Intraepidermal cytokeratin 7 immunoreactive cells in the non-neoplastic nipple may represent interepithelial extension of lactiferous duct cells.

AIMS: The interpretation of cytokeratin 7 (CK7)-positive cells in the epidermis of the nipple has been controversial. These cells have been described in Paget's disease of the nipple, and they have also been cited as benign 'Toker' cells or as Merkel cells. Having observed CK7+ cells in histologically unremarkable nipple biopsies, we sought to assess the distribution of CK7+ cells in Paget's disease of the nipple and in histologically unremarkable nipple. METHODS AND RESULTS: Representative sections from 37 cases of Paget's disease of the nipple and 32 cases of histologically unremarkable nipple were obtained. The histologically unremarkable nipple sections were taken from prophylactic mastectomies (n=17) and from autopsies of patients who did not have breast cancer (n=15). CK7 immunostaining was performed on sections from formalin-fixed paraffin blocks. Sequential sections were immunostained with antibodies to low-molecular weight cytokeratin-CAM 5.2 and HER-2/neu. CK7+ cells were present in the epidermis around the opening of the lactiferous ducts in Paget's disease (95%) and in histologically unremarkable nipple (45%) cases. CK7+ cells diminished in number with increasing distance from the orifice of the lactiferous ducts. The lactiferous duct epithelium in Paget's disease and in histologically unremarkable nipple was CK7+ in all specimens when this element was present. CAM5.2 immunostaining had a similar but weaker pattern of reactivity. HER-2/neu reactivity was seen in 68% cases of Paget's disease and was negative in all cases of histologically unremarkable nipple. Tumour cells in two cases of Paget's disease were CK7-. In one of these, the underlying breast carcinoma was also CK7-, the only CK7- tumour in this series. In the other case, the normal lactiferous duct was CK7+ and no underlying carcinomatous tissue was available to study. CONCLUSIONS: The presence of CK7+ cells does not equate to Paget's disease of the nipple. Intraepidermal CK7+ cells in the non-neoplastic nipple can be a manifestation of interepithelial extension of benign lactiferous duct cells. The increased presence of CK7+ cells in Paget's disease probably results either from neoplastic transformation of native intraepithelial lactiferous duct cells or form direct extension/migration of neoplastic cells into the nipple. The distribution of CK7 immunoreactive cells in the nipple epidermis can be helpful in the diagnosis of Paget's disease of the nipple.

Lymphedema in a cohort of breast carcinoma survivors 20 years after diagnosis.

BACKGROUND: To the authors' knowledge, there are no long-term cohort studies of lymphedema, despite the substantial morbidity of arm swelling. The goal of this study was to identify prevalence of breast carcinoma-related lymphedema, time of onset, and associated predictive factors. METHODS: A cohort of 923 women consecutively treated with mastectomy and complete axillary dissection at our center between 1976 and 1978 was observed intensively for 20 years. Two hundred sixty-three study subjects (28.5%) who were alive and recurrence free constituted the cohort for the current study. A subset of 52 women (20% of study population) with contralateral mastectomy was analyzed separately. Subjects reported circumferential arm measurements taken using a validated instrument. In addition to providing analysis of clinical and treatment variables, this study is the first to the authors' knowledge to analyze possible etiologic factors in the posttreatment years, such as occupation, general physical activity, and sports/leisure activities. Univariate and multivariate analytic methods were used. RESULTS: At 20 years after treatment, 49% (128 of 263) reported the sensation of lymphedema. Arm swelling measurements were severe (> or = 2.0 in [5.08 cm]; patients reported measurement in inches) for 13% (33 of 263 women). Seventy-seven percent (98 of 128) noted onset within 3 years after the operation; the remaining percentage developed arm swelling at a rate of almost 1% per year. Of the 15 potential predictive factors analyzed, only 2 were statistically significantly associated with lymphedema: arm infection/injury and weight gain since operation (P < 0.001 and P = 0.02, respectively). CONCLUSIONS: This defined cohort, treated by axillary dissection 20 years ago, documents the high prevalence of lymphedema and its time course. Two significantly associated factors, both potentially controllable, are identified. The current study provides further support for treatments that limit lymph node dissection. The authors are prospectively evaluating patients undergoing sentinel lymph node biopsy.

A potential source of false-positive sentinel nodes: immunostain misadventure.

