Fine-needle aspiration of renal masses in adults: Analysis of results and diagnostic problems in 108 cases

Fine-needle aspiration (FNA) biopsy of the kidney has a traditionally well- defined role irt the diagnosis and treatment of renal lesions. Recent impro vements in renal imaging techniques have also brought renal FNA to the fore front, since small and asymptomatic renal masses are increasingly being det ected. Before the physician institutes a treatment plan, such lesions usual ly require a definitive diagnosis that is best provided by FNA. To assess v arious aspects of renal FNA, including specimen adequacy questionable cytol ogic patterns, and diagnostic pitfalls, we retrospectively evaluate our exp erience with 108 FNA biopsies performed for the evaluation of renal masses in adults. For each case, the smears were reviewed and correlated with tiss ue sections from cell blocks, surgical specimens, or autopsy material, when available. The cytologic diagnoses were confirmed by cell block (59 cases) , nephrectomy or autopsy (35 cases), or clinical follow-up. Of the 108 FNA biopsy samples, 17 showed evidence of blood, blood, soft tissue, necrotic m aterial, glomeruli, or tubular cells and were classified as unsatisfactory. The following diagnostic categories were noted in the 91 satisfactory aspi rates: renal abscess (four cases), benign cyst (30 cases), suspicious lesio ns (11 cases), and malignant lesions (46 cases). 62 four cases of renal abs cess, FNA Sound abundant clusters of neutrophils. For the 30 cases interpre ted on cytologic evidence as benign cysts, the diagnosis was confirmed in 2 8 cases; the two remaining cases were acquired cystic kidney and cystic ren al-cell carcinoma, respectively. Among the 11 suspicious lesions, the final diagnoses were one benign simple cyst, one angiomyolipoma, two multilocula r cystic nephromas, Two adult polycystic kidneys, one acquired cystic kidne y, three cystic papillary renal-cell carcinomas, and one solid renal-cell c arcinoma. Cases classified as suspicious shared characteristic cytologic pa tterns that distinguished them from simple benign cysts and from classic re nal-cell carcinoma. Among the 46 malignant lesions, as evidenced oil cytolo gic examination, 27 were renal-cell carcinomas, Jive were transitional-cell carcinomas, four were lymphomas, one was a small-cell undifferentiated car cinoma, and nine were metastatic carcinomas. False-positive or false-negati ve cases were not encountered in this category In conclusion, FNA is an exc ellent method to diagnose space-occupying lesions of the kidney. For cystic lesions, cytologic-radiographic col relation is needed to avoid misinterpr etation. Our study defines a spectrum of suspicions patterns characteristic of a group of renal lesions that are distinct from both benign simple cyst and straightforward renal malignancy (C) 1999 Wiley-Liss, Inc.