As pointed out above, infiltrating lobular carcinoma is classified as (1) classical type, (2) pleomorphic/histiocytoid type, (3) mixed classic and histiocytoid type, and (4) tubulolobular type. Histiocytoid lobular carcinoma seems to behaves more aggressively than classical lobular carcinoma. These two types (and the mixed type) can be seen in lobular carcinoma in situ as well. In the old days, there was no standardized way to grade infiltrating lobular carcinomas. For more than 10 years now, however, most pathologists have adopted the Nottingham histologic score (the same scoring system used for infiltrating ductal carcinomas) in grading infiltrating lobular carcinomas. Three features (tubular differentiation, nuclear atypia and mitotic activity) are graded as scores 1 to 3, and the combined score of all three features decides the overall tumor grade (from grade 1 to 3).

 大部分浸润性小叶癌为1，2级，pleomorphic variant属于3级，是否要分级没有达成共识。