Imaging Features Following Breast Explant Surgery: A Pictorial Essay.

Breast implants can be removed with breast explantation surgery (BES) for various reasons, including patient dissatisfaction, capsular contracture, implant infection or rupture, breast implant-associated anaplastic large cell lymphoma, and a recently emerging phenomenon called breast implant illness. There is very limited data on the imaging appearance after BES. A retrospective chart review was performed for patients with BES findings on imaging reports for the period between October 2016 and October 2021. When assessing BES techniques, a key element is determining whether the implant's fibrous capsule requires removal. The second important question is if the patient requires an additional aesthetic procedure after BES. BES techniques include capsulotomy, and partial, total, or en bloc capsulectomy. Adjunctive aesthetic or reconstructive procedures after BES include fat grafting, mastopexy, augmentation, and reconstruction with flaps. The majority of post-BES breast imaging findings are related to the surgical scar/bed, thereby confirming that the type of explantation surgery is important. Imaging findings after BES include focal and global asymmetries, architectural distortions, calcifications, calcified and non-calcified fat necrosis, masses, hematomas, seromas, capsular calcifications, and silicone granulomas. Most importantly, since these patients have residual breast tissue, paying attention to imaging features that are suspicious for breast cancer is necessary.

The Challenging Image-Guided Preoperative Breast Localization: A Modality-Based Approach.

Breast conservation surgery (BCS) is the standard of care for treating patients with early-stage breast cancer and those with locally advanced breast cancer who achieve an excellent response to neoadjuvant chemotherapy. The radiologist is responsible for accurately localizing nonpalpable lesions to facilitate successful BCS. In this article, we present a practical modality-based guide on approaching challenging pre-operative localizations and incorporate examples of challenging localizations performed under sonographic, mammographic, and MRI guidance, as well as under multiple modalities. Aspects of preprocedure planning, modality selection, patient communication, and procedural and positional techniques are highlighted. Clip and device migration is also considered. Further, an overview is provided of the most widely used wire and nonwire localization devices in the United States. Accurate pre-operative localization of breast lesions is essential to achieve successful surgical outcomes. Certain modality-based techniques can be adopted to successfully complete challenging cases.

Bracketing with Multiple Radioactive Seeds to Achieve Negative Margins in Breast Conservation Surgery: Multiple Seeds in Breast Surgery.

INTRODUCTION: Breast conservation surgery (BCS) is the treatment of choice for unifocal, early-stage breast cancer. The ability to offer BCS to a wider subset of patients, including those with multifocal/multicentric cancer as well as extensive ductal carcinoma in situ, has emerged over time, especially in those undergoing joint oncoplastic reconstruction and those treated with neoadjuvant therapy. However, localization techniques using multiple radioactive seeds for bracketing in this patient subset have not been validated. MATERIALS AND METHODS: A single-institution retrospective review was conducted of all patients with breast cancer who underwent BCS, guided by multiple bracketed iodine I 125 radioactive seeds between January 2014 and April 2017. RESULTS: Bracketing of breast cancer using 2 or more radioactive seeds was performed in 157 breasts in 156 patients. Negative margins were achieved in 124 of 157 (79%) breasts, including 33 cases (21%) that underwent targeted margin reexcision at the time of surgery after intraoperative, multidisciplinary margin assessment. Thirty-three cases (21%) resulted in close or positive margins, of which 11 (7%) and 10 (6.4%) underwent completion mastectomy or repeat lumpectomy, respectively. Twelve patients (7.6%) did not undergo reexcision. En bloc resection was successful in 134 of 157 (85.4%) lumpectomies. Eighty-nine percent of the procedures were coupled with oncoplastic reconstruction. CONCLUSION: Bracketing techniques using multiple radioactive seeds expands the indications for breast conservation therapy in patients who would have traditionally required mastectomy. Intraoperative margin assessment improves surgical and pathologic success. Larger defects created by multifocal resection are optimally managed in concert with oncoplastic reconstruction to minimize asymmetries and aesthetic defects.

