A 27-year-old female patient presented with multiple lipomas and cavernous hemangiomas of the skin, hemangioma of the parotid gland, polyps of the gastrointestinal tract and endometrial carcinoma. After 1 year the patient presented with papillary thyroid carcinoma and a diagnosis of Cowden syndrome (CS) was made. Genetic testing revealed a pathogenic PTEN gene mutation. Hereditary tumor syndromes, such as CS are underdiagnosed. Clinical management can be adjusted to the needs of CS patients only if an early diagnosis is made. In CS the risk for thyroid, breast and endometrial cancer is severely increased.