Radial sclerosing lesions found on core needle biopsy: excision can be safely avoided.

AIMS: Radial sclerosing lesions (RSLs) are benign breast lesions composed of glandular and epithelial proliferations with stellate architecture and fibro-elastotic stroma, which can mimic invasive carcinoma on imaging. Surgical management following a core biopsy diagnosis of RSLs remains controversial. METHODS AND RESULTS: We retrospectively identified core biopsies with RSLs without atypia who underwent subsequent surgical excision between 2015 and 2021. All core biopsy slides were reviewed to confirm the diagnosis. Imaging was reviewed to determine radiological-pathological concordance. An upgrade was defined as invasive carcinoma or ductal carcinoma in situ (DCIS) in the excision. The final cohort consisted of 130 core biopsies from 124 women (median age = 52 years, range = 27-76). The imaging modality was mammogram in 52 (40%) cases, MRI in 52 (40%) and ultrasound in 26 (20%). One hundred and seven (82%) core biopsies were vacuum-assisted and 23 (18%) were ultrasound-guided without vacuum assistance. The median lesion size on imaging was 9 mm (range = 2-41). Overall, two (1%) cases were upgraded at excision, including one microinvasive lobular carcinoma and one 2 mm focus of invasive mammary carcinoma with associated DCIS. In both cases, the upgraded foci of carcinoma were not closely associated with the biopsy site and were considered incidental upgrades. CONCLUSIONS: This study adds to the body of literature supporting observation, rather than routine excision of radial sclerosing lesions without atypia.

Nonneoplastic and neoplastic sclerosing lesions of the breast.

Sclerosing lesions of the breast encompass a spectrum of benign and malignant entities and often pose a diagnostic challenge. Awareness of key morphologic features and pitfalls in the assessment of morphology and immunophenotype is essential to avoid over- or underdiagnosis and ensure optimal clinical management. This review summarizes nonneoplastic sclerosing lesions such as radial scar/complex sclerosing lesion, sclerosing adenosis, sclerosing intraductal papilloma, sclerosing variants of ductal adenoma and nipple adenoma, and fibroadenoma with extensive sclerosis, including their clinical presentation, characteristic morphology, differential diagnostic considerations, appropriate immunohistochemical work-up, when needed, and the clinical significance. In addition, atypical or neoplastic entities (such as atypical ductal hyperplasia, ductal carcinoma in situ, low-grade adenosquamous carcinoma, and fibromatosis-like metaplastic carcinoma) that can involve these sclerosing lesions are also briefly discussed.

Low-grade adenosquamous carcinoma of the breast: a clinical, morphological and immunohistochemical analysis of 25 patients.

AIMS: Due to its rarity and non-specific clinical and pathological features, low-grade adenosquamous carcinoma (LGASC) of the breast continues to pose diagnostic challenges. Unlike other triple-negative breast carcinomas, LGASC tends to have an indolent clinical behaviour. It is essential to recognise this lesion for accurate diagnosis and appropriate management. METHODS AND RESULTS: Twenty-five cases of LGASC were identified in our archives and collaborating institutes. Cases of LGASC with dominant coexisting other type carcinomas were excluded. We studied the clinical presentation, morphological features, patterns of the commonly used immunohistochemical stains and follow-up. In our cohort, LGASC was commonly located at the outer aspect of the breast and associated with intraductal papilloma. The morphology of LGASC is characterised by infiltrating small glands and nests with variable squamous differentiation. We also found cuffing desmoplastic (fibrolamellar) stromal change in 75% of patients and peripheral lymphocytic aggregates in 87.5% of patients. P63 and smooth muscle myosin (SMM) were the most common myoepithelial markers used to assist in diagnosis. P63 often stained peripheral tumour cells surrounding invasive glands (circumferential staining in 80% of the cases), mimicking myoepithelial cells. It also stained the small nests with squamous differentiation. However, SMM was negative in 63% of the cases. The vast majority of our cases were triple-negative; only a few had focal and weak expressions of ER and PR. One patient who did not have excision developed lymph node metastasis. Most patients underwent excision or mastectomy with negative margins as surgical treatment; there were no recurrences or metastases in these patients with clinical follow-ups up to 108 months. CONCLUSIONS: LGASC has some unique, although not entirely specific, morphological features and immunohistochemical staining patterns. Fibrolamellar stromal change, peripheral lymphocytic aggregates and variable staining of p63 and SMM are valuable features to facilitate the diagnosis.

