Clinical, epidemiological and laboratory features of insect allergy in cutaneous mastocytosis

Introduction. Mastocytosis is a rare neoplasm characterized by abnormal proliferation and activation of clonal mast cells usually harbouring the KIT D816V mutation. Systemic symptoms of mastocytosis induced by mast cell mediators can occur spontaneously or are provoked by certain stimuli such as hymenoptera insect stings and blood-sucking dipteran insect bites. Today, the epidemiological aspects, features of clinical presentation and laboratory diagnosis associated with insect bites in children with cutaneous mastocytosis are poorly known. Aim. To review the incidence, clinical and laboratory features of insect allergy in children with various clinical forms of cutaneous mastocytosis. Materials and methods. A prospective observational single‐centre study was conducted. It contained information from 310 children who underwent outpatient treatment and observation at the State Budgetary Healthcare Institution – Moscow Center of Dermatovenereology and Cosmetology during the period from March 2022 to October 2024. Results. Reactions to Hymenoptera bites in the group of children with cutaneous mastocytosis developed rarely, in 1.3% of cases. The risk group included children with maculopapular cutaneous mastocytosis with a basal serum tryptase (BST) level above 5.0 μg/L. The proportion of children with systemic manifestations to bites of both stinging and blood-sucking insects and a BST level of more than 8.0 μg/L was 45.5%, which is significantly higher (p < 0.01) than the proportion of children with low BST values (18.1%). Reactions to Diptera (blood-sucking) insect bites were observed in 9.4% of children with all clinical forms of cutaneous mastocytosis. A study of the level of specific IgE to wasp venom showed an insignificant degree of sensitization in all children with systemic reactions to hymenoptera bites. Conclusions. Monitoring the dynamics of tryptase levels in children with cutaneous mastocytosis and timely therapeutic correction of cutaneous manifestations of mastocytosis (vesicles, wheals, itching, flushes) is an important aspect aspect of the prevention of systemic mediator symptoms and anaphylaxis to insect bites. Children with mastocytosis and insect allergy should be treated jointly by a dermatovenerologist and an allergist-immunologist. Particular attention should be paid to patients with monomorphic (“adult”) type of maculopapular cutaneous mastocytosis with tryptase level above 20.0 μg/l, who have risks of developing systemic mastocytosis and anaphylaxis to hymenoptera bites. The results of our study demonstrate the relevance of further study of clinical, epidemiological and laboratory features of insect allergy in a group of children with cutaneous mastocytosis.