The phenotypes and other characteristics of patients with advanced systemic mastocytosis (SM) could provide clinicians with improved tools to diagnose and offer prognoses for the disease, according to findings from a recent study conducted in France and published in the journal Haematologica.
Among 81 bone marrow samples that underwent phenotyping, mast cells were detected in 73, the study found. CD2/CD25 expression was reported in 58 of the samples, CD25 alone in 10 samples, neither CD2 nor CD25 in five samples and CD2 alone in no samples.
“Our study provides valuable diagnostic and prognostic information,” the authors reported. “Besides the potential interest from a pathophysiological perspective, the poor prognostic significance of CD2 absence may serve as a cost-effective tool for identifying [patients with] high-risk [advanced SM], especially when next-generation sequencing … is not available,” they added.
“Further studies are required to determine whether this prognostic impact is present in patients treated with avapritinib.”
Read more about SM prognosis
Mastocytosis is a heterogeneous group of hematologic disorders in which the accumulation of neoplastic mast cells is reported in one or more organs of the body, according to the World Health Organization and the International Consensus Classification.
Several variants of mastocytosis have been described, including cutaneous mastocytosis, mast cell sarcoma and systemic mastocytosis. Among individuals with SM, the disease has been further divided into nonadvanced SM and advanced SM forms.
The majority of adult patients with mastocytosis “harbor a D816V mutation in the KIT tyrosine kinase domain (TKD),” the study said. Based on evaluation by flow cytometry or immunohistochemistry, an abnormal phenotype for CD2, CD25 or CD30 expression on bone marrow mast cells is deemed to be distinctive of MC.
All mastocytosis diagnoses of study participants were based on WHO 2016 classification criteria. Data were obtained from medical staff at the French National Referral Center for Mastocytosis (CEREMAST, France). All of the patients in the study were participants in a retrospective, cross-sectional analysis sponsored by the French Association for Research Initiatives on Mast Cells and Mastocytosis.
