Clear cell renal cell carcinoma presenting as isolated symptomatic lumbar vertebral metastasis: a case report

We report a rare case of clear cell renal cell carcinoma (ccRCC) initially presenting as an isolated symptomatic lumbar vertebral metastasis. A 62-year-old man presented with progressive low back pain radiating to the right lower extremity. Elevated prostate-specific antigen (PSA) levels initially raised strong suspicion for prostate cancer with bone metastasis. However, comprehensive multimodal imaging combined with histopathological evaluation ultimately established the diagnosis of right-sided ccRCC with metastasis to the fourth lumbar vertebra (L4). This case highlights the critical importance of a systematic and multimodal diagnostic approach for bone lesions of unknown primary origin, even in the presence of misleading tumor-specific indicators. We further discuss the diagnostic challenges associated with occult RCC, key differential diagnoses, the role of multidisciplinary team (MDT) management, and current combined therapeutic strategies for metastatic RCC. Clear cell renal cell carcinoma, Bone metastasis, Lumbar vertebra, Unknown primary tumor, Multimodal diagnosis, Multidisciplinary team.