炎性肌纤维母细胞瘤是一种潜在或低度恶性的间叶组织肿瘤，临床少见；肾髓质间质细胞瘤是一种临床少见的肾良性肿瘤。同时合并这两种疾病者，尚未见文献报道，本文报道1例。患者因腰痛、血尿入院，术前MRI检查考虑肾盂癌可能性大。行机器人辅助腹腔镜根治性左肾输尿管切除术，术后病理示肾盂炎性肌纤维母细胞瘤合并肾髓质间质细胞瘤。术后随访6个月余，未见肿瘤复发或转移。“,”Inflammatory myofibroblastic tumor (IMT)is a potentially or low-grade malignant mesenchymal neoplasm, which is rare in clinic. Renomedullary interstitial cell tumor(RICT) is a clinically rare benign renal tumor. The combination of these two diseases in one patient has not been reported. A 25-year-old female patient was admitted to the hospital due to left back pain for 12 days and hematuria for 1 week. MRI of kidneys showed a mass in the left renal pelvis, which was considered as renal pelvic carcinoma. Urine cytopathological examination was negative. Robot-assisted laparoscopic radical left nephroureterectomy was performed. There was no tumor recurrence or metastasis during the follow-up for more than 6 months after operation.