Less Common Variants and Mimics of DCIS

The purpose of this review is to discuss the less common variants and mimics of ductal carcinoma in situ (DCIS). DCIS lesions are heterogeneous in clinical presentation and behavior, morphology, biomarker profile, and identified genetic aberrations. DCIS is most easily recognized when presenting with classical features. The diagnosis is more challenging when a lesion displays less common cytologic features and has architectural patterns that overlap with other benign or malignant entities.