Expression of CD31 by cells of extensive ductal in situ and invasive carcinomas of the breast

CD31, an adhesion molecule expressed by endothelial cells, leukocytes, and platelets, is used in surgical pathology as a marker of normal and neoplast ic vascularization, During the assessment of angiogenesis in breast carcino mas, CD31 expression was observed in a single case of large (5.2 cm diamete r) high nuclear grade ductal carcinoma in situ (HG-DCIS) associated with po orly differentiated invasive ductal carcinoma (G3-IDC), Expression was limi ted to the cell membrane. This study focused on 32 HG-DCIS greater than or equal to 2 cm, either pure or associated with IDC, Cancer cells were CD31() in 11 cases. Double staining using anti-CD31 monoclonal antibody (MAb) an d anti-CD44 MAb, the anti-hyaluronate receptor, showed that foci of CD31(+) and CD44(-) tumour cells could be traced throughout the glandular tree, ma rking the intraductal diffusion of tumour up to Paget's cells at the nipple , The associated G3-IDC and their lymph node metastases were instead CD31and CD44(+). CD31(+) tumours were oestrogen receptor (ER)(-), frequently p5 3(+) and c-erb-B2(+), and infiltrated by CD4(+) T lymphocytes, Normal and h yperplastic epithelia were constantly CD31(-). Other endothelial markers (e ,g, Factor VIII-RA and CD34) were not expressed by carcinoma cells, as was CD38, the CD31 ligand. In conclusion, CD31 expression is a feature acquired by breast cancer cells in the DCIS model. CD31 expression mainly correlate s with tumour cells spreading within the ductal system. Finally, the invasi ve phenotype requires the co-expression of CD31 and CD44. Copyright (C) 200 1 John Wiley & Sons, Ltd.