Extranodal Rosai-Dorfman Disease : Retroperitoneum
Image Description
Extranodal Rosai-Dorfman disease that presented as large retroperitoneal mass in a young male. The image shows sheets of lesional histiocytes with foamy eosinophilic cytoplasm, and vesicular nuclei with punctate nucleoli. S-100 was strongly positive in the histiocytes. Aggregates of plasma cells are also present.