PTEN hamartoma tumor syndrome (PHTS) is a rare autosomal dominant syndrome with an estimated prevalence of ~ 1:200,000, caused by germline inactivating mutations or deletions in the PTEN tumor suppressor gene (10q23.31) or in other functionally related genes (e.g., PIK3CA, AKT1) [14]. Here, PTEN is linked to PTEN hamartoma tumor syndrome.