Segmental absence of intestinal musculature (SAIM): a case report in an adult.

Segmental absence of intestinal musculature (SAIM) is a rare entity of uncertain aetiology. A case of SAIM in an adult is presented, and three other adult cases of SAIM are reviewed. Our case concerns a middle-aged man who underwent a Whipple's procedure for a suspected neoplasm in the head of the pancreas. At surgery, a redundant segment of proximal jejunum with multiple large diverticula was incidentally noted and resected. On histological examination, the small bowel segment showed focal extreme thinning of the muscularis propria, focally amounting to complete absence. A peritoneal biopsy was also submitted which showed changes consistent with an old thrombosed vessel.