Immunohistochemistry in the Diagnosis and Classification of Breast Tumors.

Context.—: In the clinical practice of breast pathology, immunohistochemistry (IHC) of different markers is widely used for the diagnosis and classification of breast lesions.

Objective.—: To provide an overview of currently used and recently identified IHC stains that have been implemented in the field of diagnostic breast pathology.

Data sources.—: Data were obtained from literature review and clinical experience of the authors as breast pathologists.

Conclusions.—: In the current review, we summarize the common uses of IHC stains for diagnosing different types of breast lesions, especially invasive and noninvasive breast lesions, and benign and malignant spindle cell lesions. In addition, the cutting-edge knowledge of diagnostic carcinoma markers will lead us to further understand the different types of breast carcinoma and differentiate breast carcinomas from other carcinomas of similar morphology. Knowing the strengths and limitations of these markers is essential to the clinical practice of breast pathology.