本文报道一例严重泌尿系感染伴淋巴结肿大患者的疑难病例。患者因"尿液浑浊4月余"入院，影像学提示左侧输尿管管壁增厚伴左肾重度积液，PET/CT显示左肾、输尿管及膀胱多处代谢活跃灶，同时左肾门区及腹主动脉旁多个淋巴结代谢活跃（SUV_max 9.8），难以鉴别转移性淋巴结与炎性淋巴结。四次尿液细胞学检测均未找到癌细胞。结核相关检查结果为阴性。经广东省医学会泌尿外科疑难病例多学科会诊讨论，行腹腔镜下左肾输尿管切除+腹主动脉旁淋巴结活检术，术后病理证实为左肾积脓、左肾结石，排除恶性肿瘤。本文探讨了尿路上皮癌淋巴结转移与炎性淋巴结的鉴别诊断策略。

This article reports a challenging case of severe urinary tract infection accompanied by lymphadenopathy. The patient was admitted with a chief complaint of "cloudy urine for over four months." Imaging revealed thickening of the left ureteral wall with severe hydronephrosis of the left kidney. PET/CT demonstrated multiple metabolically active foci in the left kidney, ureter, and bladder, along with metabolically active lymph nodes in the left renal hilum and para-aortic region (SUV_max 9.8), making it difficult to differentiate between metastatic and inflammatory lymph nodes. Four urine cytology tests failed to detect cancer cells. Upon the multidisciplinary consultation on difficult cases in Guangdong Urological Association, consultation, the patient underwent laparoscopic left nephroureterectomy with para-aortic lymph node biopsy. Postoperative pathology confirmed left pyonephrosis and nephrolithiasis, ruling out malignancy. This article discusses the differential diagnostic strategies for distinguishing between lymph node metastasis from urothelial carcinoma and inflammatory lymphadenopathy.