The clinical and pathologic aspects of sentinel lymph node biopsy have generated much attention. Pitfalls in the pathologic handling of sentinel lymph node specimens have received little attention. We report a case in which a false-positive diagnosis might have been rendered on a sentinel lymph node because of an inadvertent immunostaining error. Attention was drawn to the problem by an unusual pattern of distribution of immunoreactive cells-which proved to be plasma cells rather than metastatic carcinoma cells.

Invasive secretory (juvenile) carcinoma arising in ectopic breast tissue of the axilla.

Mammary carcinoma arising in ectopic breast tissue is an uncommon occurrence. Most reported cases have involved ductal carcinoma, but other types, such as medullary, papillary, and lobular carcinomas, have been described. For pathologists, the diagnosis of mammary carcinoma arising in ectopic breast tissue can be difficult, especially in the axilla, where carcinoma of adnexal origin must be excluded. We describe a 46-year-old woman who developed invasive (juvenile) secretory carcinoma in ectopic right axillary breast tissue and micrometastatic carcinoma in an ipsilateral axillary lymph node. The carcinoma arose in a right axillary mass that had been present for 8 years, from which she had secreted fluid during prior breast-feeding. To our knowledge, this is the first report of secretory carcinoma arising in axillary breast tissue to be documented in the current literature.

Metastatic prostatic adenocarcinoma within a primary solid papillary carcinoma of the male breast.

We report the case of a 78-year-old man who developed a breast mass 12 months after hormonal therapy for palliation of prostatic adenocarcinoma. On histologic and immunohistochemical examination, the breast tumor revealed a unique collision tumor composed of metastatic prostatic adenocarcinoma and solid papillary breast carcinoma.

Pregnancy-like (pseudolactational) hyperplasia: a primary diagnosis in mammographically detected lesions of the breast and its relationship to cystic hypersecretory hyperplasia.

Pregnancy-like (pseudolactational) hyperplasia (PLH) has long been recognized as an incidental finding in breast biopsies performed for various clinically detected benign and malignant conditions. The histologic features of PLH have been well described, including some instances exhibiting cytologic and structural atypia. The presence of calcifications in these lesions was rarely mentioned and was considered to be of little consequence. More recently, however, calcifications in PLH have become the target of needle localization and needle core biopsies. The authors report 12 instances in which PLH was the primary diagnosis in biopsy specimens obtained for radiographic abnormalities, usually calcifications. Six of 12 procedures (50.0%) were performed for mammographically detected calcifications, four cases for a mass, one for an "abnormal mammogram," and one for galactorrhea. Calcifications were present in PLH in 10 biopsies, in benign terminal ducts in one specimen, and were not identified histologically in the remaining specimen. In most instances, calcifications associated with PLH had smooth round or lobulated contours and distinctive, internal, unevenly spaced laminations. Cystic hypersecretory hyperplasia (CHH) was present in five specimens. In four of the five specimens, CHH merged with PLH (PLH/CHH). Four of 12 specimens (33.3%) showed atypia within foci of PLH/CHH. PLH should be recognized as a primary diagnosis in breast biopsies for mammographically detected abnormalities such as calcifications. Some calcifications associated with PLH have a distinctive histologic appearance, and their recognition can aid in the diagnosis of PLH. Additional cases of PLH/CHH must be studied to ascertain the clinical significance, if any, of this previously undescribed entity. The precancerous significance of PLH/CHH and of PLH with atypia has not been determined. In most instances, surgical excision would be prudent if PLH/ CHH or PLH with atypia is present in a needle core biopsy specimen.

Mammary carcinoma with prominent cytoplasmic lipofuscin granules mimicking melanocytic differentiation.

UNLABELLED: We report a case of mammary carcinoma with striking cytoplasmic pigmentation in a 60-year-old Japanese woman who presented with a self-evident nodular lesion in the left breast. METHODS AND RESULTS: After a fine needle aspiration revealing atypical clusters of cells, an excisional biopsy was performed. Histologically, a partially cystic 18 mm lesion containing a 5-mm mural nodule was present. The mural nodule and adjacent thickened epithelium were comprised of atypical cells focally invading into the cyst wall. Striking abundant granular brown pigment resembling melanin was present in some of the neoplastic cells. The differential diagnosis included metastatic melanoma and mammary carcinoma with melanocytic differentiation. After a series of special stains and immunohistochemical studies, the diagnosis of mammary carcinoma with extensive cytoplasmic lipofuscin pigment was rendered. CONCLUSION: Mammary carcinoma with lipofuscin pigment to the degree seen in this case which mimics melanocytic differentiation has not, to our knowledge, previously been documented.

