Anti-PIT-1 hypophysitis is a form of paraneoplastic syndrome defined by (1) the presence of acquired GH, PRL, and TSH deficiency; (2) the detection of anti-PIT-1 antibodies or PIT-1 reactive T cells in the circulation; and (3) the coexistence of thymoma or malignancy [54,65]. The gene discussed is POU1F1; the disease is thymoma.