Solitary congenital indeterminate cell histiocytoma

D. Levisohn, D. Seidel, A. Phelps and W. Burgdorf
Department of Dermatology, University of New Mexico School of Medicine, Albuquerque.

BACKGROUND. Indeterminate cell proliferations are rarely described in the literature. We present a case of a patient who presented at birth with a solitary lesion that spontaneously regressed. OBSERVATIONS. Five cases of indeterminate cell proliferations have been described in the literature. Their clinical patterns display some common features including adult onset, usually with multiple lesions and a relatively benign clinical course. This patient presented at birth with a single lesion and spontaneous regression, as one would expect with congenital self-healing reticulohistiocytosis. Biopsy confirmed a dermal histiocytic nodule that was predominantly CD1 and S100 positive. Unlike patients with congenital self-healing reticulohistiocytosis, however, electron microscopy failed to demonstrate Birbeck granules. CONCLUSION. Indeterminate cell proliferations are a distinct entity. This presentation expands the range of clinical manifestations reported. It also suggests a close relationship between indeterminate cells and Langerhans cells.