With regard to the malignant behaviour of leiomyosarcoma, the most impoant criterion is ?

Ans. is 'd' i.e. The number of mitoses per high power field The most impoant diagnostic criterion for distinction between leiomyoma and leiomyosarcoma is the number of mitoses present per high power field. "The most impoant diagnostic criterion is a high rate of mitotic figures (over 10 mitoses per 10 high power fields" - Chandrasoma Taylor Robbins states : 10 or more mitoses per 10 high power fields with or without cellular atypism, indicates malignancy In presence of nuclear atypia or large (epitheloid) cells, 5 mitoses per 10 highpower fields indicates malignancy.