Invasive ductal carcinoma accompanied by ductal carcinoma in situ (DCIS): Comparison of DCIS grade with grade of invasive component

Ln recent years new approaches to the histological classification of ductal carcinoma in situ (DCIS) have been developed in an effort to produce a system which is clinically relevant. In general these systems have emphasized the importance of cytological characteristics rather than architectural patterns. This study attempts to test two of these classification systems by comparing the histological grade of the DCIS component, separately assessed according to each system, with the grade of the invasive component in a series of 103 invasive ductal carcinomas. According to the Holland system, the DCIS component was poorly differentiated in 61%, intermediately differentiated in 37%, and well differentiated in 2%. Using the Van Nuys system the DCIS component was classified as high grade in 59%, non high grade with necrosis in 10%, and non high grade without necrosis in 31%. The invasive component was grade 3 in 48%, grade 2 in 38%, and grade 1 in 14%. The grade of the DCIS component, assessed by each system, was significantly related (P < 0.0001) to the histological grade of the invasive component. Poorly differentiated DCIS was mainly associated with grade 3 invasive carcinoma, intermediately differentiated DCIS with all three grades, and well differentiated DCIS with grade 1 invasive carcinoma only. High grade DCIS was primarily associated with grade 3, non high grade with necrosis with grades 2 and 3, and non high grade without necrosis with grades 1 and 2 invasive carcinoma. There was a strong correlation between the Holland and Van Nuys systems in the identification of poorly differentiated/high grade DCIS lesions. There was less agreement between the two systems in the assessment of lower grade lesions.