68Ga-DOTATATE Uptake in Primary Breast Cancer.

ABSTRACT: 68Ga-DOTA peptides have revolutionized the imaging of neuroendocrine tumors because the agents are specific to somatostatin receptors. However, other tumors, including breast cancer, have been shown to express somatostatin receptors. We present the case of a 74-year-old woman with primary cardiac paraganglioma, who was found to have 68Ga-DOTATATE activity in the breast on staging PET/CT. Subsequent breast imaging workup and biopsy confirmed primary invasive lobular breast cancer, which was not 18F-FDG-avid on prior FDG PET/CT. Our case is in alignment with prior studies that suggest that 68Ga-DOTA peptides may play a future role in imaging breast cancer patients.

Oncologic Safety and Surveillance of Autologous Fat Grafting following Breast Conservation Therapy.

BACKGROUND: Autologous fat grafting is a useful adjunct following breast reconstruction. The impact of autologous fat grafting on oncologic safety and surveillance remains questionable, particularly following breast conservation therapy. METHODS: The authors performed a retrospective review of patients who underwent delayed fat grafting following breast conservation therapy between 2006 and 2016. A control group of conservatively managed patients without grafting was matched for cancer stage, age, body mass index, and follow-up. Outcomes included locoregional recurrence and oncologic surveillance. RESULTS: Seventy-two patients were identified per cohort. There were no differences in median age (50 years versus 51 years; p = 0.87), body mass index (28.2 kg/m versus 27.2 kg/m; p = 0.38), or length of follow-up (61.9 months versus 66.8 months; p = 0.144) between controls and grafted patients, respectively. Overall, four patients in each cohort experienced recurrence (5.6 percent; p = 1.00) with similar cumulative incidence estimates observed (log-rank test, p = 0.534). There were no significant differences in palpable mass (9.7 percent versus 19.4 percent; p = 0.1), fat necrosis (34.7 percent versus 33.3 percent; p = 0.86), calcifications (37.5 percent versus 34.7 percent; p = 0.73), or indication for breast biopsy (15.3 percent versus 22.2 percent; p = 0.23) between breast conservation and breast conservation therapy plus autologous fat grafting cohorts, respectively. CONCLUSIONS: Overall, the authors found no difference in recurrence rates after breast conservation with or without delayed fat grafting. Furthermore, there were no differences in the rates of fat necrosis, palpable mass, and abnormal radiographic findings. This study represents the longest follow-up to date in in a large matched study of autologous fat grafting with breast conservation therapy demonstrating oncologic safety and no interference with follow-up surveillance. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Should abbreviated breast MRI be compliant with American College of Radiology requirements for MRI accreditation?

OBJECTIVE: To evaluate non-inferiority and diagnostic performance of an American College of Radiology compliant abbreviated MRI protocol (AB-MRI) compared with standard-of-care breast MRI (SOC-BMRI) in patients with increased breast cancer risk. MATERIAL AND METHODS: Women with increased lifetime breast cancer risk by American Cancer Society guidelines underwent breast MRI at a single institution between October 2015 and February 2018. AB-MRI was acquired at 3.0 T with T2-weighted extended fast spin echo triple-echo Dixon and pre- and post-contrast 3D dual-echo fast spoiled gradient echo two-point Dixon sequences with an 8-channel breast coil 1-7 days after SOC-BMRI. Three readers independently reviewed AB-MRI and assigned BI-RADS categories for maximum intensity projection images (AB1), dynamic contrast-enhanced (DCE) images (AB2), and DCE and non-contrast T2 and fat-only images (AB3). These scores were compared to those from SOC-BMRI. RESULTS: Cancer yield was 14 per 1000 (women-years) in 73 women aged 26-75 years (mean 53.5 years). AB-MRI acquisition times (mean 9.63 min) and table times (mean 15.07 min) were significantly shorter than those of SOC-BMRI (means 19.46 and 36.3 min, respectively) (p < .001). Accuracy, sensitivity, specificity, and positive and negative predictive values were identical for AB3 and SOC-BMRI (93%, 100%, 93%, 16.7%, and 100%, respectively). AB-MRI with AB1 and AB2 had significantly lower specificity (AB1 = 73.6%, AB2 = 77.8%), positive predictive values (AB1 = 5%, AB2 = 5.9%), and accuracy (AB1 = 74%, AB2 = 78%) than those of SOC-BMRI (p = .002 for AB1, p = .01 for AB2). CONCLUSION: AB-MRI was acquired significantly faster than SOC-BMRI and its diagnostic performance was non-inferior. Inclusion of T2 and fat-only images was necessary to achieve non-inferiority by multireader evaluation.

