Absent intestinal musculature: anatomic evidence of an embryonic origin of the lesion.

Absent intestinal musculature is a rare entity of uncertain etiology. The diagnosis is confirmed histologically by segmental absence of the intestinal muscularis. The remaining layers of the bowel wall are completely intact, and notably absent are significant inflammation and hemorrhage. The authors report two cases of segmental absence of intestinal musculature presenting as perforations. There was gross or microscopic evidence of diverticula formation at sites of perforation and absent muscle. Based on the anatomic evidence in these specimens and a review of the surgical literature, we propose that the etiology is based on embryologic diverticuli.