In situ and invasive lobular neoplasia of the breast

Lobular neoplasia of the breast represents a group of related malignancies with clinical implications ranging from risk lesions [atypical lobular hyperplasia and lobular carcinoma in situ (LCIS)] through to aggressive invasive lesions, notably invasive pleomorphic lobular carcinoma. The diversity in lobular carcinoma is evident at the morphological level, at the molecular marker level and in cytogenetic profiles. Research in these areas is already changing the face of the disease group, for example suggesting that some lobular and ductal carcinomas are closely related and even that one of the lobular group, the tubulo-lobular carcinomas, should, in fact, be regarded as a ductal cancer. More research is required to understand the long-term pathogenic implications of a diagnosis of in situ lobular neoplasia, particularly pleomorphic LCIS , and to understand the genetics behind the well-recognized high risk of bilateral disease. For invasive carcinoma, molecular studies will allow refinement of therapy and the possibility of novel targeted therapies, for example directed against fibroblast growth factor receptor 1.     

Screen‐detected pleomorphic lobular carcinoma in situ (PLCIS): risk of concurrent invasive malignancy following a core biopsy diagnosis

Carder PJ, Shaaban A, Alizadeh Y, Kumarasuwamy V, Liston JC & Sharma N
(2010) Histopathology 57, 472–478
Screen‐detected pleomorphic lobular carcinoma in situ (PLCIS): risk of concurrent invasive malignancy following a core biopsy diagnosis Aims: Pleomorphic lobular carcinoma in situ (PLCIS) is an uncommon, recently recognized variant of lobular carcinoma in situ (LCIS). Its natural history, biological behaviour and clinical characteristics are uncertain. The aim was to review the radiological and pathological findings in a series of screen‐detected PLCIS diagnosed on needle core biopsy with a view to determining the diagnostic features, immunohistological profile and risk of concurrent invasive malignancy. Methods and results: Ten cases of core biopsy‐diagnosed, screen‐detected PLCIS were identified. Core biopsy findings were compared with pathological findings at subsequent surgery. Two cases were associated with possible microinvasion on the core. Two of 10 had invasive lobular carcinoma and one had microinvasive lobular carcinoma on subsequent surgical excision (positive predictive value for malignancy = 30%). There was associated conventional LCIS on either core or excision biopsy in all cases except one. All three cases of oestrogen receptor (ER)‐negative PLCIS arose in the context of ER+ conventional LCIS. Conclusions: PLCIS is a potentially more aggressive lesion than conventional LCIS and may present as mammographic calcification through a breast screening programme. Diagnosis may be problematic and immunohistochemical markers including ER may prove a useful diagnostic adjunct. There is a significant risk of concurrent invasive carcinoma following a core biopsy diagnosis.     

Pleomorphic lobular carcinoma in situ

Lobular carcinoma in situ (LCIS) is often identified as incidental finding in breast biopsies. Pleomorphic LCIS can be associated with invasive lobular carcinoma and also occurs as an isolated lesion presenting with mammographic calcification. Histologically PLCIS may mimic DCIS but the diagnosis is facilitated by greater awareness and the use of immunohistochemistry particularly e-cadherin. It comprises large dyscohesive cells which may be associated with comedo necrosis and calcification. Apocrine and signet ring morphology can be prominent. PLCIS usually arises in a background of classical LCIS; however, the morphological and molecular features suggest that it is biologically a more aggressive disease. The lesion is associated with a significant risk of invasive carcinoma, particularly of lobular type. In its pure form, PLCIS on core biopsy is coded and managed as for DCIS.     

Lobular neoplasia in breast core needle biopsy specimens is not associated with an increased risk of ductal carcinoma in situ or invasive carcinoma

Recent reports suggest that the finding of lobular neoplasia (atypical lobular hyperplasia [ALH] or bular carcinoma in situ [LCIS]) in breast core needle biopsy specimens may be associated with an increased risk of both ductal carcinoma in situ (DCIS) or invasive carcinoma at excision. We reviewed our breast core biopsy material to see if we could confirm this finding. from 4,297 biopsies, 71 cases of lobular neoplasia lone and 35 cases of lobular neoplasia associated with typical ductal hyperplasia were identified. Biopsy follow-up revealed DCIS or invasive carcinoma in none of 6 cases of ALH, none of 9 cases of LCIS, and DCIS in 1 of 11 cases with both atypical ductal hyperplasia and LCIS. Our results suggest that patients with lobular eoplasia in breast core biopsy specimens are not at increased risk of either DCIS or invasive carcinoma at excision, and patients with this finding and no other linical or pathologic indications for biopsy can be llowed up rather than routinely undergo excision.     

