Dermoscopic Features of Urticaria Pigmentosa in a Nigerian Child: A Case Report

Abstract

Urticaria pigmentosa (UP) is the most common subtype of cutaneous mastocytosis (CM), which is a rare
benign proliferation of mast cells in the skin. Urticaria pigmentosa presents with red-brown macules,
papules, and plaques often located on the trunk, back, and thighs. Lesions of UP, although non-melanocytic
may be confused with melanocytic lesions, such as melanocytic nevus and melanoma. Dermoscopy can
serve as a useful tool for screening melanocytic and non-melanocytic lesions.
We present a two-year-old girl with several hyperpigmented lesions resembling multiple congenital nevi
which turned out to be UP. Dermoscopy showed a dark brown pigment network on a reddish background. A
punch biopsy was done which revealed infiltration of the papillary dermis by inflammatory cells which have
abundant eosinophilic cytoplasm (mast cells). The patient was counselled and placed on loratadine, an
antihistamine. This case describes urticaria pigmentosa in a Nigerian child and its dermoscopic findings, and
this highlights the importance of dermoscopy in distinguishing between urticaria pigmentosa (non –
melanocytic) and melanocytic mimics.
Keywords: Dermoscopy, Urticaria pigmentosa, Cutaneous mastocytosis, Dermatoscopy