Breast MRI Does Not Help Differentiating Radial Scar With and Without Associated Atypia or Malignancy.

PURPOSE: To review breast magnetic resonance imaging (MRI) features of radial scar (RS) with and without associated atypia/malignancy. METHODS: Twenty-eight (mean age 56.8) patients diagnosed with 30 biopsy-proven RS (n = 25, ultrasound-guided 14-gauge, n = 5, stereotactically guided 9-gauge) subsequently underwent breast MRI followed by surgery. Magnetic resonance imaging protocol included axial T1, axial fat sat T2, and postgadolinium in axial and sagittal planes. Two radiologists reviewed the mammographic and MRI findings in consensus according to the Breast Imaging Reporting and Data System lexicon. RESULTS: Of the 30 RSs excised surgically, 14 (14/30, 47.7%) were not associated with atypia/malignancy while atypia/malignancy was found in 16 (16/30, 53.3%) RSs. Three (3/30, 10%) RS lesions did not enhance on dynamic MR. Mean lesion size on MRI was 1.4 cm (range, 0.5-5 cm). Seventeen (17/30, 56.7%) lesions presented as nonmass enhancement and 9 (9/30, 30%) as masses. Nonmass lesions showed focal distribution (13/17, 76.5%) and heterogeneous enhancement (15/17, 88.2%). Masses showed irregular shape and margins (6/9, 67%) and heterogeneous enhancement (8/9, 89%). Multivariate analysis did not show any significant difference in MRI presentation between RS only and RS associated with atypia/malignancy. CONCLUSION: Breast MRI does not help differentiate between RS with or without associated atypia/malignancy.

Radial scars and complex sclerosing lesions on core needle biopsy of the breast: upgrade rates and long-term outcomes.

PURPOSE: Radial scars and complex sclerosing lesions of the breast are part of a group of "indeterminate" breast lesions, which are excised due to risk of coexistent carcinoma. The aim of this study was to assess rate of upgrade of these lesions to invasive and in situ carcinoma and to quantify the risk of development of subsequent cancer in women diagnosed with these lesions. METHODS: A retrospective review of a prospectively maintained breast screening database was performed. All patients with radial scar identified at either core biopsy or final excision biopsy between January 2006 and July 2012 were identified. Full pathological reports for both core biopsy and final excision biopsy were reviewed. Patient outcomes were followed for a mean of 117.1 months. RESULTS: Of 451 B3 biopsies performed at our screening unit, 95 (22%) were found to have a radial scar or complex sclerosing lesion (CSL) on core needle biopsy. Within this group, 77 had no atypia on CNB, with 7 (9%) upgraded to invasive/in situ carcinoma on final excision. Of nine with definite atypia on CNB, 3 (33%) were upgraded. In those patients without atypia or malignancy on final excision, 7.5% developed cancer during 10-year follow-up. CONCLUSION: Patients with radial scar with atypia have a higher risk of upgrade to malignancy. Further research is needed to identify which patients may safely avoid excision of radial scar. Patients with a diagnosis of radial scar on CNB are at increased subsequent risk of breast cancer and may benefit from additional screening.

Reducing indications for radial scar surgical excision in Slovenian breast cancer screening program.

PURPOSE: Management of the radial scar (RS)/complex sclerosing lesion (CSL) diagnosed by core needle biopsy (CNB) in breast cancer screening population (BCSP) is controversial due to its intrinsic malignant potential. We aimed to determine (i) the rate of upgrade of the RS/CSL to malignant lesions and (ii) radiological characteristics and CNB histopathological findings of the lesions related to the upgrade of the RS/CSL to malignant lesions after surgical excision in our BCSP. PATIENTS AND METHODS: Database of Slovenian National Breast Cancer Screening Program was checked for terms RS/CSL in all patients who underwent CNB in the period 2008-2018. The ratios of upgrade from CNB RS/SCL to malignant lesions after surgical excision were calculated with specific interest to the radiological characteristics and the CNB patohistologically findings of the lesions. RESULTS: Of 162 patients with diagnosis of RS/CSL on the CNB, 121/156 (78%) cases underwent surgical excision. 6 of 121 (5%) cases were upgraded to a malignant diagnosis in surgical specimen, 3 cases of invasive carcinoma and 3 cases of DCIS, respectively. Five of the upgraded cases (5/6, 83.3%) showed atypical epithelial proliferative lesions (AEPL) on CNB. In one upgraded case without AEPL the lesion presented as 33 mm architectural distortion with microcalcifications on the mammogram. CONCLUSIONS: In BCSP setting RS/CSL without AEPL/papilloma and those measuring less than 2 cm in the largest diameter can be followed radiologically. Increasing the number of cores and adequate sampling of the periphery and the centre of the RS/CSL improves the pick-up rate of associated atypia/malignancy.

