Patterns of Expression of CD25 and CD30 on Skin Mast Cells in Pediatric Mastocytosis

Abstract

Systemic mastocytosis (SM) is typically associated with CD25-positive mast cells (MCs) in the bone marrow (BM). The expression of CD25 in cutaneous MCs has shown to predict SM in adults. Recently, CD30 has emerged as a novel phenotypical marker of neoplastic MCs. The aim of this study was to investigate the patterns of expression of CD25 and CD30 on skin MCs in children with mastocytosis in the skin (MIS). Skin biopsies from 60 children with MIS were stained for H&E, c-kit, tryptase, CD25 and CD30. Intensity of expression and percentage of immunoreacting cells for the two latter markers were determined following a modified quickscore (Q-score) method. The potential association of clinical and laboratory features with CD25 Q-score and CD30 Q-score values was investigated. Overall, CD25 was expressed by cutaneous MCs in 28% of cases while CD30 in 82%. Positive CD25 expression was significantly more frequent in nodular forms vs. other subtypes of MIS but no correlations were found between CD25 Q-score values and gender, age at onset, extent of MIS, histological pattern, tryptase levels or time to diagnosis. By contrast, a multivariate ordinal regression analysis showed that CD30 Q-score negatively correlated with time elapsed from disease onset to diagnosis. Our results provide the first evidence that most children with MIS show an aberrant immunophenotype in their skin MCs. Based on previous studies in adults, it could be hypothesized that CD25 expression on skin MCs at pediatric ages might be associated with an increased risk for SM.