The histopathology of congenital pouch colon associated with anorectal agenesis.

The colonic pouch excised during surgery in 17 patients with congenital pouch colon associated with anorectal agenesis (CPC) was subjected to detailed histological examination after staining with hematoxylin and eosin. The patients included 11 newborns, 3 infants, and 3 older children. The most frequently observed abnormalities were acute and chronic inflammation of the mucosa and submucosa, focal or generalized thinning of muscle layers, especially of the outer muscle coat, disorganized muscle layers, a decreased number of mature ganglion cells, and neuronal hyperplasia and hypertrophy in nerve plexuses. Ectopic heteroplastic tissues were identified in 2 patients. These findings suggest that the colonic pouch in CPC represents abnormally developed colonic tissue and points to the similarity with segmental dilatation of the colon. The neuromuscular abnormalities explain the physiological characteristics of the colonic pouch, namely weak peristalsis as well as the propensity to undergo marked dilatation even after tubularization.