Immunohistochemical Staining Characteristics of Well Differentiated Invasive Ductal Carcinoma Using the ADH5 Cocktail (CK5/14, P63, and CK7/18): a Potential Interpretative Pitfall

Context In our practice, an antibody cocktail ADH5 (CK5/14, p63, and CK7/18) helps with diagnostic challenges such as identifying microinvasion and foci of invasive carcinoma, differentiating atypical ductal hyperplasia from hyperplasia of the usual type and distinguishing basal phenotypes in triple-negative carcinomas. However, the ADH5 cocktail does have pitfalls and caveats. Objective To describe our experience with the ADH5 cocktail of antibodies in breast pathology. Data sources Institutional knowledge and literature search comprise our data sources. Conclusion The unexpected staining pattern of ADH5 in well-differentiated invasive ductal carcinomas can be challenging to interpret in these lesions with low-grade cytology. This occurrence, when using a multiplex stain, can confuse, and users should be aware of this potential pitfall.