Segmental defect of the intestinal musculature of a newborn: evidence of acquired pathogenesis.

Two cases of premature newborns with a segmental defect of the intestinal musculature are presented. The clinical diagnoses were intestinal obstruction and perforation, respectively. Emergency laparotomy was performed. In the first case, this showed a dilated loop of ileum and proximally dilated small bowel. The second case had ileal perforation with marked pneumoperitoneum. Pathological examination showed multifocal partial or complete absence of the muscularis propria, with relative preservation of the remaining components of the bowel wall in both cases. In addition, foci of recent muscular necrosis was noted in case 1, and early replacement fibrosis in case 2. These findings suggest that the muscle defect was secondary to muscle injury rather than a primary absence of muscle. The different theories of pathogenesis are discussed.