Systemic Reactions After Hymenoptera Sting And Raised Serum Tryptase Strongly Suggest Clonal Mast Cells Disorders

Abstract

BACKGROUND: Anaphylaxis following a hymenoptera sting has been reported in patients with mastocytosis, but few data exist regarding the disease's prevalence in patients with hymenoptera allergy.METHODS: Using bone marrow (BM) histology/cytology, flow cytometry (FC), and detection of KIT mutations, we assessed the prevalence of mastocytosis in patients with both systemic reactions to hymenoptera and increased serum tryptase (sBT).RESULTS: Forty-four out of 379 patients (11.6%) with systemic reactions to sting had increased sBT (>11.4 ng/mL, 95th percentile of normal subjects), and 70.5% of them had a history of sting-induced anaphylaxis. Thirty-four patients underwent a BM analysis. Histology fulfilled major WHO diagnostic criteria in 42.4% of cases. Abnormal mast cells (MCs) were identified by FC and cytology in 78.8% and 61.8% of patients, respectively. A codon 816 KIT mutation was detected in 58.1% of patients. The diagnosis was indolent systemic mastocytosis (ISM) in 61.7% of cases (11.8% with Urticaria Pigmentosa) and Monoclonal MC Activation Syndrome (MMAS) in 26.5%. In particular, 96.4% of patients with anaphylaxis were classified as ISM or MMAS.CONCLUSIONS: Based on the results of the approach utilized in our study, the concomitant presence of systemic reactions (especially anaphylaxis) following hymenoptera sting and raised sBT suggests that a BM examination is indicated in order to diagnose clonal MC disease. BACKGROUND: Anaphylaxis following a hymenoptera sting has been reported in patients with mastocytosis, but few data exist regarding the disease's prevalence in patients with hymenoptera allergy. METHODS: Using bone marrow (BM) histology/cytology, flow cytometry (FC), and detection of KIT mutations, we assessed the prevalence of mastocytosis in patients with both systemic reactions to hymenoptera and increased serum tryptase (sBT). RESULTS: Forty-four out of 379 patients (11.6%) with systemic reactions to sting had increased sBT (>11.4 ng/mL, 95th percentile of normal subjects), and 70.5% of them had a history of sting-induced anaphylaxis. Thirty-four patients underwent a BM analysis. Histology fulfilled major WHO diagnostic criteria in 42.4% of cases. Abnormal mast cells (MCs) were identified by FC and cytology in 78.8% and 61.8% of patients, respectively. A codon 816 KIT mutation was detected in 58.1% of patients. The diagnosis was indolent systemic mastocytosis (ISM) in 61.7% of cases (11.8% with Urticaria Pigmentosa) and Monoclonal MC Activation Syndrome (MMAS) in 26.5%. In particular, 96.4% of patients with anaphylaxis were classified as ISM or MMAS. CONCLUSIONS: Based on the results of the approach utilized in our study, the concomitant presence of systemic reactions (especially anaphylaxis) following hymenoptera sting and raised sBT suggests that a BM examination is indicated in order to diagnose clonal MC disease.