Other names: Mastocytosis, Systemic; Systemic Mast Cell Disease
Systemic mastocytosis is a rare disease characterized by uncontrolled proliferation and activation of mast cells in tissues and organs such as the skin, bone marrow, gastrointestinal tract, liver, spleen, or lymph nodes.
In most cases of systemic mastocytosis, there is a mutation in the gene encoding the tyrosine kinase receptor KIT causing a D816V substitution and autoactivation of the receptor.
There are five subtypes of systemic mastocytosis:
- indolent systemic mastocytosis (ISM);
- smoldering systemic mastocytosis (SSM);
- systemic mastocytosis with an associated hematological neoplasm (SM-AHN);
- aggressive systemic mastocytosis (ASM); and
- mast cell leukemia (MCL).
The majority of patients with systemic mastocytosis have the non-advanced forms (ISM and SSM). Advanced systemic mastocytosis (AdvSM) is the term collectively used for the three most aggressive forms of the disease (SM-AHN, ASM, and MCL).
Signs and symptoms of systemic mastocytosis include fatigue, skin flushing, nausea, abdominal pain, bloating, diarrhea, gastroesophageal reflux, nasal congestion, shortness of breath, hypotension, lightheadedness, and headache. Nearly half of individuals with systemic mastocytosis will experience severe allergic reactions.
