A 38-year-old with FAP (APC mutation) undergoes proctocolectomy. Postoperatively, he develops a 3-cm mesenteric desmoid tumor causing ureteral obstruction. Which of the following best describes the biological behavior of desmoid tumors in FAP?
- A They are locally aggressive, histologically benign fibromatoses that can invade adjacent structures but do not metastasize ✓
- B They are malignant, frequently metastasize to liver and lungs
- C They regress spontaneously in most cases without treatment
- D They respond well to conventional chemotherapy with >80% complete response rate
Correct answer: A. They are locally aggressive, histologically benign fibromatoses that can invade adjacent structures but do not metastasize
Explanation
Desmoid tumors (deep fibromatoses) in FAP are locally aggressive mesenchymal neoplasms with no metastatic potential, yet they cause significant morbidity and mortality through local invasion of mesenteric vessels, ureters, and bowel. They are the second leading cause of death in FAP patients. Surgical excision carries high recurrence rates (50–80%). Treatment options include sulindac, anti-estrogens (tamoxifen), tyrosine kinase inhibitors (imatinib, sorafenib), and radiation; response rates to chemotherapy are modest.
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.