In situ lobular proliferations of the breast

Lobular proliferations of the breast include a number of lesions with varying cytological and histological features and clinical significance. Here, we provide an update on the current state of knowledge of classical lobular neoplasia (atypical lobular hyperplasia and lobular carcinoma in situ) and variants (pleomorphic and LCIS with necrosis) with emphasis on the morphological features, histological mimics, molecular profile and clinical relevance. The management of those lesions on both core biopsy and surgical specimens is also discussed.     

Pathologic findings of follow-up surgical excision for lobular neoplasia on breast core biopsy performed for calcification

This study aimed to ascertain pathologic findings of surgical follow-up excision (FUE) on patients who had radiologic finding of calcifications and lobular neoplasia (LN) on core biopsy. Breast core biopsy specimens from 2006-2011 with a diagnosis of pure classic-type LN (lobular carcinoma in situ [LCIS] and atypical lobular hyperplasia [ALH]) with no history of invasive carcinoma (IC) or ductal carcinoma in situ (DCIS) were studied. Two hundred thirty-seven patients with the diagnosis of calcium on radiologic studies had FUE and were included in the study. Cases were divided into group 1 (pure ALH, n = 163) and group 2 (pure LCIS, n = 74). The interval between the core biopsy and FUE ranged from 0.2 to 7 months (mean, 1.5 ± 1.1 months). The risk of upstaging on FUE (DCIS or IC) is as follows: LCIS, 8.1% (6/74) and ALH, 3.1% (5/163). The data indicate that there is a low risk of upstaging to DCIS/IC from a core biopsy diagnosis of lobular neoplasia.     

The diagnosis and management of lobular carcinoma in situ

Lobular carcinoma in situ (LCIS) is a non-invasive proliferation of discohesive cells arising in the terminal duct lobular unit. LCIS was initially described as a marker of bilateral increased risk of invasive breast carcinoma, however more recently it is recognized to act as a non-obligate precursor of invasive lobular carcinoma. There are 3 main types of LCIS; classical LCIS, florid LCIS and pleomorphic LCIS. The morphological characteristics of the 3 subtypes are described, along with differences in tumour biology. LCIS is associated with loss of expression of E-cadherin protein, part of the cadherin:catenin cell adhesion complex. Immunohistochemistry for E-cadherin can assist in the diagnosis of LCIS, but important caveats apply in its interpretation and other markers such as beta catenin and p120 may also be of use. Classical LCIS has a low upgrade rate and recommended management is regular follow up, however pleomorphic and florid LCIS have a higher risk of associated invasive cancer and are managed like DCIS with therapeutic excision aiming for clear margins.     

Fine-needle aspiration cytology of lobular carcinoma in situ

Fine-needle aspiration cytology (FNAC) plays a key role in the preoperative diagnosis of breast carcinoma but is less reliable in the diagnosis of in situ lesions. The objective of the present study was to investigate the cytological features of lobular carcinoma in situ (LCIS), regarding which little data is available to date. Cytological features of FNAC of the breast from 21 patients with histology-proven LCIS were described and compared with surgical specimens. Aspirates from 8/21 cases had cell groups diagnostic for or compatible with LCIS. Aspirates from an additional two cases demonstrated hypercellular, dissociated, and more pleomorphic tumor cells, which were originally diagnosed as invasive lobular carcinoma (ILC). The remaining 11 aspirates were diagnosed as benign or nondiagnostic. FNAC from the eight diagnostic specimens were characterized by loosely cohesive cell groups composed of uniform cells with occasional intracytoplasmic lumina, slightly irregular and eccentric nuclei. We conclude that the main difficulty in diagnosing LCIS by FNAC is sampling rather than recognition of the lesions. However, one should be aware of the cytological features of LCIS in order to reach a correct diagnosis. There are no reliable cytological criteria that help in differentiating pleomorphic and dissociated LCIS from ILC.     

Array-based comparative genomic hybridization of ductal carcinoma in situ and synchronous invasive lobular cancer

It has been increasingly recognized that ductal carcinoma in situ (DCIS), lobular carcinoma in situ (LCIS) and invasive cancer of the breast are often closely associated with one another. However, the genomic relationship between these histologically distinct entities has not been well characterized. Refinements in high-resolution comparative genomic hybridization (CGH) techniques allow for a detailed comparison of genomic alterations in synchronously occurring tumors. The following case illustrates how array CGH may be used to better understand whether synchronous neoplasms share a common origin.     

