Surgery With regard to the malignant behaviour of leiomyosarcoma, the most impoant criterion is ? A Blood vessel penetration by tumor cells B Tumor cells in lymphatic channels C Lymphocyte infiltration D The number of mitoses per high power field. 💡 Explanation With regard to the malignant behaviour of leiomyosarcoma, the most impoant criterion is ? ✓ Correct Answer: D. The number of mitoses per high power field.