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Objectives The primary objective of this study was to retrospectively assess the diagnostic utility of feline renal fine-needle aspiration cytology by assessing diagnostic yield, cytologic characteristics and diagnostic accuracy. The secondary objective was to characterize ultrasonographic features of sampled kidneys to determine if they influenced diagnostic yield. Methods Slides, images and patient data were collected from the University of Minnesota Veterinary Medical Center database. Slides were designated as diagnostic or non-diagnostic. Non-diagnostic slides were used in calculating diagnostic yield and excluded from other analysis. Slides were evaluated for cytologic characteristics and assigned a single primary diagnosis. Ultrasound still images were evaluated for descriptive characteristics and characteristics of specific lesions were described. Cases with confirmatory testing were used to determine diagnostic sensitivity, specificity and positive and negative predictive values for detecting neoplasia. Results Of 96 cytologic submissions available for review, diagnostic yield was 68%; 48% of samples were at least moderately cellular. Of 87 cases with ultrasound data, kidneys showing subcapsular renal infiltrate, diffuse renal enlargement without pelvic dilation and infiltrative/nodular change were more likely to yield diagnostic samples. Of 12 confirmed cases, cytology was 100% sensitive and specific for the detection of neoplasia (four round-cell tumors and two carcinomas). Three cases with non-neoplastic histologic diagnoses were considered cytologically normal, two incorrectly diagnosed the pathology present, and one correctly diagnosed the pathology. While some imaging characteristics were more commonly seen in neoplastic vs non-neoplastic lesions, the sample size was insufficient for definitive correlation. Conclusions and relevance This is the first major analysis of feline ultrasound-guided renal fine-needle aspiration cytology. This technique generates adequate samples for interpretation at rates comparable to other soft tissues and is most useful in the diagnosis of neoplasia. Some imaging characteristics are indicative of the likelihood of obtaining an adequate sample for cytologic interpretation. [ABSTRACT FROM AUTHOR]

OBJECTIVE To describe cytologic characteristics of renal fine-needle aspirate (FNA) samples from dogs, evaluate proportions of cytologic specimens deemed adequate for interpretation (diagnostic yield), assess diagnostic utility of cytologic examination for neoplastic and nonneoplastic diseases, and characterize ultrasonographic features of evaluated kidneys to determine whether the imaging characteristics could be used to inform cytologic interpretations. DESIGN Retrospective, observational study. SAMPLE 102 cytologic specimens and 97 ultrasonographic studies from 100 dogs. PROCEDURES Medical records were reviewed to identify dogs that underwent ultrasound-guided renal FNA. Slides were categorized as adequate or inadequate for interpretation; adequate slides were used for retrospective cytologic diagnosis. Sensitivity, specificity, and predictive values of cytologic examination for detection of neoplastic and nonneoplastic conditions were calculated by comparison with histologic or lymphoid cell clonality assay results. Ultrasonographic characteristics of neoplastic and nonneoplastic renal lesions were described. RESULTS 74 of 102 (72%) specimens had slides adequate for interpretation; 26 were included in the diagnostic accuracy analysis. Sensitivity of cytologic examination was 78% and 50% for detection of neoplastic and nonneoplastic conditions, respectively, with specificities of 50% and 77%, respectively; sensitivity for detection of lymphoma was 100%. Ultrasonographic appearance of kidneys with confirmed neoplasia varied; masses were most commonly found in kidneys with carcinoma (5/5), lymphoma (5/7), or other neoplasia (3/4) and absent in kidneys with nonneoplastic conditions (n = 5). CONCLUSIONS AND CLINICAL RELEVANCE Renal FNA specimens were adequate for interpretation at rates comparable with those reported for other organs and were considered clinically useful for diagnosis of neoplasia. Imaging characteristics may potentially aid differentiation between neoplastic and nonneoplastic lesions; however, further investigation is needed. [ABSTRACT FROM AUTHOR]