This chapter is intended to provide practical instruction in further assessing core biopsy material in occasionally encountered but important diagnostic scenarios. Further evaluating cases with inherent pitfalls including those with seemingly nondiagnostic findings, instances of excluding concomitant microinvasive carcinoma, and recognizing tangential sections that mimic atypical epithelial proliferations will be discussed. Attention will also be drawn to examples of core biopsies containing multiple diagnoses as well as the use of multiplex immunohistochemistry in these specimens.