下垂体前葉機能低下症に対しホルモン補充療法が奏効した男性乳癌下垂体転移の1例

A Case of Pituitary Metastasis in a Patient with Male Breast Cancer Developing Anterior Lobe Dysfunction Successfully Treated by Using Hormone Replacement Therapy

Ⅰ．はじめに

　男性乳癌は比較的稀であり，さらに下垂体へ転移し尿崩症ではなく前葉機能低下症で発症することも稀である．今回，それらを合併した症例を経験し，神経内分泌学的病態と治療法についての考察を加えたので報告する．

　Male breast cancer is a rare disease and accounts for ＜1% of all breast cancers. Anterior lobe dysfunction of the pituitary gland is known to occur in only 15% of patients with pituitary gland metastasis, and diabetes insipidus occurs in 70% of patients in this subset. We report a case of pituitary metastasis in a patient with male breast cancer that resulted in anterior lobe dysfunction. A 64-year-old man presented with consciousness loss and gait disturbance. His serum sodium level was 117mEq/L. Magnetic resonance imaging revealed a suprasellar tumor that showed inhomogeneous enhancement and was attached to the optic chiasm. Diabetes insipidus was not evident at admission, but was observed immediately after the administration of the steroid hormone complement. The patient underwent subtotal resection of the tumor via a transsphenoidal approach. Pathological examination revealed metastasis from estrogen receptor-positive breast cancer. The patient underwent conventional post-operative radiotherapy combined with hormone replacement therapy and has remained free of symptoms for 16 months. Herein, we discuss the neuroendocrinology of and treatment for pituitary gland metastasis.