Parathyroid adenoma and gastric carcinoma as manifestations of Cowden's disease.

Cowden's disease is a well-described clinical syndrome, the primary symptoms of which are orocutaneous hamartomas and disseminated gastrointestinal polyposis. In general, the gastrointestinal polyps are benign, and the incidence of malignant transformation is believed to be low. Other associated manifestations of Cowden's disease include breast cancer and thyroid disease (benign and malignant). A patient with previously unrecognized Cowden's disease underwent upper gastrointestinal endoscopy for surveillance of hyperplastic gastric polyps, and a gastric carcinoma in situ was detected. During the course of follow-up the patient was found to have primary hyperparathyroidism resulting from a parathyroid adenoma. Although several benign proliferative and malignant conditions are associated with Cowden's disease, neither parathyroid adenoma nor gastric carcinoma has been reported previously.