Beclin-1 testing is aimed at guiding therapy decisions for which Patnaik grade tumors?

• A. Grade II dermal MCTs and subcutaneous MCTs with mitotic counts near 4
• B. Grade I cutaneous MCTs
• C. Grade III visceral MCTs
• D. All Patnaik grades equally

Answer: (A)

Beclin-1 testing is used to refine prognosis in canine mast cell tumors that fall into an uncertain middle ground. Specifically, it helps guide therapy for Patnaik grade II dermal MCTs and subcutaneous MCTs when the mitotic count is near 4. That mitotic threshold sits at a prognostic cusp: purely histologic grading can label some tumors as grade II, but their behavior may be closer to more aggressive disease. Beclin-1, related to autophagy pathways, provides additional prognostic information that helps decide how aggressive to be with treatment—whether to pursue wider surgical margins, adjuvant therapy, or closer monitoring.

In contrast, very low-risk cases like grade I cutaneous MCTs typically don’t require this extra testing, and high-risk cases such as grade III visceral MCTs are managed based on their clear high-risk biology rather than this biomarker. So the test is specifically aimed at informing decisions for grade II tumors that sit near the border with higher-grade disease.