The following is a summary of “Standardized indolent systemic mastocytosis evaluations across a healthcare system: implications for screening accuracy,” published in the April 2024 issue of Hematology by McMurray et al.
The timely diagnosis of systemic mastocytosis (SM) poses challenges due to variability in care practices. To address this, researchers implemented a standardized SM screening and diagnosis approach using a novel international registry across the healthcare system. A retrospective analysis was conducted to compare rates of SM, cutaneous mastocytosis (CM), and molecular diagnoses before and two years after implementing standardized care. They evaluated the accuracy of individual and combined SM screening tests, including basal serum tryptase (BST) levels of ≥11.5 and ≥20.0 ng/mL, REMA score of ≥2, presence of monomorphic maculopapular cutaneous mastocytosis (MPCM), and elevated BST based on tryptase genotype.
Following care standardization, tryptase genotyping, and high-sensitivity KIT p.D816V testing substantially increased. SM diagnoses doubled from 47 to 94, and KIT p.D816V molecular diagnoses increased from 24 to 79. Patients diagnosed after standardization had significantly lower mean BST and KIT p.D816V variant allele frequency (VAF) values. The prevalence of hereditary alpha tryptasemia in SM decreased from 13.3% to 6.6% following standardization.
Elevated BST based on genotype and BST ≥11.5 ng/mL showed the highest sensitivities at 84.2% and 88.3%, respectively. Monomorphic MPCM, elevated BST based on tryptase genotype, and the combination of REMA ≥2 with elevated BST based on tryptase genotype had specificities >90%. BST >20.0 ng/mL had low sensitivity and specificity and was unnecessary for diagnosing indolent SM.
Standardizing care increased SM diagnosis rates, particularly in patients with low BST levels. Stratifying BST based on genotype provided the best overall sensitivity and specificity for indolent SM screening tests and improved the specificity of the REMA score.
