Extranodal histiocytic sarcoma mimicking colorectal lymphoma: Case report and review of literature.

Histiocytic sarcoma is a rare malignant neoplasm that demonstrates mature histiocytic traits as characterized by immunohistochemistry. We report a case of extranodal histiocytic sarcoma (ENHS) of colon in a 56-year-old man presenting with gastrointestinal symptoms. Radiological findings were indicative of lymphoma or diffuse metastatic disease in colon. Histopathology of colectomy specimen was suggestive of ENHS, and immunohistochemical studies confirmed the uncommon diagnosis. The patient refused further therapy and succumbed to systemic complications of metastatic disease within a month of diagnosis. There have only been seven previous reports in world literature of ENHS involving large intestine.