[403] Indications for Kidney Fine Needle Aspiration (FNA) in the Era of Modern Renal Imaging Modalities.

Lina Liu, Ema Dragoescu. Virginia Commonwealth University Health System, Richmond

Background: Modern renal imaging modalities, particularly dedicated (thin-slice) renal CT scan with contrast and gadolinium-enhanced MRI, allow detailed evaluation of renal lesions, and the decision to follow-up or perform nephrectomy is often based on radiological studies alone without pathologic confirmation. Consequently, kidney FNA has become an uncommon procedure in our institution. The purpose of this study is to investigate the current indications for kidney FNA, assess its diagnostic utility, and evaluate cytologic/histologic correlation.
Design: All cases of kidney FNA performed in our center between January 2005 and August 2010 were retrieved. Clinical information, past medical history, radiologic findings, cytologic and subsequent histologic diagnoses, if available, were recorded.
Results: 41 cases (from 38 patients) of kidney FNA were identified: 23 (56%) were ultrasound-guided and 18 (44%) CT-guided. Indications for performing kidney FNA are summarized in table 1. The inconclusive solid masses were renal tumors with abnormal vascular pattern suggesting other entities in the differential diagnosis (oncocytoma, angiomyolipoma with minimal fat, urothelial carcinoma, or adrenal neoplasms).

Summary of clinical and radiologic indications for kidney FNA

Indications	Total number of cases
CT-scan favors renal cell carcinoma (RCC), but patient has prior history of other malignancy, extensive metastatic disease, or extensive local disease	17(41.46%)
Solid renal masses inconclusive on renal imaging	12(29.27%)
Abscess	4(9.75%)
Cystic lesions	3(7.32%)
Kidney masses on dialysis patients	3(7.32%)
Other (CT-scan favors lymphoma or urothelial carcinoma-1 case each)	2(4.88%)

In 29 cases (71%) a specific cytologic diagnosis was rendered. The nondiagnostic FNA samples (29%) consisted of foamy and hemosiderin-laden macrophages and normal renal elements. Histologic follow-up was available in 16 cases: 14 (87.5%) FNA diagnoses correlated with histology. Two cases (12.5%) were false negatives (FN): one FN case was Burkitt's lymphoma diagnosed on FNA as renal interstitial nephritis and the other was a clear cell RCC not sampled by FNA.
Conclusions: Kidney FNA represents a useful diagnostic tool in selected clinicoradiographic dilemmas. In our series the majority of FNAs (70.73%) were requested due to either the presence of confounding clinical factors with otherwise characteristic renal CT findings or inconclusive solid masses on renal imaging. The cytologic/histologic correlation is excellent (87.5%) with no false positive cases, however nondiagnostic samples are not uncommon.
Category: Cytopathology

Wednesday, March 2, 2011 1:00 PM

Poster Session VI # 79, Wednesday Afternoon