Benign cephalic histiocytosis with diabetes insipidus.

Benign cephalic histiocytosis is a rare skin condition consisting of small tan papules on the face and upper trunk that is believed not to be associated with internal organ involvement. The infiltrating histiocytes are not Langerhans' cells (LCs). We report a 5-year-old girl who presented with diabetes insipidus 1 year after developing multiple small brown asymptomatic skin papules. Histologic examination revealed a non-LC histiocytic proliferation in the dermis without epidermal invasion. She had infiltration of the pituitary stalk on brain imaging. Diabetes insipidus has heretofore been associated with LC histiocytosis and xanthoma disseminatum but not benign cephalic histiocytosis.