Fibromuscular dysplasia of arteries in Hirschsprung's disease.

Abnormal arteries were demonstrated in the intestines of 8 of 25 children with Hirschsprung's disease. The histologic findings were similar to those seen in fibromuscular dysplasia with proliferation of smooth muscle cells in the thickened adventitia. We propose a new pathological entity, "adventitial fibromuscular dysplasia." The abnormal arteries were located only in the transitional zone, which includes the proximal aganglionic, the oligoganglionic, and the distal normoganglionic segments. These findings are compatible with the suggestion that the craniocaudal migration of ganglion cells might be interrupted by intestinal ischemia in the presence of abnormal arteries in the embryo.