Mastocytosis : Sites of Involvement

Comments:
Sites of Involvement: In cutaneous mastocytosis (CM), the mast cell infiltrates are limited to the skin. In systemic mastocytosis (SM), there is involvement of at least one extracutaneous organ, with or without the cutaneous component. The most common extracutaneous site is the bone marrow. Other sites include: spleen, liver, lymph nodes, and gastrointestinal tract. In rare cases, there are sufficient mast cells circulating in the peripheral blood to meet the diagnostic criteria of mast cell leukemia.

Skin lesions in systemic mastocytosis are usually seen with indolent forms. Aggressive variants show skin involvement less frequently.

This photograph shows maculopapular cutaneous mastocytosis (urticaria pigmentosa) in an adult which is an uncommon presentation. Numerous brown macules and papules are present on the trunk. The lesions in adults tend to be more widely disseminated and more heavily pigmented.