Fig. 2
From: Recurrent central nervous system Rosai-Dorfman disease with KRAS mutation: a case report
Histopathology and immunohistochemistry. A Histiocyte proliferation with lymphocyte and plasma cell infiltration in the background (HE staining, 100X). B Histiocytes are rich in cytoplasm, slightly eosinophilic, with round or oval nuclei (HE staining, 400X). C Lymphocytes and plasma cells engulfed within histiocytes. D Histiocytes are positive for S-100 with immunohistochemical staining. E Histiocytes are positive for KP-1 with immunohistochemical staining. F Histiocytes are negative for CD1a with immunohistochemical staining. Histopathological findings (G) and histiocytes positive for S-100 with immunohistochemical staining (H) confirmed the recurrence