylaxis is a medical emergency often requiring epinephrine. Mastocytosis can affect the skin and internal organs such as the bone marrow, gastrointestinal tract, liver, and spleen. Most patients with mastocytosis have cutaneous (skin) or indolent (benign) systemic forms, but aggressive disease can occur, which may require chemotherapy.

A diagnosis of mastocytosis is confirmed by a bone marrow or skin biopsy. MCAS patients do not fulfill all criteria for mastocytosis but exhibit symptoms, may or may not have increased measurable mast cell mediators (commonly tryptase, histamine or its metabolites) during or shortly after an attack, and often respond to the same medications used to treat the inappropriate mast cell activation in mastocytosis.”

You can read more by going to The Mastocytosis Society website’s Research Page

Mastocytosis has strict diagnostic criteria set by the WHO (World Health Organization).  The patient must meet one major and one minor criterion OR three minor criteria. Diagnosis of Mast Cell Activation Syndrome (MCAS) is based mainly on finding a clinical presentation consistent with chronic mast cell activation, the absence of any other diseases better accounting for all of the findings in the patient, and laboratory evidence of mast cell activation.

People with Systemic Mastocytosis (SM) have a proliferative bone marrow disease. SM is classified as a Myeloproliferative Neoplasm (MPN). The patient’s bone marrow produces too many mast cells, which may be deformed and may not function properly. Those cells may fail to die as soon as normal mast cells die, leading to an increased burden of mast cells.

MCAS patients often have no abnormalities in their bone marrow, with a typical number of regularly shaped mast cells. However, some of these mast cells are inappropriately activated and may be overly sensitive to triggers.

Systemic mastocytosis

  • In systemic mastocytosis, mast cells gather in body tissues, such as the skin, organs and bones. The condition mainly affects adults.
  • Some people with systemic mastocytosis may experience episodes of severe symptoms that last 15-30 minutes. Some patients with systemic mastocytosis have no (or few) symptoms.

During an episode you may have:

  • skin reactions – such as itching and flushing
  • gut symptoms – such as vomiting and diarrhea
  • muscle and joint pain
  • mood changes, headaches, and episodes of fatigue (tiredness)

The episodes are often triggered by:

  • physical exertion
  • certain medications – such as aspirin or antibiotics
  • stress or emotional upset
  • allergic reactions to foods or stings

There are four subtypes of systemic mastocytosis. They are:

  • Indolent mastocytosis – symptoms are usually mild to moderate but can be severe and vary from person to person; indolent mastocytosis accounts for around 90% of adult systemic mastocytosis cases.
  • Aggressive mastocytosis – where mast cells multiply in organs, such as the spleen, liver, and digestive system, to the point where they compromise the functions of those organs; the symptoms are more wide-ranging and severe, although skin lesions are less common.
  • Systemic mastocytosis with associated blood (hematological) non-mast-cell-lineage disease (SM-AHNMD) – this is the diagnosis applied when a hematologic malignancy (such as leukemia) develops together with systemic mastocytosis.
  • Mast cell leukemia (MCL) – a very advanced form of mastocytosis in which there usually are seen large numbers of mast cells circulating in the blood. MCL patients usually live only a few months, if that long, although new treatments being tested show some promise.

To learn more about the diagnosis and treatment of Mastocytosis, go to About Mastocytosis


***This information has been read and approved by Dr. Lawrence Afrin. All content is copyright protected and may not be copied or republished without the approval of the original author. All rights reserved.***


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