The sudden onset of mastocytosis in the course of venom-induced anaphylactic reaction in a patient with myelodysplastic syndrome.

Mastocytosis is a disease resulting from a proliferation of clonal, abnormal mast cells in tissues and organs, defined as Philadelphia-negative myeloproliferative neoplasm. We present a male patient with clinically, morphologically and immunohistochemically confirmed mastocytosis with preceding myelodysplastic syndrome, occurred after wasp bite in the course of anaphylactic reaction. The propensity to hymenoptera venom-induced anaphylaxis and the presence of an increased population of atypical mast cells in bone marrow found after anaphylactic shock may suggest the possible relationship between hymenoptera venom allergy and anaphylaxis and the development of mastocytosis of unusual course in a predisposed person.