膜性腎症を合併した肺腺扁平上皮癌の1例

摘要

背景．肺癌に膜性腎症を合併する症例はしばしば経験されるが，その因果関係については明確にされていない．症例．69歳，男性．右背部痛を主訴として来院した．胸部X線写真にて右上実に異常陰影を指摘され，気管支鏡下生検にて低分化肺扁平上皮癌（T2N3M0StageⅢB）と診断された．また蛋白尿もみられ，入院時の1日尿蛋白量は2.6gであった．cytOkeratin 19 fragment（CYFRA21-1）は39.1ng/mlと高値であった．carboplatinとdocetaxelhydrateによる化学療法を5クール施行し，腫瘍は縮小し，CYFRA21-1も低下（7.1ng/ml）するとともに，尿蛋白量も減少した（0.1g/day）．退院後，肺癌は再び増大し，最終的には呼吸不全に陥り死亡した．剖検によって，原発巣の組織型は腺扁平上皮癌，腎病変は膜性腎症であることが示された．結論．自験例は尿蛋白の経過がCYFRA21-1の変化と一致した膜性腎症合併肺腺扁平上皮癌症例であり，肺癌と膜性腎症との関係を考察する上で興味深い症例と考えられた．Background. Although there are some reports of lung cancer complicated by membranous nephropathy, the mechanism of their simultaneous occurrence is not well understood. Case. A 69-year-old man was admitted to our hospital complaining of right back pain. Chest X-ray examination revealed a massive shadow in the right upper lobe. The tumor mass was diagnosed as poorly differentiated squamous cell carcinoma of the lung (T2N3MO Stage ⅢB). Urinary protein excretion was 2.6g/day. The serum level of cytokeratin 19 fragment (CYFRA21-1) was 39.1ng/ml. Combination chemotherapy with carboplatin and docetaxel hydrate was started. A partial response was finally obtained after five courses. Serum level of CYFRA21-1 and amount of urinary protein excretion were decreased to 7.1ng/ml and 0.1g/day. After discharge, the lung cancer progressed and he finally died of respiratory failure. Adenosquamous carcinoma of the lung and membranous nephropathy were proven by autopsy. Conclusion. This case appears to have exhibited parallel time courses of progression of adenosquamous carcinoma of the lung, membranous nephropathy and changes in serum CYFRA21-1 level. This is of interest in considering the mechanism of the complication of lung cancerby membranous nephropathy.