Solid renal masses in adults: image-guided fine-needle aspiration cytology and imaging techniques--"two heads better than one?".

We have compared the diagnostic accuracy of image-guided 25G-FNA (fine-needle aspiration) and imaging modalities in a group of 31 patients with solid space-occupying renal lesions. All patients had undergone total nephrectomy and histologic sections were available for review. By FNA there were 24 malignant diagnoses, I benign diagnosis, and 6 cases with yield inadequate for diagnosis. The FNA accuracy for malignancy was 100% with no false positive cases; cancer typing by FNA matched the final histologic diagnoses in 91.6% of cases. Sensitivity, specificity, positive predictive value, and negative predictive value were 80%, 14%, 80%, and 14%, respectively. Radiologically there were 26 diagnoses of malignancy, I of benignity, and 4 indeterminate lesions (IL). Accuracy for malignancy was 100%, with one false positive case; cancer typing matched the final histologic diagnoses in 84%. Sensitivity of imaging modalities was 86%, specificity 17%, positive predictive value 83%, and negative predictive value 20%. Four IL corresponded to renal cell carcinoma in the final histologic report: two IL had a previous diagnosis of malignancy by FNA, and the yield of two was inadequate for cytologic diagnosis. Both techniques have 100% accuracy for the diagnosis of malignancy. The sensitivity, specificity, positive predictive value, and negative predictive value of imaging techniques are slightly higher than those obtained by FNA. Imaging techniques and FNA of solid renal masses complement each other in IL and in nondiagnostic FNAs.