[A case of small cell lung cancer associated with diabetes insipidus and Cushing's syndrome].

: A 62-year-old male with small cell lung cancer (SCLC) associated with Cushing's syndrome and diabetes insipidus (DI) is reported. The patient was referred to our hospital for treatment of SCLC. A diagnosis of paraneoplastic Cushing's syndrome was made on the basis of an elevated serum ACTH (623.5 pg/ml) level, elevated excretion of urinary 17-OHCS (18.01 mg/day), obesity, hypertension, hyperglycemia, persistent hypokalemia, alkalosis, and no history of diabetes mellitus. He was also diagnosed as having DI based on polyuria and polydipsia, low specific gravity of the urine (1.007-1.010), low serum ADH (1.4 pg/ml) level, normal plasma osmolarity (29 mOsm/kg H2O), and the results of water deprivation test. DI and a left visual field defect was suggestive of metastasis to the pituitary region, but no lesion was detected by either CT scan or MRI scan. The patient failed to show a good response to intensive chemotherapy, and died of the tumor five months after commencing chemotherapy. Post-mortem examination revealed metastases to the hypothalamic-neurohypophyseal region, lungs, liver, adrenal glands, bone, bone marrow, and hilar and mediastinal lymph nodes.