Collaborative Stage

Note 1: The mitotic count, the number of mitoses per 40 high-power fields (HPF), reflects the potential aggressiveness or prognosis of uveal melanomas. This site-specific factor presumes the denominator of 40 HPF, so just the numerator (the mitotic count) is coded here. For other schemas in which mitotic count is collected, the denominator may vary.
Note 2: An HPF usually has a magnification objective of 40 (a 40x field). As described in the AJCC chapter on uveal melanomas, the typical field area is 0.15-0.19 square millimeters (mm).
Note 3: Record mitotic count to the nearest tenth as documented in the pathology report. For example, a mitotic count of 6/40 HPF would be coded 060.
Note 4: Code the specific mitotic count only per 40 HPF; assume the denominator is 40 HPF if not specified. Use code 996 only if the mitotic count is expressed with a specific denominator other than 40 HPF.

Code	Description
000	0 mitoses per 40 high-power fields (HPF) (40x field) Mitoses absent, no mitoses present, no mitotic activity
001-008	0.1-0.8 mitosis per 40 HPF (40x field)
009	0.9 mitosis per 40 HPF(40x field) Stated as less than 1 mitosis per 40 HPF (40x field)
010-100	1-10 mitoses per 40 HPF (40x field)
110	11 or more mitoses per 40 HPF (40x field)
988	Not applicable: Information not collected for this case (If this information is required by your standard setter, use of code 988 may result in an edit error.)
990	Stated as low mitotic count or rate with no specific number
991	Stated as high mitotic count or rate with no specific number
996	Mitotic count described with denominator other than 40 HPF (40x field)
998	No histologic specimen from primary site
999	Unknown or no information Not documented in patient record

CS Site-Specific Factor 9
Mitotic Count