Urticaria Pigmentosa – A Case Report with a Review of the Literature

Abstract

Mastocytosis encompasses a rare group of diseases characterized by the accumulation of mast cells, primarily in the skin or internal organs. In the 2016 revised WHO classification, mastocytosis is divided into cutaneous mastocytosis (CM), systemic mastocytosis (CM), and localized mast cell tumor. Cutaneous mastocytosis (CM) includes maculo-papular CM/urticaria pigmentosa (UP), diffuse CM and cutaneous mastocytoma. Urticaria pigmentosa is the most common skin variant. It presents with erythematous brownish macules or papules, often accompanied by pruritus. A case of a 48-year-old woman with disseminated, mildly pruritic, sharply demarcated, livid-brownish macules on the skin of the trunk and extremities is presented. A positive Darier symptom was established. Laboratory tests revealed granulocytosis (73%) and lymphocytosis (19.8%). Serum tryptase and 24-hour urine 5-hydroxyindoleacetic acid were not elevated. The diagnosis of urticaria pigmentosa was confirmed by the histopathological examination revealing perivascular infiltrates of mast cells, mainly in the deep dermis. Screening performed did not detect systemic involvement. Symptomatic treatment with H1 and H2 blockers and topical corticosteroid was carried out. Avoidance of triggers is recommended. The patient's condition has improved. Both a historical review of mastocytosis and a revised classification, as well as the epidemiology, etiology with triggering factors, clinical presentation, laboratory investigations, and management of urticaria pigmentosa are presented.