A case report: Synchronous occurrence of clear cell renal cell carcinoma and low-malignant-potential multicystic renal tumor within the same kidney

The simultaneous occurrence of different tumor types in the same kidney is relatively rare. This report describes a 76-year-old male patient presenting with concurrent clear cell renal cell carcinoma (ccRCC) and multilocular cystic renal neoplasm of low malignant potential (MCRNLMP) in a single kidney. CT imaging revealed a solid mass in the upper pole and a Bosniak III cyst in the lower pole. The patient underwent radical nephrectomy, and pathological examination confirmed the coexistence of both lesions. This highlights the limitations of imaging diagnosis and underscores the critical importance of histopathological diagnosis for treatment decision-making. • The difficulty in differentiating MCRNL from cystic ccRCC based on imaging alone directly impacts surgical decision-making. • The therapeutic dilemma in choosing between nephron-sparing surgery and radical nephrectomy when multiple lesions of uncertain histology are present. • The importance of definitive histopathological examination in guiding prognosis and follow-up.