A case of Cowden's syndrome presenting with gastric carcinomas and gastrointestinal polyposis

Background: A 73-year-old white man was referred to a cancer genetics clinic for evaluation of a ∼20-year history of mixed upper and lower gastrointestinal polyposis, including hyperplastic, inflammatory and adenomatous polyps, colonic ganglioneuromas, and associated diffuse, esophageal glycogenic acanthosis. Two synchronous gastric carcinomas had been identified before referral and the patient had undergone a total gastrectomy, omentectomy and cholecystectomy. Multiple hyperplastic polyps and small, sessile polyps were also observed in the gastrectomy specimen. Investigations: History and physical examination, upper and lower gastrointestinal endoscopy and biopsy, genetic testing, molecular pathology investigations (immunohistochemistry), thyroid ultrasonography, fine-needle aspiration of a thyroid nodule. Diagnosis: Cowden's syndrome. Management: Genetic counseling, thyroidectomy, vitamin B₁₂ supplementation, continued endoscopic surveillance and genetic testing of at-risk family members.