[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.