前立腺小細胞癌の1例

Abstract

80歳男.主訴は排尿困難と頻尿であった.他院で前立腺癌と診断され, 抗アンドロゲン剤を8ヵ月間投与されていた.初診時, PSA14.4ng/mLと高値を示し, 前立腺生検では前立腺両葉から低分化型腺癌が検出された.4ヵ月後, PSAは24.8ng/mLとさらに上昇し, LH-RHアナログ製剤を投与した.PSAは順調に下降したが, 全身状態が悪化して, 診断後16ヵ月で死亡した.剖検でPSA染色陰性で, synaptophysin染色に陽性であった.強拡大像ではこれらの細胞は胞体が乏しく, 核は明瞭なクロマチンを持つが, 核小体ははっきりしなかった.同様の細胞は, 肺の一部, 膵の一部にも認められたが, 癌の占める部位が前立腺でもっとも大きいため, 前立腺原発小細胞癌と診断した.また, 両腎ともに広範に尿細管壊死に陥っており, 癌による播種性血管内凝固症候群が原因であると推測した

An 80-year-old man visited our hospital because of dysuria and pollakisuria. He had undergone anti-androgen therapy for prostate cancer for 8 months at another hospital. His serum prostate specific antigen (PSA) level was 14.4 ng/ml. We performed a prostate biopsy and identified poorly differentiated adenocarcinoma with Gleason score 4 + 5. After 4 months, his serum PSA level increased to 24.8 ng/ml, and we started maximum androgen blockade therapy using additional luteinizing hormone-releasing hormone (LH-RH) analogue. Subsequently, although his serum PSA level declined favorably, his condition worsened rapidly and he died at 16 months after the diagnosis. The autopsy pathology of his prostate revealed small cell carcinoma. We reviewed the initial biopsy specimens and found both small cell carcinoma and adenocarcinoma histologic types of prostate cancer.