Mast cell tumors are the most common type of cutaneous tumor in dogs, representing 7% to 21% of all skin tumors in this species.1,2 The most common clinical finding is a solitary cutaneous MCT; however, approximately 11% to 14% of dogs have multiple cutaneous MCTs.3,4 Mast cell tumors have a biologically variable clinical course, ranging from benign to aggressive behavior and outcome. Many prognostic factors have been used to predict the biological behavior of MCTs. Variables such as histologic grade, anatomic location, growth rate, recurrence, and the presence of clinical signs are among the more commonly used prognostic factors.1,2,5–8
Clinical stage is also predictive of outcome.1,6,9 The current World Health Organization TNM classification of MCTs in dogs has multiple dermal tumors listed as stage III disease, suggesting a poor prognosis.10 Data supporting this current classification are lacking. There have been only a few references11–14 to multiple cutaneous MCTs in the veterinary literature, all of which suggest that there is no difference in outcome between patients with multiple MCTs and those with solitary MCTs.
We hypothesized that multiple cutaneous MCTs would have a benign clinical course, behaving more like discrete primary skin tumors rather than a form of metastasis or an advanced stage of disease. The purpose of the study reported here was to determine prognostic factors associated with outcome in dogs with multiple cutaneous MCTs treated with surgery with or without adjuvant treatment. The biological behavior of MCTs was also evaluated.
Mast cell tumor
Tumor node metastasis
Colorado State University Veterinary Teaching Hospital
SPSS 13.0, SPSS Inc, Chicago, Ill.
Prizm 4.0, Graph Pad Software, San Diego, Calif.
GB-Stat, version V6.5, Dynamic Microsystems, Silver Spring, Md.
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