This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Head & Neck, Subject name: Pathology
Most important indicator of malignancy in smooth muscle tumors is: 
Select and explain. 
A. Mitotic index, B. Atypia, C. Necrosis, D. Cellularity
A: Mitotic index
Answer: A: Mitotic index 
Explanation: Ans. (a) Mitotic index(Ref: Robbins 9th/pg 1223)Indicator of malignancy in soft tissue tumors (Leiomyosarcoma): Mitotic index Q > Atypia > Necrosis.