Rare Presentation of Rosai-Dorfman Disease in Soft Tissue: Diagnostic Findings and Surgical Treatment

Figure 2

Pathologic analysis of the specimen. (a) Grossly, the lesion was well-circumscribed, unencapsulated, and tan-white in appearance. (b) Microscopically, the lesion was characterized by the presence of “light” (histiocyte-rich) and “dark” (lymphocyte-rich) areas. (Hematoxylin & eosin [H&E], 100×). (c) At higher magnification, emperipolesis (arrows) is appreciated, a classic finding in RDD. (H&E, 400×). (d) An S100 immunohistochemical stain highlights the histiocytes in both the light (bottom) and dark (top) areas, further supporting the diagnosis of RDD (S100 immunostain, 200×).

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