Patients with mast cell activationMast cell activation Describes when mast cells release histamine and other mediators into the blood stream in response to an allergen or other trigger. This leads to symptoms like fatigue, rash and, in severe cases, anaphylaxis. syndrome (MCAS) could require annual controls to detect potential progression to systemic mastocytosis (SM), according to a recently published study in ASCP Abstracts.
Individual reports show progression of MCAS to SM, but MCAS is not yet an established risk factor for SM, and progression is not frequent. But the factors that result in MCAS progression to SM in patients are not fully understood.
What is SM?
Systemic mastocytosisMastocytosis Rare disease caused by the buildup of mast cells. Cutaneous mastocytosis primarily affects the skin and is more common in children, while systemic mastocytosis affects internal organs and is more common in adults. (SM) is a rare hematological disease characterized by mast cells that are overactive and accumulate in different parts of the body such as the bone marrow, liver, spleen, gastrointestinal tract and lymph nodes.
Both MCAS and SM share common symptoms such as flushing, diarrhea, abdominal pain and anaphylaxisAnaphylaxis A severe allergic reaction that can turn fatal without treatment. Patients with SM are at a higher risk of developing anaphylaxis. due to pathological mast cell activation. But they are different entities with distinct implications, pathophysiology and treatment.
In an effort to shed light on the subject, the study analyzed data from 47 patients with MCAS following their progression between 2019 and 2021.
During two years, 11% of patients progressed to SM. Five of the 11 patients who progressed to SM had KIT mutations, and six did not. Remarkably, all of the patients with KIT mutations progressed to SM.
The authors observed that baseline tryptaseTryptase A protein enzyme that is primarily produced by mast cells and stored in small pockets within the cells, known as granules. High levels of tryptase are a key indicator of SM. levels correlated with a higher risk of SM progression. The results suggested that patients with MCAS could benefit from annual serum tryptase controls to detect progression to SM as early as possible.
“Identification of prognostic factors, such as specific genetic mutations and baseline serum tryptase levels, may aid in risk stratification and early intervention strategies for individuals with MCAS,” the study said.
SM implies an abnormal mast cellMast cell A type of white blood cell produced in the bone marrow. They help defend against infections and play a key role in allergic reactions. In SM, mast cells become overactive and build up throughout the body. activity with clonal mast cell proliferation. Clonal proliferation is the proliferation of an abnormal number of mast cells from a single progenitor cell, usually with a KIT mutation.
In MCAS, clonal proliferation can be present or not. Patients with SM exhibit symptoms due to mast cell activation and organ infiltration; patients with MCAS present only symptoms of mast cell activation.
MCAS prognosis is mostly benign, and the disease can be managed with antihistaminesAntihistamines Medications that block the effects of histamine, the chemical found in mast cells that is responsible for many of the symptoms of SM, as well as many allergic reactions. and over the counter drugs. SM prognosis depends mostly on the subtype and ranges from indolent SMIndolent SM A subtype of nonadvanced SM caused by the abnormal accumulation of mast cells in the bone marrow and other organs. Indolent SM accounts for around 90% of SM cases. to mast cell leukemiaMast cell leukemia The most severe subtype of SM, caused by the rapid buildup of immature mast cells in the bone marrow and blood. Mast cell leukemia accounts for less than 5% of SM cases and has a poor prognosis. with poor prognosis.
