Cholangiocarcinoma with metachronous urothelial malignancy as a rare manifestation of Lynch syndrome with no gastrointestinal tumour

Lynch syndrome, an autosomal dominant disorder caused by defective DNA mismatch repair genes, is linked to early-onset colorectal, ovarian, gastric, urinary tract and, less commonly, small bowel, biliary and pancreatic cancers. We present a case of a man in his late 50s who presented with obstructive jaundice due to a biliary hilar mass with a history of urothelial malignancy requiring surgical intervention. Family history revealed colon cancer in mother and brother both below the age of 50 years. He underwent curative resection and reconstruction. Histopathology confirmed hilar cholangiocarcinoma. Due to suspicion of Lynch syndrome, microsatellite instability and mismatch repair gene mutation testing were performed, which confirmed loss of nuclear expression of MSH2/MSH6, hence confirming the diagnosis of Lynch syndrome. This enabled the decision to treat with immunotherapy for recurrence and also conduct family screening. In spite of the absence of colonic tumours, Lynch syndrome should be suspected in young patients with multiple tumours, particularly when supported by a relevant family history.