[Paraneoplastic hyperthyroidism in a patient with metastasizing teratocarcinoma and excessively high HCG]

Clinically manifest hyperthyroidism is a rare paraneoplastic syndrome in patients with excessive HCG production due to testicular cancer. A 40-year-old patient with right testicular cancer (teratoma, embryonal cell carcinoma), diffuse pulmonary metastases and high serum HCG levels presented with symptomatic hyperthyroidism. The patient received immediately thyrostatic therapy and 4 cycles of PEI chemotherapy (Cisplatin, Etoposide, Ifosfamide). Thyroid function had returned to normal by the beginning of the second course of chemotherapy. After right orchiectomy and resection of residual pulmonary masses which revealed vital tumor cells, two additional courses of chemotherapy were performed. The patient is well and without evidence of disease 11 months after therapy. All patients with testicular cancer and excessive HCG production should be evaluated for biochemical and clinical signs of hyperthyroidism and treated accordingly with antithyroidal medication and immediate cytoreductive chemotherapy.