Fine-needle aspiration of XXXX . Morphologic spectrum and diagnostic problems in 41 cases.

@entity8 @entity5409 @entity66 @entity5 @entity1358 @entity45 @entity703
Although imaging studies show the nature of most @entity8 (RCs), many RCs require fine-needle aspiration (FNA) for accurate diagnosis. Interpretation of the FNAs remains challenging. The FNA specimens of 41 RCs were reviewed and correlated with imaging studies. Final diagnoses for 30 cytologically benign lesions were simple cyst (28), acquired @entity5409 (1), and @entity703 (1). The fluid from the benign cysts displayed macrophages, epithelial cells from the cyst lining, tubular cells, neutrophils, and Liesegang rings. Fluid from the acquired @entity703 showed features similar to those of the benign cysts. The 9 cases with "suspicious" cytology included 5 @entity5409 displaying rare but atypical epithelial cell clusters, 3 low-grade @entity1358 with many mildly atypical papillary clusters of epithelial cells, and 1 simple benign cyst with many tubular cells. The 2 cytologically malignant lesions were @entity1358 with @entity5 cells with partially clear cytoplasm and atypical nuclei admixed with abundant macrophages and lymphocytes; 1 case developed in a kidney with acquired @entity66 . @entity45 remain the most frequently aspirated RCs, but @entity5409 are increasingly recognized. Since many RCs are composed of independent loculi, a nonrepresentative sample is a potential problem, and cytologic-radiologic correlation becomes mandatory. The "suspicious" patterns identified in this study should serve as diagnostic guidelines and set the foundation for future validation.
