Solitary vertebral metastasis of unknown primary renal cell carcinoma treated with surgical resection plus tyrosine kinase inhibitor: A case report.

INTRODUCTION

Although 25-30 % of renal cell carcinomas (RCC) might be diagnosed in metastatic stage, occurrence of metastatic renal cell carcinoma (mRCC) as a cancer of unknown primary site (CUP-mRCC) is extremely rare. Here, we present a case of vertebral mass causing radicular pain that has been diagnosed to be mRCC through core needle biopsy while no renal mass has been found during serial imaging.

CASE PRESENTATION: A 60-year-old woman presented with severe lumbar pain radiating to left leg. Lumbar X-ray suggested a mass in second lumbar vertebra which was confirmed by MRI. Biopsy showed that the mass was clear cell RCC. Abdominopelvic CT scan and other metastatic work-up found no primary source for the cancer -in kidneys- nor any other metastasis. Tumor resection was performed followed by sunitinib administration. 3 months after the surgery, she is symptom free with no signs of disease progression nor kidney tumor.

DISCUSSION: 26 cases of CUP-mRCC has been reported in literature. Lymph nodes are the most commonly involved organ in CUP-mRCC. Exclusive bone involvement -similar to our case- have been reported in only 3 cases. No specific treatment guideline exists but surgery, systemic therapy, combination therapy, and radiotherapy have been used, with the first two items being the most commonly used ones.

CONCLUSION

Tumor resection plus sunitinib seems to be a reasonable option in solitary CUP-mRCC involving vertebral column. Our patient is symptom free and there are no signs of disease progression nor kidney cancer in follow-up imaging after 3 months of surgery.