Association of Retrospective Peer Review and Positive Predictive Value of Magnetic Resonance Imaging-Guided Vacuum-Assisted Needle Biopsies of Breast.

OBJECTIVE: To evaluate the association between retrospective peer review of breast magnetic resonance imaging-guided vacuum-assisted needle biopsies and positive predictive value of subsequent magnetic resonance imaging-guided biopsies. MATERIALS AND METHODS: In January, 2015, a weekly conference was initiated in our institution to evaluate all breast magnetic resonance imaging-guided vacuum-assisted needle biopsies performed over January 1, 2014-December 31, 2015. During this weekly conferences, breast dynamic contrast-enhanced magnetic resonance imaging findings of 6 anonymized cases were discussed and then the faculty voted on whether they agree with the biopsy indication, accurate sampling and radiology-pathology correlation. We retrospectively reviewed and compared the magnetic resonance imaging indication, benign or malignant pathology rates, lesion types and the positive predictive value of magnetic resonance imaging-guided vacuum-assisted needle biopsy in the years before and after initiating this group peer review. RESULTS: The number of dynamic contrast-enhanced magnetic resonance imaging and magnetic resonance imaging-guided vacuum-assisted needle biopsies before and after initiating the review were 1447 vs 1596 (p=0.0002), and 253 (17.5%) vs 203 (12.7%) (p=0.04), respectively. There was a significant decrease in the number of benign biopsies in 2015 (n=104) compared to 2014 (n=154, p=0.04). The positive predictive value of magnetic resonance imaging-guided biopsy significantly increased after group review was implemented (Positive predictive value in 2014=%39.1 and positive predictive value in 2015=%48.8) (p=0.03), although the indications (p=0.49), history of breast cancer (p=0.14), biopsied magnetic resonance imaging lesion types (p=0.53) were not different. Less surgical excision was performed on magnetic resonance imaging-guided vacuum-assisted needle biopsy identified high-risk lesions in 2015 (p=0.25). CONCLUSION: Our study showed an association between retrospective peer review of past biopsies and increased positive predictive value of magnetic resonance imaging-guided vacuum-assisted needle biopsies in our institution.

Transection of Radioactive Seeds in Breast Specimens.

Radioactive seed localization is a new procedure for localizing breast lesions that has several advantages over the standard wire-localization procedure. It is reported to be safe for both patients and medical personnel. Although it is theoretically possible to transect the titanium-encapsulated seed while processing the breast specimen in the pathology laboratory, the likelihood of such an event is thought to be exceedingly low. In fact, there are no previous reports of such an event in the literature to date. We recently encountered 2 cases in which a radioactive seed was inadvertently transected while slicing a breast specimen at the grossing bench. In this report, we describe each case and offer recommendations for minimizing radioactive exposure to personnel and for preventing radioactive contamination of laboratory equipment.

Imaging Factors That Influence Surgical Margins After Preoperative 125I Radioactive Seed Localization of Breast Lesions: Comparison With Wire Localization.