Small cell carcinoma of the breast: a clinicopathologic and immunohistochemical study of nine patients.

Small cell carcinoma of the breast is an uncommon neoplasm that has been reported rarely in the literature. The aim of this study was to characterize better the pathologic and immunohistochemical features of this neoplasm. Nine examples of mammary small cell carcinoma were retrieved from the authors' consultation files and reviewed. The patients ranged in age from 43 to 70 years. Two patients had a previous history of cutaneous malignant melanoma and one had prior lobular carcinoma in situ and atypical duct hyperplasia in the same breast as the small cell carcinoma. Eight patients presented with a mass in the breast; one patient had an axillary tumor. Tumor size ranged from 1.3 to 5.0 cm (mean, 2.6 cm). Histologically, the nine tumors had characteristics of small cell carcinoma with high mitotic activity and necrosis. A dimorphic histologic appearance was observed in four tumors. In one instance, this consisted of small cell carcinoma merging with invasive lobular carcinoma. In three cases, small cell carcinoma was present together with invasive, poorly differentiated duct carcinoma; invasive carcinoma with "lobular and gland-forming elements"; and focal squamous differentiation, respectively. Lymphatic tumor emboli were identified in four instances. An in situ component was seen in seven tumors; five were of the small cell type in ducts and two were of the ductal type with high nuclear grade. Immunohistochemical analysis showed consistent staining for cytokeratin markers but variable staining with neuroendocrine markers. Sixty-six percent of the tumors (six of nine) were reactive for chromogranin, synaptophysin, or peptide hormones, including four positive for chromogranin and synaptophysin, one positive for synaptophysin and calcitonin, and one positive for calcitonin alone. One tumor that was reactive for chromogranin and synaptophysin also contained calcitonin immunoreactive cells, whereas gastrin-releasing peptide was present in two other tumors that were also positive for chromogranin. Leu 7 was positive in three cases that were reactive for either chromogranin or synaptophysin. Five tumors were estrogen and progesterone receptor-positive. All tumors were positive for bcl-2 and negative for HER2/neu. Patients were treated by mastectomy (n = 3) or lumpectomy (n = 6). Eight underwent an axillary dissection that revealed metastatic carcinoma in four patients. Seven patients received adjuvant chemotherapy and four patients received radiation. Two patients also received tamoxifen treatment. Metastases developed in two patients (22%) with a follow-up period of 11 and 32 months. All patients were alive at last follow up 3 to 35 months after treatment. When compared with published reports of mammary small cell carcinoma, our results show that the prognosis in these patients may not be as poor as previously suggested.

In microdissected ductal carcinoma in situ, HER-2/neu amplification, but not p53 mutation, is associated with high nuclear grade and comedo histology.

BACKGROUND: HER-2/neu and p53 are two molecular markers that have been the focus of investigation in patients with invasive breast carcinoma. However, most of the published data have relied on immunohistochemical detection of the proteins as a surrogate marker of the underlying genetic alterations, a detection method that often gives variable results due to technical factors. In addition, there are limited data documenting HER-2/neu amplification and p53 mutations in the various histologic subtypes of ductal carcinoma in situ (DCIS). The authors evaluated a series of microdissected, pure DCIS lesions comprising a spectrum of morphologic subtypes (comedo, micropapillary, papillary, cribriform, and solid) and their corresponding normal breast tissue for genetic aberrations in HER-2/neu and p53. METHODS: HER-2/neu amplification was determined by differential polymerase chain reaction, and p53 mutations were identified by single-strand conformation polymorphism analysis. RESULTS: HER-2/neu amplification was identified in 12 of 30 DCIS samples (40%), and p53 mutations were identified in 6 of 30 DCIS samples (20%). The genetic alterations were not present in any of the normal breast tissue samples. HER-2/neu amplification occurred predominantly in the comedo subtype (69% vs. 18% of the noncomedo subtype; P = 0.008) and in lesions of high nuclear grade (63% vs. 14% of low grade; P = 0.01). There was no difference in the frequency of p53 mutations among the subtypes or between low grade and high grade lesions. No correlation between the presence of the two genetic alterations was observed. CONCLUSIONS: The presence of HER-2/neu amplification, but not p53 mutations, correlates with histologic subtype and nuclear grade. The relatively frequent occurrence of HER-2/neu amplification and p53 mutations in DCIS tissue and their absence in normal breast tissue suggest that these genetic aberrations are important early in breast duct carcinogenesis.

Long term follow-up of women with ductal carcinoma in situ treated with breast-conserving surgery: the effect of age.

