Generalized eruptive histiocytoma: report of a pediatric case

A one-year-old boy was seen with brownish, flat papules on his face, neck and upper arms. The lesions were symmetric, discrete, slightly raised, firm to the touch, and asymptomatic papular eruptions. Histological and immunohistochemical investigation revealed monomorphous infiltration of S-100 negative, lysozyme negative, and alpha 1-antitrypsin negative, but alpha 1-antichymotrypsin positive and vimentin positive histiocytic cells with small numbers of lymphocytic cells. The histiocytic cells did not show any foamy changes in the cytoplasm. No giant cells were found. The lesions increased in number during the first few years and then spontaneously regressed by the sixth year of age, leaving partial brownish pigmentation.