Management of radial scars/complex sclerosing lesions of the breast diagnosed on vacuum-assisted large-core biopsy: is surgery always necessary?

AIMS: The diagnosis of radial scars/complex sclerosing lesions (RSs/CSLs) onpercutaneous biopsy carries a risk of histological underestimation. Consequently, surgical excision is often performed in order to exclude a possible associated malignancy. The aim of this study was to assess the rate of 'upgrade to carcinoma' upon subsequent surgical excision of RS/CSL cases diagnosed on vacuum-assisted large-core biopsy (VALCB). We also analysed the risk factors for upgrade in order to determine a subset of patients who could avoid surgery and benefit from conservative management with clinical and imaging follow-up. METHODS AND RESULTS: This was a retrospective observational single-centre study on 174 consecutive RS/CSL cases diagnosed on VALCB from May 2008 to October 2015. Univariate analysis was performed to identify clinical, radiological and histological risk factors for upgrade. Surgical excision was performed following VALCB diagnosis of 88 RS/CSL cases with or without associated atypia. The overall rate of surgical upgrade to carcinoma was 9.1% (8/88). None of the benign biopsies without atypia was surgically upgraded. Additional to atypia, risk factors for upgrade were non-incidental finding of the RS/CSL, the mammographic appearance, and the number of fragments obtained during the biopsy procedure (P < 0.05). CONCLUSION: We demonstrate that VALCB revealing an RS/CSL is reliable for excluding malignancy when there is no associated atypia and when radiological and histological findings are concordant. In such cases, surgery can be avoided in favour of clinical and imaging follow-up. When an RS/CSL is associated with atypia, the decision to perform surgical excision depends on other associated risk factors.

[Complex morphological (cytological, histological) diagnostics of pipillomatosis nipping in combination with subareolar sclrose protective hyperplasia (case from practice).]

A case of benign proliferative formation of the mammary gland of a rare histological form - subareolar sclerosing ductal hyperplasia in combination with papillomatosis of the nipple is presented. Pathology belongs to the group of complex sclerosing lesions. When setting the morphological (cytological, histological) diagnosis, it is necessary to take into account the clinical picture - the state of the nipple-areola complex, in particular, the presence / absence of nipple discharge and its involvement in the pathological process.

Radial scars/complex sclerosing lesions of the breast: radiologic and clinicopathologic correlation.

BACKGROUND: We investigated the radiologic and clinical findings of radial scar and complex sclerosing lesions, and evaluated the rate of pathologic upgrade and predicting factors. METHODS: From review of our institution's database from January 2006 to December 2012, we enrolled 82 radial scars/complex sclerosing lesions in 80 women; 51 by ultrasound guided core needle biopsy, 1 by mammography-guided stereotactic biopsy, and 38 by surgical excision. The initial biopsy pathology revealed that 53 lesions were without high risk lesions and 29 were with high risk lesions. Radiologic, clinical and pathological results were analyzed statistically and upgrade rates were calculated. RESULTS: Of the 82 lesions, 64 (78.0%) were surgically excised. After surgical excision, two were upgraded to DCIS and two were upgraded to lesions with high risk lesions. The rate of radial scar with high risk lesions was significantly higher in the surgical excision group (11.1% vs. 42.2%, p = 0.015), which also demonstrated larger lesion size (10.7 ± 6.5 vs. 7.1 ± 2.6 mm, p = 0.001). The diagnoses with high risk lesions on final pathological results showed older age (52.9 ± 6.0 years vs. 48.4 ± 6.7 years, p = 0.018). CONCLUSIONS: Radial scars with and without high risk lesions showed no statistically significant differences in imaging, and gave relatively low cancer upgrade rates.

Radial scars without atypia in percutaneous biopsy specimens: can they obviate surgical biopsy? / Cicatriz radial sin atipia en biopsia percutánea. ¿Puede evitarse la biopsia quirúrgica?

