Rosai-Dorfman Disease

An 18-year-old man presented with a 3-month history of a rapidly growing, subconjunctival, salmon-colored lesion in the left medial palpebral aperture (A). Excisional biopsy removed a well-defined, gelatinous mass (B). Histopathology revealed lymphocytes, plasma cells and histiocytes with large, round nuclei, voluminous cytoplasm, and occasional emperipolesis (engulfment of lymphocytes) (C, arrow). Histiocytes demonstrated positive S100 immunostaining (D), confirming the diagnosis of extra-nodal Rosai-Dorfman disease. Rosai-Dorfman disease is a rare, non-Langerhans histiocytosis of unknown etiology predominantly affecting children and young adults. Unifocal disease can be treated surgically, although immunosuppressive agents are used for more extensive disease. The clinical course is typically benign (Magnified version of Figure A-D is available online at www.aaojournal.org).