Fine needle aspiration cytology of lobular carcinoma in situ on ThinPrep

Lobular carcinoma in situ (LCIS) of the breast is a recognized marker for increased risk of invasive carcinoma and has well-established histologic criteria. However, its detection and diagnosis on FNA of breast has not been well defined. Cytology slides (all ThinPrep) of 11 cases with biopsy-proven LCIS at Beth Israel Deaconess Medical Center were reviewed. All 11 cases showed tight and/or loosely cohesive clusters of crowded mildly enlarged nuclei and ten of 11 showed at least moderate cellularity. Single epithelial cells, small but prominent nucleoli, intracytoplasmic lumina, and two distinct epithelial-cell populations were also noted in some cases. As none of these features is specific for LCIS, it would be prudent to report such lesions as atypical so that a core biopsy or excisional biopsy will be performed before definitive treatment. The original FNA diagnosis of the 11 cases ranged from epithelial proliferation without atypia to carcinoma. Three of the 11 cases had fibroadenomas on histology with extensive involvement by LCIS. Since management for LCIS is different from that for invasive carcinoma or DCIS, it should be considered and distinguished from the latter two in cases suspicious for carcinoma on FNA.     

Pleomorphic lobular carcinoma in situ of the breast composed almost entirely of signet ring cells

Some examples of lobular carcinoma in situ (LCIS) may be composed in part of signet ring cells. Such proliferations have been considered examples of pleomorphic LCIS based on pathological features of the more conventional component. However, the occurrence of LCIS composed entirely of signet ring cells is extraordinarily rare. This report describes an example of an in situ proliferation that was composed almost entirely (>95%) of signet ring cells, which was unassociated with an invasive carcinoma and which showed comedo-type necrosis. There was only focal lobulocentric distention by lesional cells, as is typical of classic LCIS. However, discrete, ductal-type cross-sectional profiles showed a purely intraepithelial proliferation of remarkably discohesive signet ring cells. The signet ring cells had intermediate-grade nuclear atypia, no significant mitotic activity and were positive for mucicarmine and PAS stains (the latter with and without diastase predigestion). The cells displayed marked immunoreactivity for high-molecular-weight keratin (stained by 34beta E12 antibody), MUC1, gross cystic disease fluid protein-15, cytokeratin 7 and were negative for cytokeratin 20, E-cadherin, progesterone receptor and HER2/neu. It is concluded that this is an example of a purely signet ring variant of pleomorphic LCIS.     

Atypical ductal hyperplasia and atypia of uncertain significance in core biopsies from mammographically detected lesions: correlation with excision diagnosis

AIMS: To assess: (1) the prevalence of reporting of atypical ductal hyperplasia (ADH) and intraductal atypia of uncertain significance (AUS) in a series of core biopsies from mammographically detected lesions, (2) the proportion of cases where excision revealed breast carcinoma, and (3) whether any diagnoses should be revised on review. METHODS: Breast core biopsy reports from the Sir Charles Gairdner Hospital Breast Assessment Centre for the years 1999-2000 were retrieved. Slides from cases reported as ADH or AUS were reviewed as well as slides from the excision biopsies. RESULTS: There were 1048 core biopsies from 911 women. Breast carcinoma was diagnosed in 197 samples (18.8%) including 88 with invasive carcinoma (8.4%), 109 with ductal carcinoma in situ (DCIS) (10.4%). Three biopsies (0.3%) 'suspicious' of invasive carcinoma proved to be so. Of 52 samples (5.0%) with a diagnosis of ADH or AUS, 46 were excised, showing seven invasive carcinomas, 15 DCIS, 11 ADH, two lobular carcinoma in situ (LCIS), nine fibrocystic change (FCC), one mucocoele-like lesion and one fibroadenoma. The 22 malignancies represented 47.8% of the excised lesions. On review, seven of the 52 original core diagnoses were downgraded to benign hyperplasia. Five underwent excision, revealing two FCC, one complex sclerosing lesion, and two incidental lesions unrelated to the mammographic abnormality, including a microscopic tubular carcinoma and a focus of LCIS. In one case reviewed as unsatisfactory, excision showed invasive carcinoma. Lesions of particular interest included a case of high-grade DCIS with local regression in the core biopsy (so-called 'bumt out DCIS'), and one case diagnosed on excision as micropapillary ADH, where the review diagnosis was micropapillary DCIS. CONCLUSIONS: ADH and AUS were reported in 5.0% of biopsies. There was a high rate of carcinoma (47.8%) in subsequent excisions. Very few diagnoses were revised on review. Current protocols for excision of lesions with a 14-gauge core biopsy diagnosis of ADH/AUS appear justified. Literature review suggests that vacuum-assisted core sampling with 11-gauge needles will not remove the need for excision. Further study of local regression of DCIS and micropapillary lesions will be worthwhile.     