OBJECTIVE: The objective of this study was to compare the potential influence of imaging variables on surgical margins after preoperative radioactive seed localization (RSL) and wire localization (WL) techniques. MATERIALS AND METHODS: A total of 565 women with 660 breast lesions underwent RSL or WL between May 16, 2012, and May 30, 2013. Patient age, lesion type (mass, calcifications, mass with associated calcifications, other), lesion size, number of seeds or wires used, surgical margin status (close positive or negative margins), and reexcision and mastectomy rates were recorded. RESULTS: Of 660 lesions, 127 (19%) underwent RSL and 533 (81%) underwent WL preoperatively. Mean lesion size was 1.8 cm in the RSL group and 1.8 cm in the WL group (p = 0.35). No difference in lesion type was identified in the RSL and WL groups (p = 0.63). RSL with a single seed was used in 105 of 127 (83%) RSLs compared with WL with a single wire in 349 of 533 (65%) WLs (p = 0.0003). The number of cases with a close positive margin was similar for RSLs (26/127, 20%) and WLs (104/533, 20%) (p = 0.81). There was no difference between the RSL group and the WL group in close positive margin status (20% each, p = 0.81), reexcision rates (20% vs 16%, respectively; p = 0.36), or mastectomy rates (6% each, p = 0.96). Lesions containing calcifications were more likely to require more than one wire (odds ratio [OR], 4.44; 95% CI, 2.8-7.0) or more than one seed (OR, 7.03; 95% CI, 1.6-30.0) when compared with masses alone (p < 0.0001). Increasing lesion size and the presence of calcifications were significant predictors of positive margins, whereas the use of more than one wire or seed was not (OR, 0.9; 95% CI, 0.5-1.5) (p = 0.75). CONCLUSION: Close positive margin, reexcision, and mastectomy rates remained similar in the WL group and RSL group. The presence of calcifications and increasing lesion size increased the odds of a close positive margin in both the WL and RSL groups, whereas the use of one versus more than one seed or wire did not.

Sonography and Sonographically Guided Needle Biopsy of Internal Mammary Nodes in Staging of Patients With Breast Cancer.

OBJECTIVE: The purpose of this study was to identify the prevalence of occult nodal metastases on routine ultrasound examination of internal mammary (IM) nodal basins in patients with breast cancer. MATERIALS AND METHODS: Patients with primary breast cancer (n = 595) underwent breast ultrasound evaluation between September 1, 2011, and April 1, 2012. For all patients, ultrasound examination included a survey of the axillary, infraclavicular, IM, and supraclavicular nodal basins. Patient demographics, breast cancer histopathologic type, and grade, size, location, and presence of metastatic nodes in regional nodal basins were recorded. Fisher exact test and Wilcoxon rank test were used for statistical analysis. RESULTS: Fifty-eight of 595 (10%) patients had positive IM ultrasound finding, with eight (1.3%) patients having isolated IM involvement. Patients with positive IM ultrasound findings were statistically significantly younger than those without such findings (median age, 42 vs 57 years; p < 0.0001). Of the 58 patients with positive IM ultrasound, 29 (50%) underwent ultrasound-guided needle biopsy, which confirmed malignancy in 26 of 29 (90%) patients. Nonlateral (p < 0.001) grade 3 (p < 0.001) tumors larger than 5 cm (p < 0.0006) with the estrogen receptor-negative HER2/neu-negative subtype (p < 0.001) associated with axillary, infraclavicular, or supraclavicular metastases (p < 0.001) were more likely to be associated with positive IM ultrasound findings. IM ultrasound resulted in an N status change for 46 of 595 (8%) patients and of the overall clinical stage for 38 (6.4%) patients. CONCLUSION: IM ultrasound and ultrasound-guided fine-needle aspiration biopsy are feasible, sensitive, and specific. Application of IM ultrasound and ultrasound-guided needle biopsy in a selected subpopulation of young patients with medial or central estrogen receptor-negative HER2/neu-negative breast cancer may result in a change in clinical stage and modify the treatment plan.

