Congenital Aganglionic Megacolon (Hirschsprung)

Epidemiology and Etiology:

· Migration of neural crest cells arrests at some point before reaching the anus

· Or ganglion cells inappropriate premature death

· An intestinal segment lacks both Meissner submucosal and Auerbach myenteric plexuses

· A variable length of distal gut is not innervated

· M:F = 4:1

· Trisomy 21 (10% of Hirschsprung)

·

Common sites:

· Rectum (always)

· Sigmoid (short-segment disaease involves Rectum and Sigmoid)

· Entire colon (rare) (long-segment disease)

Gross features:

· Intestinal dilation PROXIMAL to the affected segment.

Histologic features:

· Ganglia are absent or nearly so in the affected (contracted) region

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

· At least 8 susceptibility genes have been discovered

· Penetrance of mutations varies

· Familial

· RET

·

Other features:

· Serious neurologic abnormalities (5%)

·

References:

· Kumar V, Fausto N, Abbas A. Robbins & Cotran Pathologic Basis of Disease, Seventh Edition. 7th ed. Saunders; 2004.