Familial adult-onset chronic idiopathic megacolon: diagnostic and surgical challenges—a case report

Chronic idiopathic megacolon is a rare disorder characterized by persistent colonic dilatation without obstruction or secondary causes. It is usually diagnosed in childhood, often linked to Hirschsprung's disease; adult-onset cases are exceedingly rare, especially with familial predisposition. We report a man in his 30s with progressive abdominal distension, prior adolescent colectomy, and family history suggesting genetic susceptibility. After excluding secondary causes, chronic idiopathic megacolon was diagnosed. Conservative management failed, necessitating subtotal colectomy with ileorectal anastomosis, leading to complete symptom resolution. Histopathology confirmed normal ganglion cells. Adult-onset idiopathic megacolon poses diagnostic and therapeutic challenges and may have a genetic basis. Subtotal colectomy is safe and effective in refractory cases.