Predictive ability of fine-needle aspirate cytology for incompletely resected mast cell tumor surgical sites

The goal of this study was to evaluate whether fine-needle aspirate cytology of a previous surgical site was predictive of recurrence for incompletely excised mast cell tumors (MCTs). Electronic medical records were searched for dogs diagnosed with MCTs; those with histologically confirmed, incompletely resected MCTs evaluated by scar aspiration cytology within 60 days after surgery were included for analysis. Variables were compared between groups using Fisher's exact test and logistic regression. Twenty-nine cutaneous and 7 subcutaneous tumors were evaluated. Local recurrence, confirmed by either histopathology or cytology, occurred in 13.8% of cases. No significant differences were identified for any variables other than surgical site cytology status. The negative predictive value of surgical site aspirate cytology without residual mast cell tumor was 93.5%, with an overall predictive accuracy of 88.9%. For the dogs evaluated in this report, surgical site aspiration cytology was predictive of local disease control for incompletely resected MCTs.