Table 2.

Proposed grading criteria for canine mast cell (MC) neoplasms (9).

	Grade of MC neoplasm*
Variables/criteria**	Low grade*	High grade*
Cell morphology	<3 multinucleated cells /10 HPF	≥3 multinucleated cells /10 HPF
Nulear morphology	<3 bizarre nuclei/10 HPF	≥3 bizarre nuclei/10 HPF
Karyomegaly	<10% of neoplastic cells	≥10% of neoplastic cells
Mitotic figures	<7 MF/10 HPF	≥7 MF/10 HPF

MF, mitotic figures; HPF, high-power fields.

^*Mast cell neoplasms are classified as low grade or high grade based on morphological features and proliferative activity.

^**Each of these criteria indicates a high grade.