Vimentin expression in benign and malignant lesions in the human mammary gland

The distribution pattern of vimentin in mammary gland lesions, including benign lesions (36 cases) and adenocarcinomas (40 cases), was studied with the use of a monoclonal antibody. In myoepithelial cells of mastopathy, the positive vimentin staining was seen in 6 cases (33.3%). Gynecomastia showed strong vimentin expression in myoepithelial cells. Fibroadenomas (14 cases) expressed positive vimentin staining in 8 cases (57.1%) with various staining intensities in myoepithelial cells. Lactating mammary gland tissue was positive for vimentin staining in narrow myoepithelium. In adenocarcinoma, positive reactions in tumor cells were found in 17 cases (41.2%) of solid tubular, 12 cases (33.3%) of papillo-tubular, and 11 cases (54.5%) of scirrhous carcinomas. The staining intensity for vimentin was weak in modified myoepithelial cells and neoplastic cells. Malignant cells in mammary carcinomas with vimentin reactivity usually expressed keratin staining; thus a co-expression of vimentin and keratin was found in mammary carcinomas.