Extranodal Rosai-Dorfman Disease : Colon

Comments:
Rosai-Dorfman disease involving the colon. The colonic architecture is distorted by a diffuse infiltrate of histiocytes, lymphocytes, and plasma cells in the submucosa. The immunostain shows strong immunoreactivity for S100 in the lesional histiocytes.

Image courtesy of: American Registry of Pathology Press (@ARP_Press); Used with permission.