Medullary carcinoma of jejunum presenting as perforation peritonitis: A case report.

Small intestinal medullary carcinoma (MC) is a newly recognized subclass of small intestinal carcinomas and is an exceptional entity for this site. A search of the literature for similar cases arising in the small intestine revealed only six previously reported cases. Here we present a case of MC arising in the jejunum of a 65-year-old male. The patient presented to the emergency with features of perforation peritonitis with liver metastasis and no known predisposing factors like inflammatory bowel disease and celiac disease. Studies conducted on this tumor's colonic counterpart have shown microsatellite instability (MSI) and B-type Raf kinase (BRAF) mutations; however, few exceptions are known. Also, this subtype of carcinoma is known to have a better prognosis than its other histological subtypes.