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BreastFor Information Only

features should be classified as invasive ductal carcinoma and graded.

^ The diagnostic category of papillary carcinoma should always be qualified as to invasive or noninvasive.

D.Histologic Grade

All invasive breast carcinomas, with the exception of medullary carcinoma (as defined in Note E), should be graded. The grading system used must be specified in the report; the Nottingham combined histologic grade (Elston-Ellis modification of Scarff-Bloom-Richardson grading system) is recommended.4-6 Grading of large core needle biopsies may be done when the quantity of tissue available is sufficient. Within each stage grouping there is a relation between histologic grade and outcome.7

The Nottingham combined histologic grade depends on the extent of tubule formation, the extent of nuclear pleomorphism, and the mitotic count. Each variable is given a score of 1, 2 or 3, and the scores are added to produce a grade. The mitotic score is determined by the number of mitotic figures found in 10 consecutive high power fields (HPFs) in the most mitotically active part of the tumor. Only clearly identifiable mitotic figures (eg, cells in prophase, metaphase, or anaphase) should be counted; hyperchromatic, karyorrhectic, or apoptotic nuclei are excluded. Because of variations in field size, the high power field size must be determined for each microscope and the appropriate point score determined accordingly. Using a micrometer to measure the field diameter of the microscope is recommended.

The following tabulation5 relates to the use of 25x objective with a field diameter of 0.59 mm and a field area of 0.274 mm2.


Tubule formation

Majority of tumor: greater than 75%1

Moderate: 10% to 75%2

Minimal: less than 10%3

Nuclear pleomorphism

Small regular nuclei1

Moderate increase in size, etc2

Marked variation in size, nucleoli, chromatin clumping, etc3

Mitotic count (see also below)

Less than 10 mitoses per 10 HPF1

10 to 20 mitoses per 10 HPF2

Greater than 20 mitoses per 10 HPF3

For a 40x objective with a field diameter of 0.44 mm (area = 0.152 mm2), the equivalent scoring of mitotic activity is as follows.


0 to 5 mitoses per 10 HPF1

6 to 10 mitoses per 10 HPF2

Greater than 10 mitoses per 10 HPF3

The total score is then added and the grade assigned as follows.

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