PTEN also undergoes germline-inactivating mutations that are responsible for various human syndromes.83 The PTEN hamartoma tumour syndrome is a hereditary tumour syndrome that predisposes patients to benign and malignant breast, thyroid, renal cell and endometrial tumours.84 A recently published study demonstrated that the innate immune cells from patients with PTEN hamartoma tumour syndrome produce high levels of lactate.85 Lactate confers a pro-inflammatory phenotype of monocytes in the TME of PTEN-deficient thyroid cancer. The gene discussed is PTEN; the disease is thyroid cancer.