Lobular neoplasia on core-needle biopsy--clinical significance.

Background: Approximately 25% of all cases of atypical ductal hyperplasia (ADH) diagnosed on core biopsy of the breast are associated with ductal carcinoma in situ (DCIS) or invasive malignancy at the same site. As a result, surgical excision has become the standard of care for patients with ADH. In contrast, because data on the relation between breast malignancy and lobular neoplasia (LN) detected on core biopsy are limited, clinical management of patients with LN remains controversial. The goal of the current study was to determine the incidence of breast carcinoma at sites of core biopsy exhibiting LN compared with sites of core biopsy exhibiting ADH.

Methods: The results of 2053 core biopsies were reviewed to identify cases of LN and cases of ADH. Follow-up findings on excisional biopsy were categorized as malignancy (DCIS or invasive malignancy) or no malignancy and were compared between the LN group and the ADH group. Mammograms and medical records were reviewed for patients with atypical findings on core biopsy.

Results: One hundred six (5.2%) of 2053 biopsy samples exhibited atypia on core biopsy. Among these 106 samples, ADH was found in 49 (46%), LN was found in 45 (42%), and both ADH and LN were found in 12 (12%). Malignant disease was detected on follow-up excisional biopsy in 22% of patients with ADH (9 of 41), 14% of patients with LN (3 of 21), and 33% of patients with both ADH and LN (4 of 12) on core biopsy. In the LN group, two cases of malignant disease were associated with lobular carcinoma in situ, and the third case was associated with atypical lobular hyperplasia. Mammographic and clinical features were unable to distinguish patients with malignant findings on excisional biopsy from patients without malignant findings.

Conclusions: Malignant disease was found in a substantial percentage of excisional biopsy samples (14%) following the detection of LN on core biopsy. Thus, like patients with ADH, patients with LN on core biopsy could be considered candidates for surgical excision, which would allow full assessment of breast carcinoma risk and thereby facilitate the planning of prevention strategies.