RESUMEN
<p><b>OBJECTIVE</b>To investigate the clinicopathologic features and immunohistochemical of the basal-like subtype of invasive breast carcinoma (BLBC), and to discuss the diagnosis standard.</p><p><b>METHODS</b>Immunohistochemistry was performed in 448 cases of breast carcinoma and these cases were categorized into luminal A, luminal B, null subtypes, HER2-overexpressing and basal-like and their clinicopathologic features were observed under light microscope with stains of HE and immunohistochemical InVitrogen staining.</p><p><b>RESULTS</b>Among the breast cancer patients, the incidence of BLBC was 15.4% (69/448). Morphologic features significantly associated with BLBC constituently included nest structure and showing diffuse growth pattern, large scarring areas without cells in tumor, geographic necrosis, pushing margin of invasion, lymphocytic infiltrate in various degree in tumor stroma, syncytial tumor cell without clear boundaries, tumor cell showing vesicular unclear chromatin and nucleolus, markedly elevated mitotic count, metaplasia (all P < 0.01). Meanwhile, most BLBC showed strong immunoreactivity for CK5/6, CK14, CK17 (all P < 0.01).</p><p><b>CONCLUSION</b>BLBC showed distinct morphologic and immunophenotypic features.</p>