ABSTRACT
Introduction: Mastocytosis encompasses a heterogeneous group of diseases characterized by an accumulation of clonal mast cells (MC) in the skin and/or internal organs, and symptoms of MC activation. This MC activation can be elucidated by several factors, including infections or vaccination. Objective(s): We present our experience with COVID infection and vaccination in a series of 133 patients with pediatric mastocytosis. Method(s): Between January 1998 and December 2022, 133 pediatric patients have been referred to our hospital owing to clinically suspected MC disorder, mainly with mastocytosis in the skin. The final diagnoses of mastocytosis were established by the presence of typical skin lesions together with an increase of MC numbers in a biopsy from lesional skin or activating KIT mutations in lesional skin tissue. Serum baseline tryptase and total immunoglobulin E levels were measured, and patients underwent a comprehensive allergy workup to confirm atopic status and history of anaphylaxis. Regarding vaccination, REMA's (Spanish Network on Mastocytosis) protocol was followed. Result(s): 13 patients with COVID infection were identified, of which 25 (56,8%) were female and 0% had symptoms of MC activation. All of them had an asymptomatic or mild course of COVID infection. None of the patients experimented MC activation symptoms during viral illness. Regarding COVID vaccination, all patients received premedication with antihistamine 60 minutes prior vaccination. No one experimented immediate reactions and only one patient (0,75%) referred worsening of MC activation symptoms (baseline pruritus, urtication and brain fog) only after the first doses, recovering without changes in his treatment (oral cromoglycate and antihistamine) in two months. Discussion(s): Although MC have been implicated in the pathogenesis of cytokine storm in COVID19, there is no clinical evidence of SARSCoV- 2-induced MC activation, perhaps related to the fact that bone marrow MC lack angiotensin-converting enzyme 2 receptors.