RESUMO
Mastocytosis is an uncommon, sporadic, heterogenous illness resulting from hyperplasia of mast cells. Diffuse cutaneous mastocytosis is the rarest subtype of mastocytosis affecting children, with bullous mastocytosis being its least common variety. Systemic manifestations like nausea, vomiting, bone pain, diarrhea, and central nervous system abnormalities are less common in children than adults. We report a four-month old male who presented with a two-month history of generalized yellowish to tan macules, papules and plaques with peau d'orange texture, with some blisters and erosions on the back, abdomen and scalp. Darier's sign was positive. Baseline laboratory workup were negative for systemic involvement. CD117 and Giemsa staining were positive for mast cells. Based on the clinical findings and histopathologic results, a diagnosis of bullous mastocytosis was made. Treatment included ketotifen drops, mupirocin cream and cetirizine drops, which resulted in flattening of most lesions and resolution of blisters and erosions.