Hirschsprung’s Disease Pathology

Hirschsprung’s disease is a well-established congenital motility disorder, characterized by functional bowel obstruction. The key histological feature of Hirschsprung’s disease is a congenital absence of ganglion cells in both Auerbach and Meissner plexus in the continuous distal bowel beginning at the internal anal sphincter and extending proximally for varying distances. Based on the extent and location of the aganglionic segment, five forms of the disease have been recognized: ultrashort form, conventional short-segment form, conventional long-segment form, total colonic aganglionosis, and extensive aganglionosis. Although there are no definitive criteria in terms of numbers of ganglion cells to distinguish normoganglionosis from the transitional zone, the 50–100 ganglion cells per 1 cm of intestine may provide an indication of the normal range in the neonatal bowel depending on the site or age. The transitional-aganglionic bowel junction on the mesenteric side tends to be more proximal than that on the antimesenteric side. Therefore, intraoperative biopsy in the frozen section diagnosis should be implemented from the mesenteric side. Immunohistochemically, HuC/D reactivity reveals the ganglion cells, while the other neural cells and fibers do not show HuC/D immunoexpression. It is thus useful to identify the numbers and sizes of the ganglion cells.