Cutaneous Rosai-Dorfman disease--a pathologic review of 2 cases.

Rosai-Dorfman disease, also known as sinus histiocytosis with massive lymphadenopathy, is a rare but distinct clinicopathologic entity characterised histologically by a benign s histiocytic proliferation. Isolated involvement of extranodal sites without concomitant nodal disease is rare. We describe the pathological features of 2 cases of Rosai-Dorfman disease that were clinically confined to the skin. In both male adult Chinese patients, proliferation of histiocytes was accompanied by S-100 protein expression demonstrated immunohistochemically within the histiocytes. The pathology of Rosai-Dorfman disease and its microscopic differential diagnoses are discussed.