Unusual cutaneous histiocytosis expressing an intermediate immunophenotype between Langerhans' cells and dermal macrophages.

Cutaneous histiocytosis was discovered in a 40-year-old man with a slow-growing nodule located on his right arm. Histologic findings showed an epidermotropic infiltrate of histiocytes with folded, irregular nuclei. Immunologically, the cells presented an intermediate phenotype between Langerhans' cells and dermal macrophages. After surgical removal of the lesion, neither a relapse nor visceral involvement was observed during two years of follow-up.