Findings from a single-center study published in the Journal of Clinical Medicine suggest that patients with systemic mastocytosis with an associated hematologic neoplasm (SM-AHN) have different demographic and biochemical characteristics than individuals with other forms of SM.
SM-AHN occurs when an individual develops both SM and another blood cancer, such as a myeloproliferative neoplasmMyeloproliferative neoplasm SM used to be classified as a type of myeloproliferative neoplasm, a group of rare blood cancers characterized by an overaccumulation of blood cells in the bone marrow., myelodysplastic syndrome, acute myeloid leukemia or chronic lymphocytic leukemia. It is an advanced form of SM with a poorer prognosis that requires treatment focusing on both the SM and associated cancer aspects of the disease.
Learn more: “Subtypes explained: What is SM-AHN?“
The study included seven patients diagnosed with SM-AHN and eight patients diagnosed with other SM subtypes between January 2020 and December 2025. Compared with patients with other subtypes, those with SM-AHN had an older median age (74 years versus 54 years) and lower hemoglobin and platelet levels.
Bone marrow biopsies had substantial variation within the SM-AHN group, with many differences depending on which associated blood cancer was present. This can pose a major diagnostic challenge in some patients with SM-AHN. Because features of the associated neoplasm frequently dominate the bone marrow, it may be harder to find 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. infiltration and diagnose SM.
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Genetic analysis showed further differences between the subtypes. All patients with isolated SM and four of the seven patients with SM-AHN harbored mutations in the KIT gene. However, individuals with SM-AHN were much more likely to carry several mutations in other genes beyond KIT.
The researchers followed participants for a median of 31 months. During this time, four individuals with SM-AHN died, compared with none of the other SM group. The estimated median overall survival in the SM-AHN group was 26 months.
“This analysis provides valuable real-world insights into the diagnostic challenges and complex biology of SM-AHN,” the authors concluded. “Identifying both components of this disease is critical for accurate prognostication and for guiding combined therapeutic strategies to improve patient outcomes.”
The generalizability of these results are limited by the small sample size and single-center design. In addition, all participants in the isolated disease group had 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.. This does not represent the broader population of patients with isolated forms of SM.
