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 d uctal carcinoma in situ (DCIS) have been developed in an effort to pro duce a system which is clinically relevant. In general these systems h ave emphasized the importance of cytological characteristics rather th an architectural patterns. This study attempts to test two of these cl assification systems by comparing the histological grade of the DCIS c omponent, separately assessed according to each system, with the grade of the invasive component in a series of 103 invasive ductal carcinom as. According to the Holland system, the DCIS component was poorly dif ferentiated in 61%, intermediately differentiated in 37%, and well dif ferentiated in 2%. Using the Van Nuys system the DCIS component was cl assified as high grade in 59%, non high grade with necrosis in 10%, an d non high grade without necrosis in 31%. The invasive component was g rade 3 in 48%, grade 2 in 38%, and grade 1 in 14%. The grade of the DC IS component, assessed by each system, was significantly related (P < 0.0001) to the histological grade of the invasive component. Poorly di fferentiated DCIS was mainly associated with grade 3 invasive carcinom a, intermediately differentiated DCIS with all three grades, and well differentiated DCIS with grade 1 invasive carcinoma only. High grade D CIS was primarily associated with grade 3, non high grade with necrosi s with grades 2 and 3, and non high grade without necrosis with grades 1 and 2 invasive carcinoma. There was a strong correlation between th e Holland and Van Nuys systems in the identification of poorly differe ntiated/high grade DCIS lesions. There was less agreement between the two systems in the assessment of lower grade lesions.