Case of small cell lung cancer complicated with diabetes insipidus and Cushing syndrome due to ectopic adrenocorticotropic hormone secretion]

A 54-year-old woman had been given a diagnosis with scleroderma and interstitial pneumonia due to scleroderma when she was 45 years old. Thirst, with resulting polydipsia and polyuria (about 7 liters/day) were present since May, 2004, and bloody sputum appeared in June of 2004. The patient was admitted to our hospital. Chest CT examination showed multiple nodules in the bilateral lower lung field and multiple movable subcutaneous nodules on the abdomen. Small-cell lung cancer (metastases in the pituitary, subcutaneous tissue, and lungs) was diagnosed by transbronchial lung biopsy and subcutaneous nodule biopsy of the abdomen. The final diagnosis was diabetes insipidus and Cushing syndrome. Chemotherapy was done with CDDP and VP-16, which resulted in reduction of the tumor and improvement in endocrinological findings. Nevertheless, chemotherapy could not be continued because of infected bullae. The patient died of deteriorating illness after 91 sickness days. We concluded that this case was Cushing syndrome caused by ectopic adrenocorticotropic hormone-producing small cell lung cancer, and that it presented with diabetes insipidus because of pituitary metastasis. Therefore, when drastic endocrinological changes are found, it is important to examine for cancer, including lung cancer, as soon as possible.