The Bloom Richardson score (see above) can be used to grade the histologic appearance of an infiltrating lobular carcinoma. The histologic grade correlates with tumor size and metastases to lymph nodes.
Issues affecting use of the Bloom-Richardson score in lobular carcinoma:
(1) tubular pattern: Some authors accept the tubular pattern for lobular carcinoma. On the other hand, Tavassoli and others believe the tubular pattern indicates mixed infiltrating ductal and lobular carcinomas. If this view is taken, then all lobular carcinomas must be scored 3 points for the absence of any tubular differentiation.
(2) pleomorphic pattern: This would correlate with Bloom Richardson scores of 8 or 9 (Grade III out of III).
Since tubule formation does not have the same significance in lobular carcinoma as it does for ductal carcinoma it should be possible to make a simpler modification of the Bloom-Richardson score, one including only nuclear pleomorphism and mitotic rate.
Score
Differentiation
2
Grade I
3
Grade I or II
4
Grade II
5
Grade III
6
Grade III
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