Localized Grain-Leather Plaque in Urticaria Pigmentosa – An Unusual Coexistence of Dual Morphology

Urticaria pigmentosa (UP), the most common variant of cutaneous mastocytosis (CM), is characterized by hyperpigmented, brownish macules and patches, with positive Darier's sign. Diffuse cutaneous mastocytosis (DCM), is a rare variant of CM, characterized by diffuse infiltration of the skin by mast cells (MCs), resulting in a typical grain-leather appearance. Blistering is commonly seen in infants with CM but it is not specific for any variant of CM. Herein, we report a case of a 5-month-old male infant who presented with recurrent bullous lesions and hyperpigmented, brownish patches with intervening normal skin suggestive of UP, as well as a single, localized plaque with grain-leather appearance, thereby exhibiting an interesting dual morphology.