Lobular neoplasia diagnosed on breast Core biopsy: frequency of carcinoma on excision and implications for management

The appropriate follow-up and treatment for patients with a core biopsy diagnosis of lobular neoplasia (atypical lobular hyperplasia or lobular carcinoma in situ) remains controversial. Several studies have attempted to address this issue, with recommendations ranging from close clinical follow-up or surveillance to mandatory surgical excision in all cases. We report the findings at our institution, where virtually every core needle biopsy diagnosis of lobular neoplasia results in follow-up excision. The goal of the study was to identify potential predictors of upgrade to a more significant lesion. We identified 76 patients over a 15-year period with a core biopsy diagnosis of pure lobular neoplasia and no other high-risk lesions. Subsequent surgical excision identified 10 cases (13%) that were upgraded to carcinoma. Upgrade diagnoses included invasive ductal carcinoma (n = 1), invasive lobular carcinoma (n = 4), ductal carcinoma in situ (n = 3), and pleomorphic lobular carcinoma in situ (n = 2). All 10 upgraded cases had imaging findings suspicious for malignancy including irregular masses, asymmetric densities, or pleomorphic calcifications. Of the 10 upgraded cases, 7 were diagnosed as lobular carcinoma in situ on core biopsy. The data support a role for radiologic-pathologic correlation in the evaluation of suspicious breast lesions and suggest that the extent of lobular neoplasia in core biopsy specimens may be an indicator of the likelihood of upgrade to carcinoma.     

The impact of large sections on the study of in situ and invasive duct carcinoma of the breast

Large histologic sections (LHSs) are increasingly used in the study of normal and neoplastic breast tissue. LHSs allow the direct visualization of a large part of the breast glandular tree. Accordingly, LHSs have shown that in situ and invasive lobular carcinoma is a multilobar (and hence multifocal) neoplastic lesion in more than 50% of the cases, and that poorly differentiated duct carcinoma in situ (DCIS grade 3) is frequently unifocal, whereas it is often multifocal when the in situ lesion is a well-differentiated type (DCIS grade 1). Forty-five mastectomies were studied with large sections. Mastectomies were performed when quadrantectomy did not guarantee radical excision of the tumor with adequate cosmesis because of the large size of the lesion or because the neoplastic lesion was located below the nipple. Excluded were cases of lobular neoplasia or invasive lobular carcinoma, because they were reported separately, and cases of mastectomies performed for sarcoma or recurrent phyllodes tumor. All cases had undergone a preoperative diagnostic procedure (fine needle aspiration), and the relative positive material was reviewed. All 45 cases showed in situ duct carcinoma and 37 showed evidence of invasive duct carcinoma. Forty-two cases of DCIS were multifocal, whereas only 4 invasive duct carcinoma were shown as multifocal. When DCIS lesions were subdivided into 3 grades, no statistical significance was seen among the 3 groups of DCIS in regard to multifocality. Nevertheless, DCIS grade 1 was a widespread condition involving more than one lobe and quadrant, whereas DCIS grades 2 and 3 appeared more localized. DCIS grade 1 was more similar to that previously observed in lobular in situ neoplasia/lobular in situ carcinoma. In 66.6% of the cases, DCIS foci were found within the invasive areas, indicating a more than fortuitous occurrence (2-sided P=.0357).     

Mammographically detected in situ lobular carcinomas of the breast

We present ten cases of mammographically detected lobular carcinoma in situ (LCIS), involving a single area of variable size (up to a quadrant) in seven cases and the entire gland in three cases. Histologically, calcifications were associated with necrotic central areas within the in situ carcinomatous foci. Multiple foci of LCIS were observed in all five cases in which mastectomy had been performed. Cytologically, the lesions were characterized by a solid proliferation of round noncohesive cells with nuclei of intermediate size. Immunocytochemically, all cases were E-cadherin and p53 negative, and c-ErbB-2, GCDFP-15 and estrogen receptor positive. The proliferation index, evaluated with Ki67, was in the low range. Four cases were associated with foci of infiltrating lobular carcinoma (ILC). These findings contradict the commonly held opinion that LCIS is not mammographically detectable because of its lack of necrosis and calcification. This study documents the existence of a variant of LCIS exhibiting the mammographic features and central necrosis classically associated with ductal carcinoma in situ (DCIS), while retaining the spatial distribution, cytological composition and immunocytochemical features of lobular carcinoma. Received: 23 July 1999 / Accepted: 22 October 1999     

Lobular carcinoma in situ diagnosed by core needle biopsy: when should it be excised?

