Delayed diagnosis of adult-onset mastocytosis.

Urticaria pigmentosa is most frequently observed in children. The associated symptomatology in mastocytosis is vague and not always diagnostic, and Darier's sign is often negative, making the diagnosis challenging. We describe a case of a 61-year-old man with extensive brown papules and macules in different locations of the body that slowly progressed in the last 10 years with a previous anaphylactic reaction after an ant bite. This suggests that urticaria pigmentosa in an adult should be furthered assessed for the possibility of systemic involvement for a correct diagnosis and treatment.