Segmental muscular defects of the intestine: a possible cause of spontaneous perforation of the bowel in adults.

Idiopathic intestinal perforation has been described as spontaneous bowel perforation; only a few cases of the condition have been reported in adults. We conducted a histologic analysis of 7 adult cases of spontaneous intestinal perforation (mean patient age, 63.3 [range, 44-89] years; male-to-female ratio, 1:1.3), which revealed some previously unreported findings. None of the patients had congenital disease. All patients presented with acute abdomen, and intestinal perforations were detected during laparotomy. Perforations, ranging in diameter from a pinpoint size to 3 cm, developed in the colon and small bowel in 4 and 3 cases, respectively. One patient had 2 perforations. Histologic examinations revealed segmental muscularis propria defects around the perforation sites. The extent and degree of the muscular defect varied from case to case; however, all lesions included full-thickness muscular defects. No significant infiltration of inflammatory cells was observed associated with the defects. The mucosa and muscularis mucosa were maintained normally, except in 1 hemorrhagic case. Reparative changes such as granulation were not found; however, short spindle cells or fibroblasts occasionally proliferated around the edges of the disrupted muscularis propria. In 1 case, a muscular defect was also observed in an area far from the perforation site. These findings closely resemble those of neonatal intestine with spontaneous perforation. Etiology of segmental muscular defects in adults is unclear. It may be focal congenital anomaly. In any case, the segmental muscular defects can explain bowel wall weakening, and it can be a major cause of spontaneous perforation of the adult bowel.