転移巣骨生検によって診断が得られた前立腺癌の1例

Abstract

80歳男。入院前日に無症候性肉眼的血尿を認め入院した。表在リンパ節は触知せず, 直腸診では前立腺の軽度腫大を認めるが硬結, 圧痛は認めなかった。軽度貧血, 炎症反応上昇を認めPSA高値, 尿細胞診クラスIIであった。肉眼的血尿は保存的加療により数日で消失した。膀胱鏡, 静脈性腎盂造影を行ったが出血源を認めず抗血小板薬内服が血尿の原因と考え退院した。退院1ヵ月後採血でPSAが更に上昇したため骨盤MRI, 経会陰的前立腺生検を行った。MRIでは前立腺に悪性腫瘍を疑わせる所見を認めなかったがT2強調画像, 拡散強調画像で右恥骨に高信号を呈する領域が存在し転移性病巣と考えた。経会陰的前立腺生検を行ったが病理学的に明らかな悪性所見は認めなかった。しかしその後もPSAは上昇し初回生検3ヵ月後更に高値を示し, 骨シンチを施行したところEODの骨転移像が認められた。

An 80-year-old man visited our clinic with the chief complaint of asymptomatic macroscopic hematuria secondary to anticoagulant medicine. Although digital rectal examination was normal, a high serum prostate specific antigen (PSA) level (85.9 ng/ml) led us to perform sextant prostate biopsy, resulting in negative for cancer. Three months later, since the serum PSA increased to 169 ng/ml with high serum carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19-9 levels. Twelve-core prostate biopsy was performed again, but the result was negative. Pelvic magnetic resonance imaging (MRI) showed a metastatic lesion on the right pubic bone, which was biopsied, and turned out to be poorly differentiated prostate cancer in histology. Maximum androgen blockade failed to control PSA. Finally he died of pneumonia 55 days after the bone biopsy. To our knowledge, there were only two case reports diagnosed as prostate cancer by biopsies of the metastatic lesions in Japanese literature, but none in the English literature. These findings suggest that high serum levels of CEA and CA19-9 in patients with prostate cancer are indications of hormone-refractory prostate cancer resulting in poor prognosis.