Multimodality Imaging of the Reconstructed Breast.

The purpose of this article is to illustrate the imaging characteristics and pathologic findings associated with various types of breast reconstruction in women who have undergone mastectomy to treat breast cancer. As the use of breast reconstruction becomes more prevalent, it is imperative that radiologists interpreting imaging studies identify normal and abnormal imaging findings associated with differing breast reconstruction techniques, recognize imaging manifestation of expected complications, and reliably distinguish these from malignancy.

Multimodality imaging of triple receptor-negative tumors with mammography, ultrasound, and MRI.

OBJECTIVE: We retrospectively reviewed imaging findings for 44 patients with triple receptor-negative breast carcinomas on mammography, sonography, and MRI to determine the imaging characteristics of triple receptor-negative cancers that may improve diagnosis at the time of presentation. CONCLUSION: Despite their large size at presentation, triple receptor-negative cancers may be occult on mammography or sonography and frequently have benign or indeterminate features. MRI identified all triple receptor-negative cancers and showed features that had a high positive predictive value for malignancy.

Mammary angiosarcomas: imaging findings in 24 patients.

PURPOSE: To retrospectively evaluate the clinical, imaging, and pathologic findings of mammary angiosarcomas in 24 patients. MATERIALS AND METHODS: The institutional review board approved this HIPAA-compliant study and waived informed consent. Twenty-four patients with records in the surgical pathology database who had a diagnosis of mammary angiosarcoma (n = 26) and who underwent preoperative imaging with mammography, ultrasonography (US), or magnetic resonance (MR) imaging were included. Mean and median ages at time of diagnosis were 40 and 38 years, respectively (range, 15-77 years). Images were reviewed in consensus by two radiologists with the American College of Radiology Breast Imaging Reporting and Data System lexicon and were compared with pathologic findings. Total length of follow-up (in months) was determined by the interval from the time of diagnosis to the time of last follow-up. Information on overall and disease-free survival was also obtained. RESULTS: Mean tumor size at time of diagnosis was 5.9 cm (range, 1-12 cm). Nineteen tumors manifested as a palpable mass, four manifested with progressive breast swelling, and three were asymptomatic. Mammograms of 16 tumors showed a noncalcified mass in eight, focal asymmetry in five, and no abnormality in three. All three mammographically occult tumors were visible at US and MR imaging. US images of 21 tumors showed a solid, frequently oval-shaped, and hyperechoic mass in 13 tumors and random mixed hyper- and hypoechogenicity with associated architectural distortion in eight tumors. Dynamic contrast material-enhanced MR imaging of nine tumors showed large, lobular, and intensely and heterogeneously enhancing masses with rapid enhancement and the washout characteristics of a malignant lesion. CONCLUSION: A mass that shows homogeneous or heterogeneous hyperechogenicity at US (with associated architectural distortion) and has a hypervascular, hemorrhagic, and heterogeneous appearance and typical malignant enhancement characteristics at MR imaging should alert the radiologist to a possible diagnosis of angiosarcoma.

Comparison of full-field digital mammography and screen-film mammography for detection and characterization of simulated small masses.

