Presence of an abdominal effusion is a typical presenting sign associated with ovarian carcinoma (OC) in dogs.Objectives
The aims of this study were to describe the cytologic features of effusions associated with OC and to evaluate the diagnostic accuracy of such features for the diagnosis of OC in dogs.Methods
Cytologic evaluations of 7 OC-associated peritoneal effusions in dogs were used to define cytomorphologic features of this neoplasm. Then, in a blinded study to evaluate the accuracy of these features in identifying OC, 2 independent board-certified clinical pathologists reviewed 82 pleural, pericardial, and abdominal effusions resulting from OC (n = 7), other neoplasms (n = 40), and non-neoplastic disorders (n = 35). The clinical pathologists were instructed to identify all samples containing papillary structures typically seen in OC and then apply the cytomorphologic criteria determined in the first part of the study to diagnose OC.Results
Effusions associated with OC contained blood and had moderate to high cellularity, with neoplastic cells arranged in a prominent papillary pattern in which intercellular spaces were not clearly evident. Individual cells were approximately 30 μm in diameter, with mild anisocytosis and anisokaryosis, moderate amounts of pale blue cytoplasm, and round to oval paracentral nuclei with fine chromatin and poorly distinct small nucleoli. Using these cytologic features to identify OC in the 82 effusions, sensitivity was 86% and 100% and specificity was 57% and 97% for the 2 clinical pathologists. Overall accuracies in distinguishing OC from other effusions were 98.8% and 93.9%.Conclusion
Based on this preliminary study, effusion cytology from intact female dogs affected by OC appears to be useful in suggesting a diagnosis of neoplasia. The presence of cells with a prominent and uniform papillary pattern in peritoneal and pleural effusions in dogs with appropriate signalment and clinical signs should prompt a search for primary ovarian neoplasia.