A case of small cell carcinoma of the kidney

Abstract

A 47-year-old man had a retroperitoneal tumor measuring 18 cm in maximum diameter of the left kidney that was diagnosed with computed tomography (CT)-guided needle biopsy as small cell carcinoma. Microscopically, the tumor cells showed immunohistochemical reaction for neural cell adhesion molecule antibodies. This patient with advanced renal small cell carcinoma and multiple metastatic lesions was treated with the first-line combination chemotherapy of cisplatin, etoposide and ifosphamide, which showed a partial response of primary renal tumor and a complete response of liver metastasis, and with the second-line chemotherapy of cisplatin and irinotecan, which showed a complete response of Virchow's nodal metastasis. Thereafter, in spite of salvage chemotherapy of amurubicin hydrochloride for persistent and refractory renal small cell carcinoma, he died 32 months after the first presentation due to local progression. However, combination chemotherapy of these anticancer agents made his prognosis more favorable than we expected before treatment. The extrapulmonary small cell carcinomas are generally known to be more aggressive and malignant than the lung small cell carcinomas, and small cell carcinoma arising from the kidney is an extremely rare malignant neoplasm, with only 34 cases reported in the English or Japanese literature. The prognosis of renal small cell carcinomas is currently limited as compared with the lung small cell carcinomas, and therefore a cumulative investigation of a larger number of cases treated with multidisciplinary modalities including combination chemotherapy is necessary.

47歳, 男性に左腎由来の最大径18cmの後腹膜腫瘍を認め, CTガイド下針生検にて小細胞癌と診断した。組織診断で, 腫瘍細胞は神経細胞接着分子抗体を用いた免疫染色に陽性であった。多発転移を伴う進行性腎小細胞癌の本患者は, cisplatin, etoposide, ifosphamideによるfirst-lineの多剤併用化学療法を施行され, 腎原発巣のpartial responseと肝転移巣のcomplete responseを得た。さらに, cisplatinとirinotecanを用いたsecond-lineの化学療法にて, Virchowリンパ節転移巣のcomplete responseを得た。その後, 執拗に残存し再燃する腎原発巣に対して, amurubicin hydrochlorideによるsalvage化学療法を施行したが, 初診より32ヵ月後に局所進展のため癌死した。しかし, 本症例については, これらの抗癌剤を用いた化学療法により, 治療前に予想した以上に患者の予後は良好なものとなった。一般的に肺外小細胞癌は, 肺小細胞癌よりも侵襲的で, より悪性度の高い腫瘍として知られている。その中でも, 腎由来の小細胞癌はきわめて稀な悪性新生物であり, 英文あるいは邦文論文報告も僅かに34件である。現況では, 腎小細胞癌の予後は, 肺小細胞癌の予後に比べて不良であり, 何らかの多剤併用化学療法を含めた集学的治療による, より多くの症例での治療経験の集積とその調査が必要である。(著者抄録)