Does routine colonoscopy help diagnose familial adenomatous polyposis in patients presenting with desmoid tumors but no gastrointestinal symptoms?

Purpose: Desmoid tumor (DT) is a rare myofibroblastic proliferative neoplasm, but can occur in up to 26% of patients with familial adenomatous polyposis (FAP). Therefore, DT may be an extraintestinal manifestation of FAP that precedes the development of advanced malignancies. The aim of this study was to identify the incidence of polyps in DT patients and investigate value of colonoscopy for diagnosis of FAP in DT patients without gastrointestinal symptoms.

Materials And Methods: The records of patients diagnosed with DT were retrospectively reviewed using the clinical data warehouse (CDW) system. Clinical data, including location of tumor, type(s) of treatment, and colonoscopic findings, were collected.

Results: Sixty-five patients were diagnosed with DT during the study period; 10 patients received colonoscopies before diagnosis of DT, and 20 patients received colonoscopies after diagnosis of DT. The mean age at diagnosis of DT was 41.9 ± 16.7 years old (range 17-74). Most tumors were extra-abdominal (n = 24, 80.0%), and fewer were intra-abdominal (n = 4, 13.3%) or in an abdominal wall (n = 2, 6.7%). The colonoscopy results revealed one or two tubular adenomas in 11 patients (36.6%), although none of the patients had colorectal polyposis or colorectal cancer.

Conclusion: None of the patients in our study population had colorectal polyposis. Routine colonoscopy of DT patients without gastrointestinal symptoms seems to have low diagnostic yield for detection of FAP.