OBJECTIVE: The two objectives of this study were to create an ex vivo phantom model that closely mimics human breast cancer for detection tasks and to compare the performance of full-field digital mammography with screen-film mammography in detecting and characterizing small breast masses in a phantom with a spectrum of complex tissue backgrounds. MATERIALS AND METHODS: Sixteen phantom breast masses of varying sizes (0.3-1.2 cm), shapes (round and irregular), and densities (high and low) were created from shaved tumor specimens and imaged using both full-field digital and screen-film mammography techniques. We created 408 detection tasks that were captured on 68 films. On each radiograph, six detection tasks were partially obscured by areas of varying breast-pattern complexity, including low (predominantly fatty), mixed (scattered fibroglandular densities and heterogeneously dense), and high (extremely dense) density patterns. Each detection task was scored using a five-point confidence scale by three mammographers. Receiver operating characteristic (ROC) curve analysis was performed to analyze differences in detection of masses between the two imaging systems, and sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were computed. RESULTS: Full-field digital mammography showed higher area under the ROC curve than screen-film mammography for detecting masses in each breast background and performed significantly better than screen-film mammography in mixed (p = 0.010), dense (p = 0.029), and all breast backgrounds combined (p = 0.004). Full-field digital mammography was superior to screen-film mammography for characterizing round and irregular masses and low- and high-density masses. CONCLUSION: Full-field digital mammography was significantly superior to screen-film technique for detecting and characterizing small masses in mixed and dense breast backgrounds in a phantom model.

Locoregional control of clinically diagnosed multifocal or multicentric breast cancer after neoadjuvant chemotherapy and locoregional therapy.

PURPOSE: The purpose was to assess whether patients with clinical multifocal or multicentric (MFMC) breast cancer determined by mammogram, ultrasound, or physical examination have inferior outcome compared with patients with clinical unicentric lesions. PATIENTS AND METHODS: We retrospectively analyzed 706 consecutive patients with stages I-III breast cancer treated at the M.D. Anderson Cancer Center (Houston, TX) from 1976 to 2003 who received neoadjuvant anthracycline-based chemotherapy followed by breast conservation therapy (BCT), mastectomy alone, or mastectomy plus postmastectomy radiation therapy. RESULTS: The mean follow-up was 66 months. At presentation, 97 of 706 patients had clinically MFMC disease (13.7%). The 5-year rate of locoregional failure was 10% for unicentric disease compared with 7% for MFMC disease (P = .78). Subset analyses of patients by treatment groups confirmed no statistical difference in locoregional control regardless of the type of locoregional treatment. Among patients with multifocal disease treated with BCT, there were no in-breast recurrences and one supraclavicular recurrence. Five-year disease-free survival and overall survival was equivalent between patients with MFMC and unicentric breast cancers. CONCLUSION: Patients with clinical MFMC breast cancer at the time of diagnosis treated with neoadjuvant chemotherapy followed by locoregional therapy have similar 5-year rates of locoregional control, disease-free survival, and overall survival as those with unicentric disease. Clinically detected MFMC disease did not predict for inferior outcome.

Specimen radiography in confirmation of MRI-guided needle localization and surgical excision of breast lesions.

OBJECTIVE: Confirmation of lesion retrieval after MRI-guided needle localization and surgical excision of breast lesions are difficult because the targeted lesion is not enhanced ex vivo. The aim of this study was to determine the feasibility of using specimen radiography to verify lesion removal after MRI-guided needle localization and surgical excision. CONCLUSION: To our knowledge, our study was the first to examine the use of specimen radiography in the localization and excision of breast lesions. Specimen radiography is a reliable, cost-effective alternative to repeated dynamic contrast-enhanced MRI for confirming lesion removal after surgery. Specimen radiography has the additional advantage of facilitating immediate assessment of surgical margins.

Imaging of breast cancer diagnosed and treated with chemotherapy during pregnancy.

