赤血球増多症を伴ったエリスロポエチン産生腎細胞癌の1例

Abstract

46歳男.主訴は肉眼的血尿, 左腰背部痛.腹部超音波検査で左腎下極に直径約8cmの腫瘤性病変を認めた.腎MRIで腫瘤中央部はT1でlow intensity, T2でhigh intensityでの出血と考えられた.辺縁部はT1, T2共にhigh intensityで, 血中エリスロポエチン高値を伴う赤血球増多症とCRP高値を認めた.傍大動脈リンパ節に多発性リンパ節腫大を有している為, T2N2M0 IV期の赤血球増多症を伴った左腎腫瘍と診断された.肉眼的血尿は止血剤投与でまもなく消失した.赤血球増多症の増悪傾向を認めた為, 約800mlの瀉血を施行し根治的左腎摘除術を施行した.左腎下極は手拳大に腫大し, 傍大動脈リンパ節腫大を認めた為, リンパ節郭清を施行した.術後は順調に経過して術前に認められた赤血球増多症や血中エリスロポエチン高値は術後正常化した.他に赤血球増多症の原因を認めず, 臨床経過より後述するエリスロポエチン産生腫瘍の診断基準を満たすことから, 本症例をエリスロポエチン産生腎細胞癌と診断した

The patient was a 46-year-old man with gross hematuria and left lumbar pain. Computed tomography revealed a large left renal tumor with hemorrhage. Serological examination revealed polycythemia and a high erythropoietin level. After left radical nephrectomy, polycythemia and serologically high level of erythropoietin disappeared. Histopathological findings showed renal cell carcinoma composed of spindle cells. Based on the above mentioned clinical course, we diagnosed this case as erythropoietin-producing renal cell carcinoma with polycythemia. It is suggested that erythropoietin not only causes polycythemia but also stimulates proliferation of the tumor, because the majority of erythropoietin-producing renal cell carcinomas have been reported to be highly advanced. This patient had no evidence of disease one year after the operation.