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.

The authors have declared no competing interest.

This study did not receive any funding

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Feinstein Institutes for Medical Research/Northwell Health system, located in New York City, USA; Ethical: ethical approval is waived; IRB approval number: 21-1334

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