BACKGROUND: Although in recent years there has been a dramatic increase in both the incidence of ductal carcinoma in situ (DCIS) and breast-conserving therapy for patients who have this disease, the optimal treatment for these patients remains controversial. Most data regarding outcomes have come from small, retrospective studies, with little data published from prospective, randomized studies. This study investigates the effects of age, postoperative breast irradiation, and other factors on local relapse free survival after breast-conserving surgery for women with DCIS in a large, single-institution series. METHODS: A review was performed of all patients with DCIS who underwent breast-conserving surgery at Memorial Sloan-Kettering Cancer Center from 1978 through 1990. Of the 171 cases identified, data on follow-up and radiation therapy were available for 157. All available pathology slides (132 of 157) were rereviewed to determine histologic subtype, nuclear grade, presence of necrosis, and microscopic tumor size. Sixty-five patients (41%) received postoperative radiation therapy; selection criteria evolved over the time period. The median follow-up was 74 months. RESULTS: Factors that were significantly (P< or =0.05) associated with a lower recurrence rate were older age, noncomedo subtype, lower nuclear grade, negative margins, and postoperative radiation therapy. The 6-year actuarial recurrence rate was 9.6% for patients who received postoperative radiation therapy and 20.7% for patients who had excision only (P = 0.05). Comparison of patients of ages > or =70, 40-69, and <40 years revealed a significantly lower risk of recurrence with increasing age. Actuarial 6-year local relapse rates were 10.8%, 14.0%, and 47.2%, respectively (P = 0.047). A benefit from radiation therapy was suggested for each age group. There was no statistically significant correlation between age group and any histologic factor examined. In multivariate analysis, only margin status was statistically significant (P = 0.05). CONCLUSIONS: In addition to margin status, pathologic factors, and the use of radiation therapy, age is another factor that should be considered in assessing the risk of local recurrence after breast-conserving surgery for patients with DCIS.

Phase II study of weekly intravenous trastuzumab (Herceptin) in patients with HER2/neu-overexpressing metastatic breast cancer.

The HER2/neu proto-oncogene is overexpressed in 25% to 30% of patients with breast cancer. Trastuzumab (Herceptin; Genentech, San Francisco, CA), a recombinant humanized monoclonal antibody with high affinity for the HER2 protein, inhibits the growth of breast cancer cells overexpressing HER2. In this phase II study the efficacy and toxicity of weekly administration of trastuzumab was evaluated in 46 patients with metastatic breast cancer whose tumors overexpressed HER2. A loading dose of 250 mg trastuzumab was administered intravenously, which was followed by 10 weekly doses of 100 mg each. Upon completion of this treatment period, patients with no disease progression could receive a weekly maintenance dose of 100 mg. Patients in this trial had extensive metastatic disease, and most had received prior anticancer therapy. Ninety percent of patients achieved adequate serum levels of trastuzumab. Toxicity was minimal, and no antibodies against trastuzumab could be detected. Objective responses were observed in 5 of the 43 evaluable patients, which included 1 complete remission and 4 partial remissions, for an overall response rate of 11.6%. Responses were seen in mediastinum, lymph nodes, liver, and chest wall lesions. Minor responses (seen in 2 patients) and stable disease (14 patients) lasted for a median of 5.1 months. These results demonstrate that trastuzumab is well tolerated and clinically active in patients with HER2-overexpressing metastatic breast cancers who have received extensive prior therapy. The regression of human cancer through the targeting of putative growth factor receptors such as HER2 warrants further evaluation of trastuzumab in the treatment of breast cancer.

Epidermal growth factor, estrogen, and progesterone receptor expression in primary sweat gland carcinomas and primary and metastatic mammary carcinomas.

The distinction between primary sweat gland carcinomas and metastatic breast carcinoma to the skin is sometimes difficult. In an effort to improve this discrimination, we compared the immunohistochemical staining pattern of 42 primary sweat gland carcinomas (SGCs) with 30 metastases from breast carcinoma (BC) to the skin, 125 primary BCs, and 30 noncutaneous metastases from BCs. The antibodies used were against the receptors for epidermal growth factor (EGF-R), estrogen receptor (ER), and progesterone receptor (PR). The frequencies of positive staining were as follows for EGF-R: 34 (81%) of 42 SGCs, 5 (17%) of 30 BCs metastatic to skin, 28 (22%) of 125 primary BCs, and 6 (20%) of 30 noncutaneous BC metastases. For ER, the frequencies were 9 (21%) of 42 SGCs and 10 (33%) of 30 BCs metastatic to skin. The frequencies for PR were 8 (19%) of 42 SGCs and 8 (27%) of 30 BCs metastatic to skin. These results suggest that expression of EGF-R may be diagnostically helpful, because it is strongly associated with SGCs when compared with metastatic BCs (P < .0001). This association is also present when ductal eccrine and apocrine types of SGC, which are the histologic subtypes of SGC most difficult to distinguish from metastatic BC, are separately analyzed (P < .001). The frequencies of expression of ER and PR in SGCs and BCs metastatic to skin were not significantly different.