OBJECTIVE: To evaluate the need for surgical biopsy in patients diagnosed with radial scars without atypia by percutaneous biopsy. MATERIAL AND METHODS: In this retrospective observational study, we selected patients with a histological diagnosis of radial scar in specimens obtained by percutaneous biopsy during an 8-year period. The statistical analysis was centered on patients with radial scar without atypia (we assessed the radiologic presentation, the results of the percutaneous biopsy, and their correlation with the results of surgical biopsy and follow-up) and we added the patients with atypia and cancer in the elaboration of the diagnostic indices. RESULTS: We identified 96 patients with radial scar on percutaneous biopsy; 54 had no atypia, 18 had atypia, and 24 had cancer. Among patients with radial scar without atypia, there were no statistically significant differences between patients who underwent imaging follow-up and those who underwent surgical biopsy (p>0.05). The rate of underdiagnosis for percutaneous biopsy in patients without atypia was 1.9%. The rates of diagnosis obtained with percutaneous biopsy in relation to follow-up and surgical biopsy in the 96 cases were sensitivity 92.3%, specificity 100%, positive predictive value 100%, negative predictive value 97.2%, and accuracy 97.9%. The area under the ROC curve was 0.96 (p<0.001), and the kappa concordance index was 0.95 (p<0.001) CONCLUSIONS: We consider that it is not necessary to perform surgical biopsies in patients with radial scars without atypia on percutaneous biopsies because the rate of underestimation is very low and the concordance between the diagnosis reached by percutaneous biopsy and the definitive diagnosis is very high.

Beware it's benign: A unique case of concomitant benign breast pathologies.

Complex sclerosing lesion (CSL)/radial scar of breast is a benign entity that can pose a diagnostic challenge due to resemblance to breast carcinoma on imaging. Hamartoma are uncommon benign tumors, composed of disorganized mixture of glandular, fibrous, and adipose tissues, which can exhibit classical imaging characteristics. Here we describe a case of concomitant CSL and hamartoma in left beast, of which CSL presented as suspicious mass on imaging but was ultimately confirmed to be benign on histopathology with 4 years of documented stability.

Distance of Biopsy-Confirmed High-Risk Breast Lesion from Concurrently Identified Breast Malignancy Associated with Risk of Carcinoma at the High-Risk Lesion Site.

High-risk breast lesions including incidental intraductal papilloma without atypia (IPA), lobular hyperplasia (LCIS or ALH), flat epithelial atypia (FEA) and complex sclerosing lesion (CSL) are not routinely excised due to low upgrade rates to carcinoma. We aim to identify features of these lesions predictive of upgrade when identified concurrently with invasive disease. Methods: A single-center retrospective cohort study was performed for patients who underwent multi-site lumpectomies with invasive disease at one site and a high-risk lesion at another site between 2006 and 2021. A multinomial logistic regression was performed. Results: Sixty-five patients met the inclusion criteria. Four patients (6.2%) had an upgrade to in situ disease (DCIS) and one (1.5%) to invasive carcinoma. Three upgraded high-risk lesions were ipsilateral to the concurrent carcinoma and two were contralateral. In the multivariate model, a high-risk lesion within 5 cm of an ipsilateral malignancy was associated with increased risk of upgrade. The 3.8% upgrade rate for high-risk lesions located greater than 5 cm from ipsilateral malignancy or in the contralateral breast suggests that omission of excisional biopsy may be considered. Excisional biopsy of lesions within 5 cm of ipsilateral malignancy is recommended given the 25% upgrade risk in our series.

Evaluation of Benign Breast Diseases With or Without Atypical Epithelial Hyperplasia Accompanying Radial Scars.

Objective: A radial scar (RS) is a benign breast lesion (BBL) that has an obscure etiology. RS is easily confused with breast carcinoma and therefore correct identification radiologically and pathologically is important. The aim of this study was to determine the incidence of atypical lesions by evaluating RS detected with BBL and to investigate whether atypia and RS are related to their characteristics. Materials and Methods: A total of 1.370 patients with a diagnosis of BBL postoperatively in a single department were analyzed retrospectively. Forty-six confirmed RS/complex sclerosing lesion (CSL) cases were selected. The demographic and clinical characteristics of the patients and the relationship between RS and other BBL were evaluated. In addition, the relationship between RS/CSL and the presence of atypia was interpreted. Results: The mean age was 45.17±8.72 years. Spiculated lesion (34.8%) on mammography and microcalcification (37%) on histopathological examination were the most common features. The most common BBL accompanying RS/CSL was adenosis. Atypical epithelial hyperplasia (AEH) was presented in 15 (32.6%) of those diagnosed with RS. Although all patients were benign, the frequency of AEH accompanying RS was found to be significantly higher. The mean size of RS was 10.8±8.4 mm (2-30 mm). The size of RS/CSL was not significantly associated with atypia. Conclusion: RS/CSLs usually present as suspicious lesions that must be distinguished radiologically from malignancy. However RS, which can be present with malign breast lesions, can be also seen with all BBL. Therefore, core biopsy and/or excisional biopsy continue to be important for definitive histopathological diagnosis.

