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Elston's Modification for the Criteria of Bloom and Richardson in the Histologic Grading of Infiltrating Ductal Carcinoma

Purpose: To histologically grade infiltrating ductal carcinoma using the Bloom and Richardson criteria.

Description

Bloom and Richardson developed a grading scheme for Infiltrating ductal carcinomas based on assessment of certain key histologic features - extent of tubule formation, nuclear pleomorphism and mitotic rate. A score is assigned for each of these measures, and then these are summated to give a total histologic score.


Extent of Tubule Formation

 

Growth Pattern

Score

extensive tubule formation (> 75%)

1

intermediate tubule formation (10-75%)

2

little tubule formation (< 10%)

3

 

Nuclear Pleomorphism

 

Nuclear Features

Score

Nuclei small, regular and uniform

1

Nuclei show moderate variation in size and shape

2

Nuclei show extensive variation in size and shape, with large, abnormal forms

3

 

Mitotic Count

 

The number of mitoses within 10 high-powered fields are counted and a score assigned. The count of the mitotic rate is greatly affected by the field of vision given by the objective. This must be taken into account when applying a score to the number of mitoses counted.

 

Field Diameter in mm

Examples

Mitotic Count Score = 1

Mitotic Count Score = 2

Mitotic Count Score = 3

0.44 mm

Nikon Labophot

0-5 mitoses

6-10 mitoses

> 11 mitoses

0.59 mm

Leitz Ortholux

0-9 mitoses

10-19 mitoses

> 20 mitoses

0.63 mm

Leitz Diaplan

0-11 mitoses

12-22 mitoses

> 23 mitoses

 

If the data in the table is plotted out, the following equations can approximate the break points for separating mitotic count score 1 from 2, and 2 from 3.

 

mitotic count score 1 if mitotic count <= ((122.81 * ((diam in mm)^2)) - (99.8 * (diam in mm) + 25.15)

 

mitotic count score 2 if mitotic count <= ((78.95 * ((diam in mm)^2)) - (21.32 * (diam in mm) + 4.09), and greater than the break point for score 1

 

Scoring

 

histologic score =

= (points for extent of tubule formation) + (points for nuclear pleomorphism)+ (points for mitotic rate)

 

Interpretation

• minimum score is 3

• maximum score is 9.

 

Histologic Score

Grade

Differentiation

3, 4 or 5

I

well-differentiated

6 or 7

II

moderately differentiated

8 or 9

III

poorly differentiated

 


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Specialty

Objective

ICD-10