Cowden syndrome is a rare hereditary disease included within hamartoma-type gastrointestinal polyposis. It is characterised by associated mucocutaneous anomalies and by the extraordinary tendency to develop malignant neoplasia, mainly in the breast and thyroid. Early diagnosis of the syndrome and adequate tumoral screening in patients with mucocutaneous papillomatosis make it possible to make an earlier diagnosis of associated pathologies which have great morbidity when detected late. We present the case of a patient diagnosed with Cowden syndrome after consultation for labial papillomatous lesions of long evolution who was subsequently treated for breast and kidney cancer in initial stages. The correct diagnosis of a banal pathology of oral mucosa made it possible for us to take early action against the neoplastic pathology associated with this disease.