A 35-year-old patient with known FAP undergoes surveillance colonoscopy showing thousands of colonic polyps plus a desmoid tumour in the mesentery. The APC mutation has been localised to codon 1328 (between codons 1310–1444, genotype 3B). What surgical option is MOST appropriate for the colonic polyposis given this genotype?

• A Total colectomy with ileorectal anastomosis (IRA) given low rectal polyp burden
• B Segmental colectomy targeting the most affected segment to minimize bowel loss
• C Surveillance alone with annual colonoscopy until symptoms develop
• D Restorative proctocolectomy (RPC) with ileal pouch-anal anastomosis (IPAA) due to high desmoid risk with IRA ✓

Explanation

FAP genotype-phenotype correlations are important: mutations between codons 1310–1444 (the genotype 3B region, centred around codon 1328) carry the highest risk of desmoid disease AND profuse rectal polyposis. Ileorectal anastomosis (IRA) is contraindicated when rectal polyp burden is high (>20 rectal polyps) or when genotype predicts severe rectal involvement; restorative proctocolectomy with IPAA is preferred. The desmoid risk itself also paradoxically argues against extensive intra-abdominal surgery in some centres, but the rectal polyposis severity drives the coloproctectomy decision in profuse cases.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.