OBJECTIVE: To identify and describe the frequency, histologic features, and clinical outcome of colon polyposis and neoplasia in Cowden syndrome - a rare familial hamartoma tumor syndrome associated with mutations in the PTEN gene. PATIENTS AND METHODS: Patients with a clinical diagnosis of PTEN hamartoma tumor syndrome-Cowden phenotype were retrospectively identified and studied. Only those who underwent colonoscopy or colon pathologic interpretation were included in the final analysis. RESULTS: From 1994 to 2009, 13 patients met study inclusion criteria. Of the 10 patients who underwent colonoscopy, 9 (90%; 95% confidence interval [CI], 57%-100%) had polyps, and 7 (70%; 95% CI, 39%-90%) were estimated to have more than 50 polyps. Pathologic findings of the colon were reviewed in 11 patients, and the spectrum of tumors included hamartomatous, inflammatory, adenomatous, ganglioneuromatous, hyperplastic, and juvenile polyps. Of the 13 patients, 2 (15%; 95% CI, 3%-43%) had left-sided adenocarcinoma without microsatellite instability. Five (38%) of the 13 patients underwent colectomy secondary to polyp dysplasia. CONCLUSION: Patients with Cowden syndrome have a heavy colon polyp burden with a wide pathologic spectrum, both benign and malignant. The colon polyposis results in a previously unreported morbidity with a high colectomy rate.
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