Muir-Torre syndrome, a rare autosomal dominant inherited disease, is characterized by the synchronous or metachronous occurrence of at least one sebaceous gland neoplasia such as an adenoma or carcinoma, with or without keratoacanthoma, and at least one internal malignancy, mostly colorectal cancer. Visceral malignant neoplasms seem to be less aggressive than their sporadic counterparts. Muir-Torre syndrome has been recognised as a subset of Lynch's syndrome, with similar microsatellite instability and germline mutations in DNA mismatch repair (MMR) genes mainly in MSH2 and/or MLH1. We report the case of a 60-year-old man with a Muir-Torre syndrome, presenting an indolent poorly differentiated duodenal carcinoma. Immunohistochemical analysis revealed the loss of expression of MSH2 and MSH6 proteins in tumor cells. According to medical literature, only 16 cases of Muir-Torre syndrome with small bowel carcinoma have been reported to date.