Collaborative Stage

Note 1: According to CAP, "A mitotic rate of 1 or more mitotic figure per square millimeter is a powerful adverse prognostic factor for cutaneous melanoma."
Note 2: Mitotic rate/count is assessed on all primary tumors and is tabulated as the average number of mitoses per square millimeter. The proportion of cells in a tissue that are undergoing mitosis are expressed as a mitotic index or, roughly, as the number of cells in mitosis in each microscopic high-power field in tissue sections.
Note 3: Record the mitotic rate/count as documented in the pathology report.
Note 4: If there is no documentation or no mention of mitotic rate in the pathology report, code 999.

Code	Description
000	Mitotic rate <1 per square millimeter
001-010	1 - 10 mitoses per square millimeter Code exact measurement Examples: 001 = 1 mitosis per square millimeter 002 = 2 mitosis per square millimeter 010 = 10 mitoses per square millimeter
011	11 mitoses per square millimeter or greater
988	Not applicable: Information not collected for this case
998	No histologic examination of primary site.
999	Unknown Not stated Not documented in patient record

CS Site-Specific Factor 7
Primary Tumor Mitotic Count/Rate