Purely cutaneous Rosai--Dorfman disease.

Cutaneous lesions of Rosai-Dorfman disease (RDD) are usually associated with nodal or other extranodal localization. We describe a female patient with RDD clinically limited to the skin. The patient presented with asymptomatic red-brown papules and nodules on the legs, arms, back, and nose. Histologically, the lesions consisted of a proliferation of large histiocytes occasionally showing emperipolesis. Histiocytes were also observed within dilated lymphatic vessels. Immunohistochemical study showed that histiocytes expressed S-100 protein and both macrophage and monocyte markers. All lesions resolved completely with Roentgen therapy. No recurrence has been observed over a 3-year follow-up period.