Extranodal Rosai-Dorfman Disease : Testis

Comments:
Rosai-Dorfman disease (RDD) of the testis. Higher magnification showing a couple of atrophic seminiferous tubules and a few histiocytes exhibiting emperipolesis. Like other locations, S-100 will stain the lesional histiocytes and highlight emperipolesis.

Image courtesy of: Andres Matoso, MD, Dept. of Pathology, Johns Hopkins Hospital, Baltimore, MD, USA; used with permission.