Endometrial biopsy is amongst the most frequent specimens evaluated by pathologists. But difficulties in interpretation of findings and the presence of common morphologic mimics, including metaplastic and reactive changes, may lead to misdiagnosis, with important consequences for patient management. In this CAPcast, Dr. Ricardo Lastra discusses the common pitfalls in diagnosis as well as classification of endometrial precursor lesions and neoplasia, as well as the rare diagnoses that may be present in endometrial biopsy specimens. Dr. Lastra will be teaching a CAP19 course on this topic with Dr. Mamta Gupta on Monday, Sept. 21 in Orlando, Florida.