Topic 3

Morphological study of inflammatory breast cancer

IBC has a distinct growth pattern compared to non-IBC. In an extensive fraction of the breast, areas of infiltrating carcinoma are separated by large skip areas of normal, tumor-free tissue. In the infiltrating carcinoma components numerous and large intravascular tumor emboli are present. An in-situ component is absent or limited. In the overlying dermis vascular tumor emboli are often observed and co-localize with small areas of infiltrating carcinoma. Given the peculiar observation in the Mary-X animal model of IBC in which primary tumors and their metastases are almost entirely composed of the intravascular component, the growth pattern of IBC in patients migth indicate that the intravascular component of IBC is responsible for the fast local growth of IBC: involvement of the breast with subsequent inflammatory signs typically occurs within weeks. An analogous situation is the extensive intraductal carcinoma, a tumor than can attain a relatively large size with or without small infiltrating areas throughout the tumor.

The aim of this study is to find morphological support in tumor samples of patients with IBC for the above stated hypothesis. A strategy migth be to document the co-localization of emboli and infiltrating areas and to look for characteristics of in-situ carcinoma in the emboli. Desmoplastic reaction surrounding intravascular emboli not accompanied by infiltrating carcinoma would be another argument in favor of the hypothesis.