Correlation between cytology and histopathology in the diagnosis of splenic tumours in dogs

Background: Cytology is commonly used as a diagnostic procedure to evaluate splenic masses in veterinary medicine. However, few studies have addressed the accuracy of cytology in the evaluation of splenic masses in a clinical setting. Objective: The purpose of this study was to compare the diagnostic accuracy of cytology, in comparison with histopathology, in a series of neoplastic lesions. Methods: Cytologic and histopathologic specimens of 67 splenic lesions from 67 dogs were retrospectively evaluated. Cytologic samples were obtained by FNA. Histopathology was evaluated from tissues collected by surgical biopsy or necropsy. Results: A cytologic diagnosis of neoplasia was obtained in 36 cases (33 true positive cases, 3 false positive cases). Sarcoma (20/67) and lymphoma (7/67) were the most common tumors cytologically diagnosed. 31 samples were cytologically classified as "negative for neoplasia” (12 true negative cases, 19 false negative cases). Cytology had an overall 67.2% (45/67) agreement with histopathological analysis. In diagnosing neoplasia, cytology had a sensitivity of 89%, a specificity of 80%, a predictive value of positive test of 91.2% and a predictive value of negative test of 38.7%. Conclusions: The results of this study confirmed cytology as a reliable and useful diagnostic procedure for the evaluation of splenic neoplastic lesions in canine small animal practice.