Cutaneous mastocytosis in the adult: what lies beneath

Mastocytosis is a disorder characterized by clonal mast cell proliferation and accumulation within various organs, most commonly, the skin. Adult-onset mastocytosis is highly suggestive of a systemic involvement and the cases limited to the skin are uncommon. The authors report a 61-year-old male with pruritus associated with hyperpigmented maculopapular skin lesions and a positive Darier's sign. The skin biopsy revealed spindle mast cells infiltrations. The bone marrow study was normal. He started on H1 antihistamines with significant clinical improvement.