Pure flat epithelial atypia is uncommon in subsequent breast excisions for atypical epithelial proliferation

Abstract

The management of atypical intraductal lesions of the breast remains controversial. In the present study, the subsequent surgical excision results and follow-up data on 86 (3.65%) atypical intraductal lesions and 78 (3.31%) low-grade ductal carcinoma in situ (DCIS) from a cohort of 2358 needle biopsies were examined. There were 17 cases (0.72%) of pure flat epithelial atypia (FEA), 44 (1.87%) pure atypical ductal hyperplasia (ADH), three (0.13%) pure atypical lobular hyperplasia (ALH), 18 (0.76%) combined ADH + FEA, three (0.13%) combined ALH + FEA and one (0.04%) combined ALH + FEA + ADH. Subsequent surgical excisions were done in 53 cases and revealed the following incidences of malignancy: pure FEA (1/8); pure ADH (17/31); FEA + ADH (7/10); FEA + ALH (2/3); and FEA + ALH + ADH (0/1), with pure FEA showing significantly lower incidence of malignancy. In this cohort, there were 703 carcinomas including 155 DCIS with 78 cases (50.3%) being low-grade. FEA with ADH (and/or ALH) was present in 22 (28.2%) of these 78 cases of low-grade DCISs at surgical excisions. Pure FEA was not detected in any of the subsequently excised surgical materials of the atypical intraductal lesions nor the low-grade DCISs. Thus, pure FEA was very unusual in surgical specimens. When pure FEA is detected at needle biopsy, a wait and see approach can be adopted. However, when the FEA is associated with other concomitant atypical intraductal lesions, especially ADH, further excision should be contemplated.

Analysis of Clinical and Pathologic Factors of Pure, Flat Epithelial Atypia on Core Needle Biopsy to Aid in the Decision of Excision or Observation

“…In studies using a 14-gauge CNB, UE rates are between 14-21% with an average number of 5 samples or 200mg of tissue 10 , 17 . In studies with 11-gauge CNB, UE rates are between 0-20% 7 , 9 , 12 , 19 - 20 . In this study, 74% of CNBs of pure FEA were performed with 8-gauge core needles, and the mean number of CNBs was 6 (approximately 600mg of tissue).…”

“…The difference between these two rates, the 17% incidence of pure FEA with cancer at surgical specimen and 0.72-12.2% pure FEA on CNB and associated cancer on surgical excision, is likely the true UE rate. In the current literature, if the FEA on CNB is used to predict excisional biopsy results, UE rates regardless of CNB gauge are between 0-29% 7 - 12 , 15 - 19 . In studies using a 14-gauge CNB, UE rates are between 14-21% with an average number of 5 samples or 200mg of tissue 10 , 17 .…”

Clinicopathological significance of ‘atypical ductal proliferation’ in core needle biopsy of the breast

“…In Japan, atypical ductal proliferation has been histopathologically diagnosed when pathologists had difficulty with interpreting the features at CNB . Results of our present study, however, demonstrated that decreased myoepithelial cell components, identified by p63 immunohistochemistry should be incorporated when designing the clinical algorithm of performing the subsequent biopsy, or not in conjunction with the US finding.…”

“…The term ‘atypical ductal proliferation’ has been also used for these lesions above, due to various factors including the amounts of the specimens available, artifactual changes and others . ‘Atypical ductal proliferation’ is characterized by the presence of atypical cytological or architectural features but is difficult to categorize into any of the histopathological diagnostic entities above . For instance, the widely accepted format of reporting histopathologic results of CNB proposed by The Japanese Breast Cancer Society is composed of assessment categories such as benign or malignant and estimated histological types .…”