Lobular carcinoma in situ at percutaneous breast biopsy: surgical biopsy findings.

OBJECTIVE: The purpose of this study was to review surgical histologic findings in women with lobular carcinoma in situ (LCIS) at percutaneous breast biopsy. MATERIALS AND METHODS: Retrospective review was performed of 1315 consecutive lesions that underwent percutaneous breast biopsy. Percutaneous biopsy yielded LCIS in 16 (1.2%) lesions. Subsequent surgical biopsy was performed in 14 lesions in 13 women. Histologic findings were reviewed. RESULTS: In five of the 14 lesions, percutaneous biopsy yielded LCIS and a high-risk lesion (radial scar in three and atypical ductal hyperplasia in two); in one (20%) of these five lesions, surgery revealed ductal carcinoma in situ (DCIS). In four of the 14 lesions, the LCIS in the percutaneous biopsy had features that overlapped with those of DCIS; in two (50%) of these four lesions, surgery revealed DCIS (n = 1) or infiltrating lobular carcinoma (n = 1). In the remaining five of the 14 lesions, surgery revealed no DCIS or infiltrating carcinoma. Five (38%) of 13 women with LCIS lesions had synchronous or metachronous infiltrating carcinoma (three ductal, one lobular, one mixed) in the ipsilateral (n = 1) or contralateral (n = 4) breast. CONCLUSION: Surgical excision was warranted in lesions in which LCIS was found at percutaneous breast biopsy when the percutaneous biopsy histologic features overlapped with those of DCIS, when a high-risk lesion was present, or when there was imaging-histologic discordance. LCIS without these factors was not shown to require surgical excision in our small series, but a larger study is needed. Diagnosis of LCIS at percutaneous biopsy is a marker for women who are at increased risk of ductal or lobular carcinoma in either breast.

Sentinel lymph node biopsy after percutaneous diagnosis of nonpalpable breast cancer.

PURPOSE: To determine the technical success rate of sentinel lymph node biopsy in women with nonpalpable infiltrating breast cancer diagnosed by using percutaneous core biopsy and to determine the frequency with which sentinel lymph node biopsy obviated axillary dissection. MATERIALS AND METHODS: Retrospective review revealed 33 women who underwent sentinel node biopsy after percutaneous core biopsy diagnosis of nonpalpable infiltrating breast cancer. Sentinel nodes were identified with radioisotope and blue dye; the procedure was technically successful if sentinel nodes were found at surgery. All sentinel nodes were excised. Axillary dissection was performed if tumor was present in sentinel nodes. RESULTS: Sentinel nodes were found at surgery in 30 women (91%). Sentinel nodes were identified with both radioisotope and blue dye in 22 (73%) of these women, with only radioisotope in six (20%), and with only blue dye in two (7%). Sentinel nodes were found in 12 (80%) of 15 women in the first half of the study versus all 18 (100%) women in the second half (P = .08). Sentinel nodes were free of tumor in 23 (77%) of 30 women. In six (86%) of seven women with tumor in sentinel nodes, the sentinel nodes were the only nodes with tumor. CONCLUSION: Sentinel node biopsy was successful in 30 women (91%) with nonpalpable infiltrating carcinoma diagnosed with percutaneous core biopsy and obviated axillary dissection in 23 women (70%). Using both radioisotope and blue dye may increase the success rate. A learning curve exists, and success improves with experience.

Lessons learned from 500 cases of lymphatic mapping for breast cancer.

