[Diffuse cutaneous mastocytosis without permanent lesion].

Cutaneous mastocytosis usually includes objective skin signs such as pigmented maculopapulae or skin infiltration. We report an unusual case of cutaneous mastocytosis without systemic involvement in a 9-month old infant. Clinical expression was entirely functional (pruritus, urticaria) with no permanent lesions. There were 22 times more mastocytes found in the skin biopsy than in similar biopsies obtained in healthy control subjects of the same age, which corresponds to the counts found in cutaneous mastocytosis. Diffuse cutaneous mastocytosis with no permanent lesions is an exceptional form of mastocytosis (3 cases reported in the literature). The long-term outcome is unknown. This syndrome should be distinguished from idiopathic anaphylaxis by quantification of the dermal mastocytes.