Magnetic Resonance Imaging Assessment of Radial Scars/complex Sclerosing Lesions of the Breast.

PURPOSE: To describe the magnetic resonance characteristics of radial scars/complex sclerosing lesions (RS/CSL) of the breast using the current BI-RADS lexicon. To investigate the value of diffusion weighted imaging to predict malignancy. PATIENTS AND METHODS: From 2010 to 2017, we have found 25 women with architectural distortion at mammography who underwent surgical resection with a final hystopathologic report of RS/CSL. For the description of MRI findings, we adhered to BI-RADS classification (5th edition). RESULTS: The final pathological diagnosis was: "pure" RS/CSL in 7 cases (28%), RS/CSL with associated high risk lesions in 12 (48%) and 6 cases (24%) were associated with malignancy. Magnetic resonance findings: four of 25 negative or focus. Five of 25 mass enhancement: irregular, non circumscribed spiculated mass with heterogeneous or rim enhancement and most with type II curves. Sixteen of 25 non mass enhancement: focal or linear distribution and heterogeneous internal enhancement most with type I curves. Six of 25 had cancer associated with the complex sclerosing lesion. All six showed non-mass enhancement. Two cases with invasive breast carcinoma had ADC values under 1.15 x10-3 mm/s while most of the rest had the values above. CONCLUSION: Most RS/CSL showed enhancement at MR. The predominant pattern was a non-mass, focal, heterogeneous internal enhancement with type 1 curves. All cases with associated cancer showed non mass enhancement. Invasive breast cancers had ADC values < 1.15 10-3 s/mm2.

Upstage rate of radial scar/complex sclerosing lesion identified on core needle biopsy.

BACKGROUND: We assessed the cancer upstage rate of Radial Scars (RS), and Complex Sclerosing Lesions (CSL), and risk-stratified lesions based on radiological and pathological features. METHODS: Characteristics of RS/CSL treated from 2013 to 2018 were examined for features associated with cancer. RESULTS: 78 RS/CSL were found on core needle biopsy (CNB) and surgically excised. 9 (11.5%) lesions were upstaged. Upstaged patients were older (66 vs 51, p = 0.033). More upstaged lesions were accompanied by a mass on both mammography (87.5% vs. 30.0%, p = 0.005) and ultrasound (100.0% vs. 62.8%, p = 0.043). 20.5% of lesions biopsied under ultrasound guidance with small needles (14-18G) were upstaged, but no lesions biopsied under stereotactic guidance with large needles (9-12 G) with vacuum assistance were upstaged (p = 0.009). CONCLUSIONS: Excision of RS/CSL seen on CNB is warranted, especially if the patient is older, the CNB is performed under ultrasound guidance with small needles, or if a mass is present on imaging.

Pure Radial Scars Do Not Require Surgical Excision When Concordant and Benign at Image-guided Breast Biopsy.

OBJECTIVE: To determine the best management option (surgical excision versus imaging surveillance) following the diagnosis of pure radial scars (RSs) and RSs with associated additional high-risk lesions (HRLs) encountered on percutaneous core-needle breast biopsy. METHODS: An IRB-approved retrospective review of the breast imaging reporting system database was performed to identify all cases of pure RS alone or RS plus an additional HRL (papilloma, atypia, lobular neoplasia) diagnosed on core-needle biopsy, from 2007 to 2016, at four breast centers in our institution. Cases with associated malignancy, discordant radiologic-pathologic results, or those lost to follow-up were excluded. The remaining cases were evaluated to determine results of either subsequent surgical excision or long-term follow-up imaging (minimum of two years). Additional data recorded included clinical presentation, breast density, personal and family history of breast cancer, lesion imaging characteristics, and biopsy method. RESULTS: The study cohort included 111 patients with 111 lesions: 56.8% (63/111) with RS alone (pure) and 43.2% (48/111) with RS plus additional HRL(s). Out of the 63 radiologic-pathologic concordant pure RSs, there were no upgrades to malignancy in 51 subsequent surgical excisions or 12 long-term surveillance cases (0/63, 0%). Out of the 48 RSs plus additional HRL(s), there were 2 upgrades to malignancy (2/48, 4.2%). CONCLUSION: Cases of radiologic-pathologic concordant pure RS diagnosed at core-needle biopsy do not require surgical excision. On the other hand, surgical excision should be considered for RS plus additional HRLs diagnosed at core-needle biopsy.

