A man in his fifties had a medical checkup. Mucosal papillomatosis in his oral cavity and palmoplantar keratosis were observed. Esophagogastroduodenoscopy revealed multiple polypoid lesions both in the esophagus and stomach. In addition, colonoscopy showed schwannoma in the rectum. He underwent an operation for adenomatous goiter. At first his typical esophageal multiple polypoid lesion was a diagnostic cue to Cowden disease (CD). Other clinical findings convinced us that he was suffering from CD. He was, then, diagnosed as CD according to the criteria of International Cowden Consortium although he had no family medical history suspicious of CD. Interestingly, genetic testing revealed that the patient had a germline mutation in exon5 of PTEN on chromosome 10. It was a point mutation of C to T transition at codon130, resulting in nonsense mutation (CGA→TGA). A close follow-up, especially cancer surveillance, is necessary for him since CD is associated with a high risk of developing malignant disease. It is noted that the typical esophageal features can be a diagnostic cue to CD, as shown in the present case.