Classification and Pathology of Allied Hirschsprung’s Disease

“Allied disorders of Hirschsprung’s disease (ADHD)” are a disease group characterized by symptoms and signs similar to those of Hirschsprung’s disease (HD), such as delayed passage of meconium and abdominal distention in the newborn period or severe chronic constipation in a young child, despite the presence of enteric ganglion cells. ADHD are classified based on the pathological findings of intestinal ganglia by hematoxylin and eosin (HE) and acetylcholinesterase (AchE) staining of rectal mucosal biopsy, full-thickness biopsy, or intestinal tract specimen obtained at surgery. ADHD with abnormalities of ganglion cells include immaturity of ganglia, isolated hypoganglionosis, and intestinal neuronal dysplasia, diffuse intestinal ganglioneuromatosis, and absence of argyrophil plexus. ADHD showing normal histology of intestinal ganglia include megacystis-microcolon-intestinal hypoperistalsis syndrome, segmental dilatation of the intestine, internal anal sphincter achalasia, and chronic idiopathic intestinal pseudo-obstruction. Rectal mucosal biopsy (RMB) with HE and AchE staining is performed to differentiate ADHD from HD. In the case of persistent symptoms after confirming the presence of ganglion cells and normal AchE activity by RMB, full-thickness biopsies from three locations (at artificial anus, terminal ileum, and sigmoid colon) are required for differential diagnosis.