A Detailed Histologic Analysis of Flat Epithelial Atypia Diagnosed on Core Biopsy
Brian J Sutton, Kalliopi P Siziopikou, Megan E Sullivan. Northwestern University, Chicago, IL
Background: Flat epithelial atypia (FEA) remains a somewhat controversial diagnosis within breast pathology. The WHO established a definition in 2003, but interpretations and diagnostic thresholds vary between pathologists, and the features described in the literature are numerous and often subjective. In this study, we reviewed breast needle core biopsies (NCB) with FEA as the most significant diagnosis and scored each NCB for 15 different histologic features to determine if 1) different patterns of histologic features become evident and if 2) any specific pattern is more associated with upgrade at excision.
Design: After IRB approval, the pathology database was reviewed for NCB diagnosed as FEA between 1/1/03 and 12/31/10. Patients with atypical ductal hyperplasia (ADH) or cancer were excluded. 85 NCB were reviewed by MS & BS blinded to the excision findings and scored on the following features: dilation of TDLU, intralobular stroma, secretions, calcifications, basophilia, nuclear shape, size & distribution, nucleoli, cytoplasm, mitoses, myoepithelial cell prominence and presence of lobular neoplasia (LN). Relevant patient and excision data was also obtained.
Results: Using Ward's Method, the FEA NCB separated into 3 clusters. Nine histologic criteria were statistically significant in separating the clusters (p<0.0001, see table).
|Feature||Cluster 1 (N=34)||Cluster 2 (N=16)||Cluster 3 (N=35)|
|Expanded interlobular stroma||76%||1%||60%|
|Loss of nuclear polarity||9%||19%||0%|
|Prominent apical snouts||14%||24%||6%|
|Prominent myoepithelial cells||1%||0%||13%|