Benign isolated histiocytosis mimicking chicken pox in a neonate: report of two cases with ultrastructural study.

Two cases of benign isolated cutaneous histiocytosis X in newborn infants are reported. Clinically, the lesions mimicked chicken pox, and the histologic findings in skin biopsies were indistinguishable from those described in infantile Letterer-Siwe disease. Electron microscopy showed Langerhans' cells with the classical trilaminar, racket-shaped granules. Our cases a well as 10 of the 21 previously reported cases showed spontaneous resolution of the skin lesions. Since this is a benign spontaneous resolving histiocytosis, we recommend that no therapy be given provided that no other signs of systemic involvement are found.