[A Case of Central Diabetes Insipidus That Was Caused by Pituitary Metastasis of Lung Adenocarcinoma and Was Controlled by Radiation Therapy].

Background: Pituitary metastasis of lung cancer is rare; however, it often causes diabetes insipidus. Although the majority of such patients are treated with radiation therapy, it remains unclear whether diabetes insipidus can be controlled by radiation therapy.

Case: A 72-year-old man was admitted to our hospital for hemosputum, headache, and polyuria. A chest CT scan showed a 3.0 cm mass in the left upper lobe of his lung. Bronchofiberscopy results confirmed the pathological diagnosis of lung adenocarcinoma. Based on the findings from PET-CT, head MRI, and endocrine tests, the diagnosis of lung adenocarcinoma( cT1bN0M1b, stage IV)accompanied with central diabetes insipidus caused by pituitary metastasis was made. Oral administration of desmopressin reduced urine volumes; however, chemotherapy for achieving stable disease in the primary tumor was ineffective in controlling the symptoms of diabetes insipidus. Chemotherapy was discontinued after 4 months because of severe hematological toxicity. During 2 months after the cessation of chemotherapy, polyuria worsened and, therefore, radiation therapy for pituitary metastasis was started. Following the radiation therapy, an apparent reduction in urine volume was observed.

Conclusion: Our experience of this case suggests that radiation therapy for pituitary metastasis should be considered at the time when diabetes insipidus becomes clinically overt.