Epidemiology of mast cell leukemia: A must!

Abstract

e18537 Background: Mast Cell Leukemia (MCL) is one of the rarest encountered malignancies. It is an aggressive oncologic subtype of systemic mastocytosis (SM) and accounts for <1% of total cases. To make the diagnosis of MCL, in addition to the diagnostic criteria for SM (enlisted in the table), ≥ 20% atypical mast cells should be present in the marrow or ≥ 10% in the peripheral blood. However, an aleukemic form also exists. It can either occur as a de novo mutation or follow mastocytosis. The aim of this epidemiologic study is to aid better understanding of this lesser known aggressive malignancy. Methods: The data was collected from Surveillance, Epidemiology and End Result database Research Plus Data, 17 Registries, Nov 2022 Sub (2000-2020). We extracted Systemic Mastocytosis and Mast Cell Leukemia cases diagnosed after 20 years of age, using the ICD Code 9741/3 (SM) and 9742/3 Mast Cell Leukemia (MCL). The analysis was stratified for MCL based on age, sex, race, and treatment modality used. Results: A total of 795 cases of SM were identified, which were diagnosed between 2000 and 2020. Of which, only 35 cases were attributed to MCL over the last two decades. Of these 35 cases, 60% patients were males, and 40% were females. ~82.85% were Caucasians, ~11.42% were African-Americans, ~2.85% belonged to Asians and Pacific Islanders, and ~2.85% belonged to the Hispanic population. No reported cases were found amongst Alaskan Natives. Further analysis based on survival, gender and races was not done, due to small sample size. Conclusions: MCL accounts for only about 4% of total SM cases. Only 35 cases were identified in the past twenty years, making it one of the rarest encountered malignancies. From the reported data, it was slightly inclined to have male predilection, and Caucasians were the most commonly impacted individuals. Given its extremely low incidence, more research and analysis is warranted to understand this lesser known malignancy. [Table: see text]