OBJECTIVE: To evaluate the factors affecting the identification and accuracy of the sentinel node in breast cancer in a single institutional experience. SUMMARY BACKGROUND DATA: Few of the many published feasibility studies of lymphatic mapping for breast cancer have adequate numbers to assess in detail the factors affecting failed and falsely negative mapping procedures. METHODS: Five hundred consecutive sentinel lymph node biopsies were performed using isosulfan blue dye and technetium-labeled sulfur colloid. A planned conventional axillary dissection was performed in 104 cases. RESULTS: Sentinel nodes were identified in 458 of 492 (92%) evaluable cases. The mean number of sentinel nodes removed was 2.1. The sentinel node was successfully identified by blue dye in 80% (393/492), by isotope in 85% (419/492), and by the combination of blue dye and isotope in 93% (458/492) of patients. Success in locating the sentinel node was unrelated to tumor size, type, location, or multicentricity; the presence of lymphovascular invasion; histologic or nuclear grade; or a previous surgical biopsy. The false-negative rate of 10.6% (5/47) was calculated using only those 104 cases where a conventional axillary dissection was planned before surgery. CONCLUSIONS: Sentinel node biopsy in patients with early breast cancer is a safe and effective alternative to routine axillary dissection for patients with negative nodes. Because of a small but definite rate of false-negative results, this procedure is most valuable in patients with a low risk of axillary nodal metastases. Both blue dye and radioisotope should be used to maximize the yield and accuracy of successful localizations.

Epithelial displacement after stereotactic 11-gauge directional vacuum-assisted breast biopsy.

OBJECTIVE: Displaced epithelial fragments at percutaneous biopsy of ductal carcinoma in situ (DCIS) may mimic stromal invasion. This study was undertaken to determine the frequency of epithelial displacement in DCIS lesions of patients who underwent stereotactic 11-gauge directional vacuum-assisted breast biopsy. MATERIALS AND METHODS: We retrospectively reviewed 28 consecutive DCIS lesions in patients who underwent stereotactic 11-gauge directional vacuum-assisted breast biopsy followed by surgery. Surgical specimens were examined for histologic evidence of epithelial displacement, consisting of fragments of epithelium in artifactual spaces in breast parenchyma or in lymphovascular channels, accompanied by hemorrhage, fat necrosis, inflammation, hemosiderin-laden macrophages, or granulation tissue. RESULTS: The median number of specimens obtained per lesion was 14 (range, seven to 45). The median interval from stereotactic biopsy to surgery was 27 days (range, 10-59 days). Surgery revealed DCIS in 19 (68%) of 28 lesions, DCIS and infiltrating carcinoma in four lesions (14%), and no residual carcinoma in five lesions (18%). Reactive changes at the biopsy site were identified in all cases. Displacement of benign epithelium into granulation tissue at the stereotactic biopsy site was identified in two cases (7%). We found no evidence of displacement of malignant epithelium. CONCLUSION: Epithelial displacement is uncommon after stereotactic 11-gauge directional vacuum-assisted biopsy of the breast. We observed displacement of benign epithelium in two (7%) of 28 DCIS lesions and no displacement of malignant epithelium.

Percutaneous large-core biopsy of papillary breast lesions.

OBJECTIVE: This study was undertaken to assess the accuracy of percutaneous large-core biopsy in evaluating papillary breast lesions. MATERIALS AND METHODS: A retrospective review of imaging-guided large-core breast biopsy of 1077 consecutive lesions revealed that papillary lesions were diagnosed in 34 (3%) cases. Surgical correlation (n = 22) or minimum 2 years' mammographic follow-up (n = 4) were available for 26 papillary lesions. Mammographic and histologic findings in these 26 cases were reviewed. RESULTS: Percutaneous biopsy histology had benign findings in nine lesions, atypical in 10, and malignant in seven. Of seven lesions yielding benign papilloma at percutaneous biopsy, none (0%) had carcinoma at surgery or mammographic follow-up. Surgery revealed carcinoma in one of two lesions yielding papillomatosis at percutaneous biopsy. This lesion was a spiculated mass; surgical biopsy, recommended because of mammographic-histologic discordance, revealed a radial sclerosing lesion and ductal carcinoma in situ (DCIS). Of 10 papillary lesions with atypical ductal hyperplasia at percutaneous biopsy, surgery revealed DCIS in three (30%). Of seven lesions in which percutaneous biopsy yielded papillary DCIS, surgery revealed DCIS in all seven; three (43%) also had invasive carcinoma. CONCLUSION: Among our patients, diagnosis by percutaneous core biopsy of benign papillary lesions proved to be accurate when concordant with imaging findings. Surgical excision was indicated when diagnosis by percutaneous biopsy revealed atypical papillary lesions or papillary DCIS. A larger series with longer follow-up is required to assess the clinical course of benign papillary lesions without atypia that are not excised after percutaneous large-core breast biopsy.