Photomicrographs of H&E stains of human breast cancer cell lines and metastatic tumors from mice.

<p>(A) ARM-H (middle, 50×) shows focal residual skeletal muscle (arrow) almost completely replaced and infiltrated by invasive adenocarcinoma (between asterisks); (right, 200×) the same area shows sheets of markedly atypical and pleomorphic carcinoma cells with numerous mitotic figures in a haphazard growth pattern. (B) ARM-G (middle, 50×) lymph node with deposits of metastatic tumor cells within the peripheral sinuses and parenchyma (arrows); (right, 200×) same lymph node with numerous scattered metastatic tumor cells; tumor cells show enlarged nuclei, significant atypia and pleomorphism when compared to the surrounding normal lymphocytes, arrows indicate deposits of tumor cells. (C) ARM-C (middle, 50×) shows sheets of adenocarcnoma cells (between asterisks) invading into adjacent skeletal muscle (arrow); (right, 200×) view of the same area shows markedly pleomorphic and atypical tumor cells with areas of tumor cell necrosis (arrow). (D) ARM-X (middle, 50×) skin (arrow on epidermis), underlying adnexal structures and dermis completely replaced by invasive adenocarcinoma entrapping sweat glands and normal follicles; (right, 200×) the same section showing the markedly atypical tumor cells with mitoses, pleomorphic nuclei, and high nuclear to cytoplasmic ratio invading the dermis and surrounding adnexal structures (triangle); arrow indicates skin adnexal structures.