INFLAMMATORY INFILTRATE IN INVASIVE LOBULAR AND DUCTAL CARCINOMA OF THE BREAST

The significance of inflammation in carcinoma of the breast is controv ersial. Little attention has been paid to different patterns of inflam mation or inflammation associated with different histological types of carcinoma. We have looked at the pattern of inflammation in 123 invas ive mammary carcinomas (including 46 lobular), and characterised the i nflammatory cells with immunohistochemistry in 21. We found different patterns of inflammation in ductal and lobular carcinoma. Diffuse infl ammation was seen more in ductal carcinoma, particularly of high grade , and was predominantly composed of macrophages and T cells. It was as sociated with necrosis, but the correlation was weak, suggesting that other factors are important. Perilobular inflammation was seen most fr equently in lobular and high-grade ductal carcinomas, particularly at the tumour edge. Perivascular inflammation was also largely at the tum our edge, but was not more common in any tumour type. In contrast to t he diffuse inflammation, the perivascular and perilobular inflammation was composed of T and B cells. Normal lobules at the tumour edge show ed consistent expression of HLA-DR, whereas lobules away from the tumo ur were negative. A combination of perilobular and perivascular inflam mation composed of B and T cells with epithelial expression of HLA-DR mimicking lymphocytic lobulitis was seen more frequently in lobular th an ductal carcinoma.