Patients with mast cell activation 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 mastocytosis (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 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 tryptase 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 cell 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 antihistamines and over the counter drugs. SM prognosis depends mostly on the subtype and ranges from indolent SM to mast cell leukemia with poor prognosis.