Radial scar of the breast: Is it possible to avoid surgery?

INTRODUCTION: Breast radial scar (RS) management remains controversial. The need for surgical excision is supported by the concern of an associated high-grade lesion missed in the biopsy. The aim of this study was to assess histologic upgrade rate after a percutaneous biopsy, to determine if vacuum assisted biopsy prevents the need for subsequent RS surgical resection and to evaluate the upgrade risk factors. PATIENTS AND METHODS: This was a uni-institutional retrospective study of consecutive patients with RS histologically diagnosed from January 2010 to December 2015. RESULTS: A total of 113 cases of RS were diagnosed. We verify that there was a histologic upgrade in 22 (19.5%) cases. The upgrade risk factors were the type of biopsy performed, the presence of atypia, the presence of calcifications and the number of fragments obtained in the biopsy (p < 0.05). The biopsy type was vacuum assisted in 25 (22.1%). The upgrade rate in the vacuum assisted biopsy group was 4.0%, whereas in the standard core needle biopsy group was 23,9% (p = 0.041). DISCUSSION AND CONCLUSION: We demonstrated that the risk of upgrade after a RS diagnosis depends on the type of biopsy performed, the presence of atypia, the presence of calcifications and the number of fragments obtained. When a standard core biopsy is performed the risk of upgrade and malignancy is not negligible, and surgery is indicated. When the biopsy is vacuum assisted, the risk of upgrade and malignancy is significantly decreased and so the indication for excisional biopsy seems not to be so imperative.

Next generation sequencing of the nidus of early (adenosquamous proliferation rich) radial sclerosing lesions of the breast reveals evidence for a neoplastic precursor lesion.

We sought to determine if adenosquamous proliferation of early cellular radial sclerosing lesions of the breast harbours hot spot mutations and to help clarify its relationship to low-grade adenosquamous carcinoma as a potential form of early neoplasia. Four low-grade adenosquamous carcinomas, early radial sclerosing lesions from 13 individuals, and 4 benign proliferative breast lesions were microdissected and assessed with a 50-gene Hot-spot cancer panel. Early radial sclerosing lesions were selectively microdissected concentrating on their adenosquamous proliferation (nidus). Hot spot mutations in PIK3CA were detected in ten (77% of) radial sclerosing lesions, in one low-grade adenosquamous carcinoma, and in usual ductal hyperplasia and apocrine adenosis. Over three quarters of individuals with cellular (adenosquamous proliferation rich) early radial sclerosing lesions tested harboured somatic mutations in PIK3CA suggesting that adenosquamous proliferation is a clonal lesion. Its relationship to low-grade adenosquamous carcinoma remains unclear in view of the small sample size and unmatched radial sclerosing lesions and low-grade adenosquamous carcinomas.

Mammographically Occult Asymptomatic Radial Scars/Complex Sclerosing Lesions at Ultrasonography-Guided Core Needle Biopsy: Follow-Up Can Be Recommended.

An increasing number of radial scars are detected by ultrasound (US), but their management is controversial. This study investigated the upgrade rate in mammographically occult radial scars/complex sclerosing lesions without epithelial atypia at US-guided 14-gauge core needle biopsy in asymptomatic patients. Nineteen mammographically occult benign radial scars/complex sclerosing lesions (median size, 7 mm; range, 3-23 mm) were included. Patients underwent surgical excision (n = 10) or vacuum-assisted excision, with follow-up US at least 6 mo after benign vacuum-assisted excision results (n = 8), or underwent US follow-up for 2 y after core needle biopsy (n = 1). Any cases with change in diagnosis to high-risk lesions or malignancy at excision were considered upgrades. The upgrade rate was 0.0%. Based on US findings, 15.8% (3/19) were Breast Imaging Reporting and Data System (BI-RADS) category 3, 68.4% (13/19) were BI-RADS category 4a and 15.8% (3/19) were BI-RADS category 4b. Follow-up with US can be considered for mammographically occult benign radial scar/complex sclerosing lesions diagnosed by US core needle biopsy in asymptomatic patients.