Core needle biopsy is the preferred technique for evaluating breast masses and abnormal mammographic findings. The frequency of detection of noninvasive lobular lesions by core needle biopsy is increasing. Historically, the diagnosis of lobular carcinoma in situ has been considered a risk factor for the development of invasive carcinoma, and treatment has consisted of careful clinical follow-up with or without chemopreventive therapeutic agents such as tamoxifen citrate. We retrospectively reviewed core needle biopsy material with the primary diagnoses of lobular carcinoma in situ, atypical lobular hyperplasia, and lobular neoplasia in conjunction with clinical and radiographic findings to make recommendations as to when excision may be merited. We searched our database for core needle biopsy cases with lobular carcinoma in situ, atypical lobular hyperplasia, and lobular neoplasia as the primary diagnosis. Microcalcifications had been sampled with a stereotactically guided, 11 G Mammotome biopsy device, and masses had been sampled with an ultrasound guided, 18 G core needle. Glass slides were reviewed and histological parameters assessed. Mammographic findings were reviewed, and clinical information was obtained from the medical record. When available, excisional biopsy material was reviewed. The 2337 breast core needle biopsies performed from January 1995 to December 2001 included 35 (1.5%) with classic lobular carcinoma in situ (14), lobular neoplasia (4), and atypical lobular hyperplasia (17) as the primary diagnosis. Twelve of these 35 cases (34%) had histological evidence of microcalcifications directly associated with the lobular carcinoma in situ, lobular neoplasia, atypical lobular hyperplasia. Radiologic review revealed 21 calcifications, 6 ultrasonographic masses, and 8 mammographic masses and/or architectural distortions. Excisional biopsy had been performed in 17 cases (49%). In six cases diagnosed as in situ on core needle biopsy, excisional biopsy revealed invasive carcinoma. All of these patients had radiographically detectable masses. Eleven cases had excisional biopsies that showed histology similar to that of the core needle biopsies. The most important predictor of invasive carcinoma on excision was a synchronous mass lesion. Lobular carcinoma in situ involving adenosis and lobular carcinoma in situ with pagetoid spread on core needle biopsies did not show a histologically more aggressive lesion on excision and, therefore, may not require additional surgery. Histologically identified calcifications were associated with lobular lesions 34% of the time; however, their presence inside an in situ lobular lesion did not portend worse pathology on re-excision and should not be a criterion for excision. Based on these findings, we recommend excisional biopsy of lobular carcinoma in situ, atypical lobular hyperplasia or lobular neoplasia only when it is associated with a synchronous mass lesion.     

Tubular carcinoma of the breast and associated intra-epithelial lesions: a comparative study with invasive low-grade ductal carcinomas

Ductal intra-epithelial lesions of the breast are associated with invasive neoplasms and comprise a large spectrum of histological patterns. We have examined 23 cases of pure tubular carcinomas (TCs) of the breast and 53 cases of invasive ductal low-grade carcinomas to determine the relationship and distribution of intra-epithelial lesions, mainly of ductal in situ carcinoma type, but including also lobular intra-epithelial neoplasia (LIN) in both entities. Eleven cases of TC showed flat epithelial atypia (FEA) (47.8%), and, in 14 and 6 cases, micropapillary and cribriform low-grade ductal carcinoma in situ (DCIS) were present (60.7 and 26.1%, respectively). On the opposite, in ductal grade I invasive carcinomas, the most frequent architectural pattern was low-grade DCIS growing in arcades in 26 cases (49%). While absent in TCs, low-grade DCIS of solid type was found in five (9.4%) cases of ductal invasive carcinomas, where FEA were present in seven (13.2%) cases. LIN lesions were present in four (17.4%) cases of TC, whereas they represented 7.5%, as reported by Carstens et al. (Am J Clin Pathol 58:231–238, 1972), of cases of low-grade carcinomas. These results suggest that invasive pure TC and low-grade ductal carcinomas of the breast are different lesions, and support the fact that TC, of low histopathological grade, is a particular distinct tumoural entity.     

