Diabetes Insipidus Induced by Metastasis of Lung Adenocarcinoma to Pituitary Gland : Case Report

摘要

Background. Brain metastasis is often seen in patients with lung cancer; however, the reported incidence of pituitary metastasis is rare. We present a case with central hypopituitarism secondary to pituitary metastasis from lung cancer. Case. A 78-year-old woman had been receiving treatment on an outpatient basis at a local hospital for the control of diabetes mellitus since 1998. A chest roentgenogram revealed a huge mass in the middle lung field of the left lung in February, 2006 and she was referred to us. A bronchoscopic biopsy in March revealed adenocarcinoma. Systemic examinations showed multiple lung metastases and bone metastases, and brain MRI also showed focal metastasis to the right occipital lobe, thus indicating a clinical stage of T4N3M1 (stage IV). She was admitted to our department due to severe appetite loss for 1 week. She complained of polyuria, thirst, and polydipsia. We performed a hematological examination including basal endocrinological conditions, a high concentration saline loading test, the response to desmopressin administration, and the findings of brain MRI, which led to a diagnosis of metastasis of lung cancer to the pituitary gland with central diabetes insipidus. Although chemotherapy did not improve the symptoms of diabetes insipidus, the intranasal administration of desmopressin improved them. Her appetite loss promptly improved after the administration of desmopressin. Conclusion. We should suspect the possibility of a metastatic pituitary tumor in a patient has diabetes insipidus. If such tumors can be accurately identified, appropriate treatment can result in an improvement in the quality of life for patients with advanced lung cancer. © 2007 The Japan Lung Cancer Society. 背景．肺癌の脳転移は高い頻度で認められるが，下垂体に転移することはまれである．今回われわれは下垂体転移により中枢性尿崩症を呈した症例を経験したので報告する．症例．症例は78歳女性．1998年より糖尿病の加療のために近医へ通院していた．2006年2月，胸部X線写真で左上肺野に腫瘤影を指摘され，当科に紹介となった．3月に気管支鏡検査を施行し，経気管支鏡的生検によって肺腺癌と診断した．全身精査の結果，多発肺内転移，骨転移，および頭部MRI検査にて右後頭葉への転移を認め，病期はT4N3M1（IV期）であった．入院1週間前から食欲不振が強くなったため，4月に精査加療目的で入院した．患者は多尿，口渇，多飲を認め，血液検査や高張食塩水負荷試験，酢酸デスモプレシン投与後の反応および頭部MRI所見により，転移性の下垂体腫瘍および中枢性尿崩症と診断した．化学療法は尿崩症症状に対して改善を示さなかったが，酢酸デスモプレシン投与によって食欲不振および患者のQOLは著明に改善した．結論．尿崩症患者をみた場合には，転移性下垂体腫瘍を鑑別にあげることが重要で，これに対する適切な治療により進行癌患者のQOLを改善できることが示唆された.