[size=6]A four-year old boy presents with chronic constipation and numerous failed attempts at medical management. A contrast enema shows a markedly dilated colon. He undergoes a full thickness rectal biopsy with findings consistent with neuronal intestinal dysplasia (NID). The histopathology of NID is best characterized by

 

A hypoplastic ganglion cells.

 

B absence of ganglion cells.

 

C small ganglia within the myenteric plexus.

 

D giant ganglia within the submucosal plexus.

 

E decreased acetylcholinesterase activity in the lamina propria.[/size]

D

D

correct answer

D giant ganglia within the submucosal plexus.

[b]

Neuronal intestinal dysplasia (NID) is a controversial diagnosis based on clinical, manometric and histopathologic findings. The etiology is unknown and its pathogenesis poorly understood. Furthermore, symptoms may not correlate well with the extent of pathologic changes. NID type B, which is the usual form, is considered primarily a malformation of the parasympathetic submucous plexuses. It is a quantitative diagnosis characterized by 15 to 20% giant ganglia in the submucosal layer. Accurate diagnosis requires sufficient submucosal tissue for analysis. There is typically increased acetylcholinesterase staining in the lamina propria or around submucosal vessels. It is difficult to diagnose prior to one year of age since giant ganglia are normally present in the neonatal period. It often coexists with Hirschsprung disease.

 

The much rarer type A is thought to involve the sympathetic innervation.

 

The symptoms of NID are related to chronic constipation and are usually managed conservatively since they may improve with further maturation of the enteric nervous system. However, surgical interventions including proximal diverting enterostomy or segmental resections have been described.[/b]

D

[right]: Intestinal neuronal dysplasia type B is characterized by submucosal plexus hyperplasia with giant ganglia containing increased numbers of ganglion cells (hyperganglionosis). This is the characteristic finding tested here

 

In contrast, the absence of ganglion cells characterizes Hirschsprung disease. Acetylcholinesterase activity may be increased, making option E incorrect.[/right]