PATHOLOGICAL AND BIOLOGICAL CHARACTERISTICS OF INTERVAL BREAST CANCER

INTRODUCTION: Protocols for excision of mammographically detected lesions following core biopsy include all diagnoses of atypical ductal hyperplasia (ADH) or intraductal atypia of uncertain significance (AUS). The aims of this study were to look at: i) the prevalence of reporting ADH and AUS, ii) the proportion of cases where excision revealed breast carcinoma, iii) whether any cases could be downgraded to hyperplasia on review.
METHODS: Breast core biopsy reports from the SCGH Breast Centre for the years 1999–2000 were retrieved. The results of excision biopsy were obtained and slides reviewed.
RESULTS: There were 1048 core biopsies from 911 women. Breast carcinoma was diagnosed in 197 samples (18.8%) including 88 with invasive carcinoma (8.4%), 109 with ductal carcinoma in situ (10.4%) and 3 samples (2.9%) suspicious of invasive carcinoma. The suspicious cases all proved to be invasive carcinomas. There were 53 samples (5.1%) with a diagnosis of ADH or AUS. 46 were excised, showing 7 invasive carcinomas 15 DCIS, 11 ADH, 2 lobular carcinoma in situ (LCIS), 1 mucocoele-like lesion, 1 fibroadenoma and 9 fibrocystic change (FCC). The 22 malignancies represented 47.8% of the excised lesions. At review, 8 of the 53 original diagnoses were downgraded to benign hyperplasia; 5 underwent excision; 2 showed 'incidental' invasive carcinomas, 1 'incidental' LCIS, 1 ADH and 1 FCC.
CONCLUSIONS: There was a low prevalence of reporting of ADH and AUS in core biopsies (5.1%) and a high rate of carcinoma (47.8%) in subsequent excision biopsies. Very few diagnoses of ADH/AUS were downgraded at review. Current protocols for excision of lesions with a core biopsy diagnosis of ADH/AUS appear to be justified.     

Excisional biopsy should be performed if lobular carcinoma in situ is seen on needle core biopsy

CONTEXT: Percutaneous image-guided core biopsy is increasingly becoming the method of choice to evaluate impalpable breast lesions presenting with mammographically detected calcifications or as a mammographically detected mass. Infrequently, a diagnosis of a primary lobular lesion is rendered by needle core biopsy. Although lobular carcinoma in situ (LCIS) and atypical lobular hyperplasia (ALH) are not themselves detectable by mammography, they can be associated with calcifications. The management of patients with a primary diagnosis of LCIS or ALH on needle core biopsy is uncertain. Recommendations include excisional biopsy, tamoxifen citrate therapy, mammographic surveillance, or a combination of these approaches. OBJECTIVE: The purpose of this study was to report the histologic findings of excisional biopsies performed after ALH or LCIS was found in a needle core biopsy. DESIGN: Hematoxylin-eosin-stained slides of 20 needle core biopsy specimens from patients with a primary diagnosis of LCIS or ALH were retrieved from the consultation and surgical pathology files of New York Presbyterian Hospital-Weill Medical College of Cornell University. Histologic diagnoses were confirmed in all cases. RESULTS: Fourteen cases of primary LCIS and 6 cases of ALH found on needle core biopsy were identified. Subsequent excisional biopsy of the 14 LCIS cases revealed the following: LCIS, ductal carcinoma in situ, invasive carcinoma (1 patient; 7%); LCIS, infiltrating lobular carcinoma (1 patient; 7%); LCIS, ductal carcinoma in situ (1 patient; 7%); LCIS (8 patients; 57%); and ALH with or without atypical ductal hyperplasia (3 patients; 21%). Among the 6 patients with ALH on needle core biopsy, 1 had infiltrating lobular carcinoma and LCIS and 2 had LCIS in subsequent excision; other excisions for ALH were benign. Overall, 3 (21%) of 14 patients with a primary diagnosis of LCIS on needle core biopsy had a more significant lesion (ductal carcinoma in situ or invasive carcinoma) in a subsequent excisional biopsy. CONCLUSIONS: Data obtained in this study and in previously published reports lead us to conclude that excisional biopsy may be indicated and should be considered when LCIS is found on needle core biopsy in order to more fully examine the biopsy site for coexistent, clinically inapparent intraductal or invasive carcinoma that may be present in about 25% of these patients. The small number of ALH cases studied produced inconclusive results. We recommend that excisional biopsy be considered if atypical ductal hyperplasia is present with ALH in a needle core biopsy or if the diagnosis of the biopsy specimen is discordant with the mammographic findings.