Nonaspiration fine needle cytology and its histologic correlation in canine skin and soft tissue tumors.

OBJECTIVE: To analyze the findings of nonaspiration fine needle (NAFN) cytology as compared with the histopathologic findings in evaluating canine skin and soft tissue tumors. STUDY DESIGN: NAFN (21-27 gauge) cytology wasperformed on 213 cases. Smears were air dried and stained by the Rosenfeld method (May-Grunwald-Giemsa modification). Histopathologic evaluation was available for comparison in 40% of cases. RESULTS: NAFN cytology and histopathology results were compared in 85 dogs. The size of the 117 lesions varied from 0.5 to 2 cm (n = 39), 2.1 to 5 cm (n = 43), and ≥5.1 (n=35). There were 22 nonneoplastic lesions, mostly inflammatory processes and cysts. Neoplastic lesions were classified as epithelial (36%), mesenchymal (30%), round cell tumor (n = 13%) and melanocytic (2%). Among 40 malignant lesions, mast cell tumor (n = 14) and hemangiopericytoma (n = 9) were the most frequent. Lipoma (n=14) and trichoblastoma (n=10) were the most common benign neoplastic lesions. Cytology showed sensitivity of 89%, specificity of 100%, positive and negative predictive value of 100% and 96%, respectively, and efficacy of 97%. CONCLUSION: NAFN cytology is extremely useful and accurate. It is safe and avoids the use of anesthesia. Further, it is easy to perform and noninvasive and usually provides a high-quality sample.