本文报道一例因发现左肾巨大积液继而确诊左肾盂恶性肿瘤的病例。患者因"头晕伴记忆力减退3月余，左侧腰痛、排尿困难2 d"入广州医科大学附属第三医院就诊。CT显示左肾巨大积水，行左肾穿刺造瘘后症状缓解出院。后于外院行PET-CT显示左肾上组肾盏区域两枚结节状代谢增高影，倾向于尿路上皮癌。遂再次入我院泌尿外科，左肾造瘘引流液的液基细胞学可见异型细胞，考虑高级别尿路上皮癌。因患者年龄较大，基础疾病多，与患方沟通后决定予免疫治疗。患者于我院先后行5次"替雷利珠单抗"免疫治疗。经过治疗后，患者肿瘤缩小，引流液、尿液颜色变清，无肉眼血尿。经广东省医学会泌尿外科疑难病例多学科会诊，专家建议可再次与患方沟通行根治性手术，免疫治疗为可选择方案。经与患方沟通后，患方考虑继续采用免疫治疗。继续免疫治疗3次后，复查尿液液基细胞学阴性。治疗过程中患者无明显不良反应。因此，对于高龄、基础疾病较多、一般情况较差的上尿路尿路上皮癌患者，除根治性手术外，免疫单药治疗为可选择的治疗方案。

This article reports a case of diagnosed left renal pelvis malignant tumor due to the discovery of massive fluid accumulation in the left kidney. The patient was admitted to the Third Affiliated Hospital of Guangzhou Medical University for treatment due to dizziness and memory loss for more than 3 months, left lower back pain, and difficulty urinating for 2 days. CT scan showed huge hydronephrosis in the left kidney. Symptoms improved after left kidney puncture and fistula, and the patient was discharged. Later, a PET-CT scan was performed in an external hospital, revealing two nodular metabolic hyperintensities in the renal calyx area of the upper left kidney, indicating a tendency towards urothelial carcinoma. Upon re admission to the Urology department of our hospital, atypical cells were observed in the liquid based cytology of the left renal fistula drainage fluid, suggesting high-grade urothelial carcinoma. Considering that the patient is older and has multiple underlying diseases, after communicating with the patient, immunotherapy has been decided. The patient underwent 5 rounds of immunotherapy with Tirizizumab in our hospital. After treatment, the patient's tumor shrank, the color of the drainage fluid and urine became clear, and there was no visible hematuria. After multidisciplinary consultations on difficult cases in the urology department of Guangdong Medical Association, experts suggest that the patient undergo radical surgery again, and immunotherapy is an optional option. After communicating with the patient, they consider continuing immunotherapy. After continuing immunotherapy three times, the urine based cytology test was negative. During the treatment process, the patient had no significant adverse reactions. Therefore, for elderly patients with upper urinary tract urothelial carcinoma who have multiple underlying diseases and generally poor conditions, immune monotherapy is an optional treatment option in addition to curative surgery.