Diagnosis: Hirschsprung’s disease
• HD usually presents as delayed passage of meconium and abdominal distention during the neonatal period and as severe constipation and failure to thrive in infancy and childhood.
• 5% to 10% of cases are familial, with association with RET gene mutation.
• Affected segment is narrowed, typically with proximal dilatation of the colon.
• The histopathologic diagnosis of Hirschsprung’s disease is based on the absence of ganglion cells, after consideration of the following: (a) specimen adequacy (submucosal to mucosal ratio of at least 1:1, taken further than 2 cm from anorectal junction, avoiding the physiologic hypoganglionic region) and (b) adequate sampling (multiple levels, immunohistochemical stains for ganglion cells).
• Seromuscular biopsies (which require general anestesia and are associated with greater risk of intestinal perforation) generally yield superiod samples compared to suction biopsies, as both submucosal and myenteric plexus can be examined for ganglion cells.
• Biopsies taken within 2 cm from the pectinate (dentate) line may show few or no ganglion cells (physiologic hypoganglionic segment) as well as prominent nerve fibers, resulting in erroneous diagnostic impression of Hirschsprung’s disease. Presence of squamous or transitional-type epithelium indicates proximity to the anorectal junction and, therefore, precludes the diagnosis of Hirschsprung’s disease.
