[SMALL RENAL CELL CARCINOMA PRESENTING WITH HUGE SACRALMETASTASIS: A CASE REPORT].

A 66-year-old man with buttock pain and intermittent claudication visited a nearby doctor. Magnetic resonance imaging revealed a tumor of 8 cm in diameter in his sacrum. He was referred to our hospital. Abdominal contrast enhanced computed tomography revealed a small mass of 2.5 cm in diameter on his left kidney and he was diagnosed with metastatic bone disease after needle tumor biopsy. However, needle biopsy of the renal tumor demonstrated no evidence of malignancy. As he rejected further examination, we started treatment using the tyrosine kinase inhibitor sunitinib. However, it had little effect on his sacral metastasis and he developed massive bowel bleeding twice. Extensive invasion from the sacral metastasis to the back side of the rectum was found on colonoscopy. The patient died 2 months after the introduction of sunitinib. The final diagnosis based on pathological autopsy was renal cell carcinoma with sacral metastasis.