Diagnostic accuracy of computed tomography-guided percutaneous biopsy of renal masses.

OBJECTIVE

Modern imaging modalities increase the detection of small (<or=4 cm) renal tumors, of which about 20% are benign. As a result, minimal invasive treatments, such as radiofrequency ablation and cryotherapy, and surveillance strategies are gaining popularity. Information that would be helpful when choosing the most appropriate management strategy for this patient group could be obtained from pretherapeutic image-guided biopsy.

METHODS

Under computed tomography (CT)-fluoroscopic guidance 78 patients with solid renal tumors prospectively underwent 18-gauge core biopsy. In addition, using the same sheath, fine-needle aspiration was taken in 44 patients and analyzed cytologically. The renal masses were subsequently removed surgically and evaluated histologically.

RESULTS

Mean patient age was 63+/-13.5 yr; mean tumor size was 4+/-1.8 cm. The sensitivity of core biopsy and fine-needle aspiration for the detection of renal cell carcinoma (RCC) was 93.5% and 90.6%, respectively; Fuhrman grade was correctly predicted in 76% and 28% and the correct histologic subtype was identified 91% and 86%, respectively. Cytology from fine-needle aspiration revealed a sensitivity in detecting malignant and benign lesions of 100% and 75%, respectively. Two of the renal tumors diagnosed as oncocytomas on core biopsy were hybrid tumors with scattered areas of oncocytomas and chromophobe RCC. Complications of CT-guided biopsy included one marginal pneumothorax, which resolved under conservative management, and four small perirenal hematomas detected at follow-up ultrasonography not requiring further therapy.

CONCLUSION

CT-guided percutaneous preoperative renal tumor biopsy had a high diagnostic accuracy, particularly in predicting malignancy.