Which grading scheme was developed for dermal mast cell tumors?

• A. Kiupel grading scheme
• B. Patnaik grading scheme
• C. Fletcher grading system
• D. WHO grading system

Answer: (B)

Patnaik’s grading scheme was developed specifically for canine cutaneous (dermal) mast cell tumors and classifies tumors into three grades based on how differentiated the mast cells are and how aggressively the tumor invades surrounding tissue. Well-differentiated tumors have a more uniform appearance and lower mitotic activity, representing a more favorable prognosis; moderately differentiated tumors show intermediate features and variable behavior; poorly differentiated tumors are highly atypical with many mitotic figures and significant invasion, carrying the worst prognosis. This three-tier system provided the classic framework for prognosis and treatment decisions in dermal MCT for many years. Later schemes, like Kiupel’s two-tier system, were introduced to improve reproducibility, but the original dermal-specific grading developed for this context is Patnaik’s.