Needle tract seeding following aspiration of renal cell carcinoma.

A case of tumor implantation along the needle tract 20 months after needle aspiration of a renal cell carcinoma is reported. This rare but possible complication of needle aspiration should not discourage its use in the evaluation of renal mass lesions. Needle aspiration should be reserved for those patients in whom the clinical findings, roentgenograms and sonography indicate a benign process (that is to confirm that the mass is benign).