Introduction

Mast cell tumors account for approximately 20% of skin tumors in dogs and carry a wide range of biologic behavior. There are many proposed mechanisms of determining mast cell tumor prognosis, including several marketed “prognostic panels” which use histologic criteria, immunohistochemistry, and molecular tests to predict prognosis and guide treatment. The aim of this study is to retrospectively evaluate if these tests (Ki67, AgNOR, cKit PCR, and KIT IHC) provide prognostically significant information with regards to progression free interval and overall survival for completely excised low grade mast cell tumors in dogs.

Methods

A medical records search was performed from March 2018 and prior for cases with completely excised low- grade mast cell tumors treated with surgery alone for which histology blocks were still available. Ki67, AgNOR, cKit PCR, and KIT IHC were submitted on all histology samples and medical records were used to evaluate for disease recurrence and/or metastasis for the calculation of progression free interval and for overall survival.

Results

At the time of abstract submission 53 cases for a total of 67 tumors met the inclusion criteria. The majority were mixed breed dogs with a median age at diagnosis of 7.8 years. Median follow up time was 1.6 years. There were three reports of confirmed or suspected local recurrence and 18 instances of confirmed or suspected de novo mast cell tumors at a distant cutaneous site.

Conclusion

Prognostic significance of Ki67, AgNOR, cKit PCR, and KIT IHC is pending and will be available prior to presentation.

Funding Information

None.