Male, 43 years old. Eight years ago ultrasound suggested an occupying lesion in the left kidney, the nature of which was to be determined. It has been untreated. In the last two months, he had left lumbar pain and intermittent hematuria in the naked eye. He came to the clinic. CT findings] Cortical stage Medullary stage Drainage stage Coronal position The left kidney was huge, mostly cystic in density, with heterogeneous enhancement, segregation and low-density necrotic areas were seen within, and the mass was mostly well-defined, with some infiltrative growth. The renal pelvis and calyces were compressed, invaded and filled. Only a small part of the lower kidney was normally enhanced. Preoperative CT diagnosis: 1. cystic renal carcinoma 2. renal multifocal cystic tumor Analysis: cystic occupying lesion of renal parenchyma, large. After enhancement, the cystic wall, separation and wall nodules are enhanced, and there are thick and thin separation within the cyst, and the mass has uneven density. This is a common manifestation of cystic kidney cancer. The disease history was long, up to eight years of occupancy, so the possibility of cystic tumor malignancy was considered. It is more difficult to differentiate multiatrial cystic tumor part from cystic renal carcinoma, but multiatrial cystic tumor is mostly seen in children. Pathology】 Gross and microscopic manifestations Gross: the mass was oval-like, with the envelope basically intact and the surface still smooth. Microscopically, the tumor cells were arranged in a papillary pattern, and the tumor cells were rectangular and polygonal, with abundant eosinophilic cytoplasm and significant heterogeneity. Pathological diagnosis: papillary renal carcinoma The incidence of renal papillary carcinoma is second only to renal carcinoma (clear cell carcinoma), accounting for about 15-20% of renal carcinoma. Renal cell carcinoma includes subtypes such as clear cell carcinoma, papillary carcinoma, spindle cell carcinoma and collecting duct carcinoma. Papillary carcinoma differs from clear cell carcinoma in onset, morphologic features, and prognosis. On CT, papillary carcinoma most commonly appears as a lesion with a lack of blood supply, which generally appears as a lesion with uniform density and clear margins, with mild enhancement after enhancement, unlike clear cell carcinoma with rich blood supply, which appears as fast in and fast out. Unlike clear cell carcinoma with rich blood supply, the latter has a fast-in and fast-out appearance. Papillary renal carcinoma grows slowly and has low malignancy and invasiveness.