PURPOSE: To retrospectively assess mammography, high-frequency-transducer ultrasonography (US), and color Doppler US for the initial and subsequent evaluation of breast cancer diagnosed and treated with chemotherapy during pregnancy. MATERIALS AND METHODS: A retrospective study of clinical records between January 1989 and December 2003 of women with breast cancer diagnosed and treated with chemotherapy during pregnancy was performed after waiver of informed consent was obtained. The study was approved by an institutional review board and was HIPAA compliant. Mammograms and sonograms were reviewed by two mammographers using the Breast Imaging Reporting and Data System (BI-RADS) mammographic and US lexicon. US assessment of the regional lymph node basins, including the axillary, infraclavicular, internal mammary, and supraclavicular regions, was documented. US was used to evaluate response to therapy in the breast and the regional lymph nodes in women who underwent neoadjuvant chemotherapy. RESULTS: Twenty-three women with 24 cancers that were imaged prior to surgery with mammography (n = 3), US (n = 4), or mammography and US (n = 17) were included in the study. The histologic diagnosis of the primary tumor was invasive ductal cancer in 22 lesions, and the diagnosis was invasive carcinoma in the two other cancers. The median age in this study was 34 years (range, 24-45 years). Of the 20 women who underwent preoperative mammography, findings were positive for malignancy in 18 of 20 (90%) cancers despite dense breast parenchymal patterns (BI-RADS types 3 and 4). A mass in all 21 cancers (100%) was depicted in the 20 women who underwent breast and nodal US. US correctly depicted axillary metastasis in 15 of 18 women who underwent US nodal assessment. Of the 12 patients who were evaluated for response to chemotherapy, US demonstrated complete response in two patients, partial response in three, stable findings in one, and progression of disease in six. CONCLUSION: Breast cancer diagnosed during pregnancy is mammographically evident despite dense parenchymal background. US, when performed, demonstrates all masses and provides information regarding response to neoadjuvant chemotherapy.

Extramedullary relapse in a patient with acute promyelocytic leukemia: successful treatment with arsenic trioxide, all-trans retinoic acid and gemtuzumab ozogamicin therapies.

Acute promyelocytic leukemia (APL) is characterized by the presence of the t(15;17) translocation, resulting in the PML-RAR fusion protein. Standard treatment consists of the combination of all-trans retinoic acid (ATRA) with an anthracycline that results in complete remission (CR) rates in excess of 90%. Recently, several new agents have been shown to have clinical activity in APL. These include a liposomal formulation of ATRA (lipo-ATRA), and gemtuzumab ozogamicin (GO). Herein, we report a patient with APL who relapsed with extramedullary disease 2.5 years after lipo-ATRA therapy and was successfully treated with the sequence of A2O3, ATRA, and GO and we summarize our experience with patients with isolated extramedullary relapse in APL.

Mammographic-pathologic correlation of apocrine metaplasia diagnosed using vacuum-assisted stereotactic core-needle biopsy: our 4-year experience.

OBJECTIVE: To determine whether focal apocrine metaplasia of the breast has distinctive mammographic characteristics, we evaluated apocrine metaplasia diagnosed by vacuum-assisted stereotactic core-needle biopsy and correlated mammographic imaging and histopathologic findings. MATERIALS AND METHODS: We retrospectively reviewed our institutional database for records of all vacuum-assisted stereotactic core-needle biopsies performed during a 4-year period. Five hundred thirty-eight lesions were biopsied, of which 302 (56%) were benign. Apocrine metaplasia was diagnosed in 37 lesions. In 11 of these 37 lesions, apocrine metaplasia made up more than 50% of the lesion sampled. RESULTS: On mammography, eight cases (73%) appeared as new or increasing calcifications, and three cases (27%) appeared as new or enlarging equal-density masses (0.6-1.2 cm). Calcifications were heterogeneous in five lesions (63%), amorphous in two (25%), and punctate in one (12%); one heterogeneous cluster of calcifications (12%) also contained milk of calcium. The pattern of calcification distribution was clustered in five lesions (63%), multiple clusters in two (25%), and linear in one (12%). Two masses (67%) were lobular, and one (33%) was round. Two borders (67%) were microlobulated, and one (33%) was circumscribed. CONCLUSION: Apocrine metaplasia is a benign condition commonly associated with other fibrocystic changes. Lesions composed of more than 50% focal apocrine metaplasia are relatively uncommon. A new or enlarging lobular, microlobulated mass or heterogeneous calcification cluster may represent apocrine metaplasia. Because no distinguishing mammographic features are present to require follow-up by imaging, needle biopsy is required for definitive diagnosis.