Fine needle aspiration biopsy of complex renal cystic tumors in the era of modern imaging modalities: where shall we go?

Abstract

Objective: To report on a series of fine needle aspiration (FNA) biopsies for preoperative diagnosis of complex cystic renal mass.

Study design: From August 2002 to February 2009, 32 patients with a complex cystic renal mass were studied. Tumor size ranged from 1.5-7.7 cm, with a median of 3.0 cm. Bosniak classification was 15 IIF, 12 III, and 5 IV. FNA biopsy was performed under CT guidance to obtain the fluid. Malignant and suspect cytological reports were considered as a positive diagnosis, and absence of epithelial cells as a negative diagnosis.

Results: Sufficient fluid was obtained in all cases. A positive preoperative diagnosis was found in 11 patients, and 21 cysts presented as absence of epithelial cells. Of the 26 patients who underwent surgery, pathology proved that there were 21 malignant and 5 benign cysts. Among the operated patients with a malignant cystic tumor, 11/21 (52.3%) presented a negative preoperative diagnosis. One preoperative positive diagnosis was proved to be a benign cyst. The accuracy of preoperative positive cytology was 10/11 (90.9%).

Conclusion: No difficulty was noticed in obtaining the fluid by FNA of a cystic small renal mass. A false negative diagnosis was due mainly to the absence of malignant cells in the fluid of cysts. Biomarkers in fluid shall be studied to solve the diagnostic problem.