PTEN and Cowden disease: Cowden Syndrome (CS) is a rare autosomal dominant disorder characterised by multiple hamartomas and an increased risk of breast, thyroid and endometrial carcinomas [1,2] Germline mutations in the tumour suppressor gene PTEN (phosphatase and tensin homolog) chromosome 10q23.2, which codes for a lipid phosphate mediating cell cycle arrest and apoptosis, were first described in Cowden Syndrome[3] In the next years since PTEN had been identified as the major CS susceptibility gene[4], a number of inherited cancer and developmental syndromes were associated with germline PTEN mutations.