A persistent gallstone-an unusual cause of colonic obstruction in sigmoid adenocarcinoma.

An 88-year-old woman presented with acute post-prandial abdominal pain, nausea, and rigors, with biochemical evidence of obstructive jaundice. Computed tomography demonstrated choledocholithiasis with acute cholecystitis and an incidental segment of thickened descending colon. Following endoscopic sphincterotomy with stone extraction and subsequent laparoscopic cholecystectomy, she was discharged home. She re-presented 6 days later with constipation and lower abdominal pain. Repeat imaging revealed large bowel obstruction with marked cecal dilatation due to migration of a gallstone impacted at the site of the previously identified colonic narrowing. Emergency Hartmann's procedure was performed. Histopathology confirmed a moderately differentiated adenocarcinoma of the colon (pT4aN0R0). This case highlights a rare complication of gallstone migration resulting in colonic obstruction, which likely expedited the diagnosis and definitive management of underlying colorectal malignancy.