Familial adenomatous polyposis (FAP) may be associated to several other pathologies involving multiple organs  and can significantly influence the disease prognosis. The objective of this study was to determine the frequency of extracolonic manifestations in patients with FAP.

This retrospective, descriptive study was conducted in the Departments of Gastroenterology and General Surgery at Mohamed Tahar Maamouri University Hospital, including 33 patients managed for FAP over a 16-year period (January 2005 to December 2024).

During the study period, 33 patients were included. The mean age was 48.2 years [18–78].A first-degree family history of FAP was present in 45.5% of patients. Regarding the circumstances of diagnosis, screening colonoscopy led to the diagnosis in 9 patients (28%).Fifty-five percent of patients presented with colorectal symptoms, including rectal bleeding (13 patients), abdominal pain (11 patients), diarrhea (5 patients), and alternating diarrhea and constipation (3 patients). In three cases, colonoscopy was performed to investigate anemia. One case was diagnosed after examination of the operative specimen from an emergency surgery for a perforated right-colon cancer presenting with peritonitis.

Regarding the assessment of extracolonic manifestations:Upper gastrointestinal endoscopy was performed in 93.3% of patients and revealed, in 9% of them, the presence of fundic gland polyps and subcentimetric tubular adenomas of the antrum.

Duodenoscopy was performed in 32 patients and revealed duodenal polyps in 5 cases. In three cases, two polyps smaller than 5 mm were observed, corresponding to low-grade tubular adenomas on histology, with a Spigelman score ≤ 4.A sessile 8-mm polyp without dysplasia was found in one patient.The fifth case involved a 20-mm pedunculated polyp with low-grade dysplasia and a Spigelman score of 7 (stage III). Resection was performed surgically via transverse duodenotomy during the same operative session as the total proctocolectomy. Histological examination revealed a tubular adenoma with low-grade intraepithelial neoplasia.

Concerning abdominal imaging, abdominal ultrasound was performed in 18 patients and CT scan in 23 patients. A single case of intra-abdominal desmoid tumor was identified. Abdominal imaging was unremarkable in 96.96% of cases. No pancreatic, gallbladder, or biliary tract tumors were noted.

Ophthalmologic examination including fundoscopy was performed in 31 patients and revealed congenital hypertrophy of the retinal pigment epithelium (CHRPE) in 4 patients, bilateral in two cases and unilateral in the remaining two.

Thyroid ultrasound, performed in 91% of patients, revealed abnormalities in 7 patients (24%):– A right-lobe nodule suggestive of papillary thyroid carcinoma, confirmed histologically.– Three nodules in another patient, classified as EU-TIRADS 4, with indeterminate cytologic atypia (Bethesda class III), managed with total thyroidectomy.– Other abnormalities consisted of nodules classified as TIRADS 2 and 3, requiring follow-up.

Long-bone radiography was performed in 76% of patients and showed an osteoma of the left ischiopubic ramus in one case. Skull radiography, performed in 15 patients, revealed osteomas in six cases (40%): cranial osteomas in three patients, two frontal sinus osteomas in one patient, and one orbital rim osteoma in another.

Dermatologic examination was performed in 30 patients and demonstrated sebaceous cysts on the back in two patients (6%).

In the absence of neurologic symptoms suggestive of brain tumors, no cerebral CT scan was performed.

 FAP is a rare and complex disorder. Diagnosis relies on family history assessment, colonoscopy, and confirmation by molecular testing. Several extracolonic manifestations may be associated with FAP. Gastroduodenal lesions and desmoid tumors should be investigated as a priority, as they significantly impact prognosis.