Borderline atypical ductal hyperplasia/low-grade ductal carcinoma in situ on breast needle core biopsy should be managed conservatively

Real-World Diagnostic Accuracy of the On-Site Cytopathology Advance Report (OSCAR) Procedure Performed in a Multidisciplinary One-Stop Breast Clinic

Fine-needle aspiration (FNA) cytology has been widely used for the diagnosis of breast cancer lesions with the objective of differentiating benign from malignant masses. However, the occurrence of unsatisfactory samples and false-negative rates remains a matter of concern. Major improvements have been made thanks to the implementation of rapid on-site evaluation (ROSE) in multidisciplinary and integrated medical settings such as one-stop clinics (OSCs). In these settings, clinical and radiological examinations are combined with a morphological study performed by interventional pathologists. The aim of our study was to assess the diagnostic accuracy of the on-site cytopathology advance report (OSCAR) procedure on breast FNA cytologic samples in our breast OSC during the first three years (April 2004 till March 2007) of its implementation. To this goal, we retrospectively analyzed a series of 1820 breast masses (1740 patients) radiologically classified according to the American College of Radiology (ACR) BI-RADS lexicon (67.6% being either BI-RADS 4 or 5), sampled by FNA and immediately diagnosed by cytomorphology. The clinicoradiological, cytomorphological, and histological characteristics of all consecutive patients were retrieved from the hospital computerized medical records prospectively registered in the central information system. Histopathological analysis and ultrasound (US) follow-up (FU) were the reference diagnostic tests of the study design. In brief, we carried out either a histopathological verification or an 18-month US evaluation when a benign cytology was concordant with the components of the triple test. Overall, histology was available for 1138 masses, whereas 491 masses were analyzed at the 18-month US-FU. FNA specimens were morphologically nondiagnostic in 3.1%, false negatives were observed in 1.5%, and there was only one false positive (0.06%). The breast cancer prevalence was 62%. Diagnostic accuracy measures of the OSCAR procedure with their 95% confidence intervals (95% CI) were the following: sensitivity (Se) = 97.4% (96.19-98.31); specificity (Sp) = 94.98% (92.94-96.56); positive predictive value (PPV) = 96.80% (95.48-97.81); negative predictive value (NPV) = 95.91% (94.02-97.33); positive likelihood ratio (LR+) = 19.39 (13.75-27.32); negative predictive ratio (LR-) = 0.03 (0.02-0.04), and; accuracy = 96.45% (95.42-97.31). The respective positive likelihood ratio (LR+) for each of the four categories of cytopathological diagnoses (with their 95% CI) which are malignant, suspicious, benign, and nondiagnostic were 540 (76-3827); 2.69 (1.8-3.96); 0.03 (0.02-0.04); and 0.37 (0.2-0.66), respectively. In conclusion, our study demonstrates that the OSCAR procedure is a highly reliable diagnostic approach and a perfect test to select patients requiring core-needle biopsy (CNB) when performed by interventional cytopathologists in a multidisciplinary and integrated OSC setting. Besides drastically limiting the rate of nondiagnostic specimens and diagnostic turn-around time, OSCAR is an efficient and powerful first-line diagnostic approach for patient-centered care.

High-risk and selected benign breast lesions diagnosed on core needle biopsy: Evidence for and against immediate surgical excision

The vast majority of image-detected breast abnormalities are diagnosed by percutaneous core needle biopsy (CNB) in contemporary practice. For frankly malignant lesions diagnosed by CNB, the standard practice of excision and multimodality therapy have been well-defined. However, for high-risk and selected benign lesions diagnosed by CNB, there is less consensus on optimal patient management and the need for immediate surgical excision. Here we outline the arguments for and against the practice of routine surgical excision of commonly encountered high-risk and selected benign breast lesions diagnosed by CNB. The entities reviewed include atypical ductal hyperplasia, atypical lobular hyperplasia, lobular carcinoma in situ, intraductal papillomas, and radial scars. The data in the peer-reviewed literature confirm the benefits of a patient-centered, multidisciplinary approach that moves away from the reflexive "yes" or "no" for routine excision for a given pathologic diagnosis.

Atypical Ductal Hyperplasia-Ductal Carcinoma In Situ Spectrum: Diagnostic Considerations and Treatment Impact in the Era of Deescalation

As the first node in treatment algorithms for breast disease, pathologists have the potential to play a critical role in refining appropriate therapy for lesions in the atypical ducal hyperplasia-ductal carcinoma in situ (ADH-DCIS) spectrum by conservatively approaching diagnosis of lesions limited in size on core needle biopsy. Appropriate efforts to downgrade the diagnosis of lesions at the borderline of ADH and DCIS will certainly lead to more breast conservation and avoid the common morbidities of mastectomy, sentinel node biopsy, and radiation therapy. Whether results of clinical trials of active surveillance will successfully identify a subset of women who may successfully forgo even limited breast-conserving surgery is eagerly anticipated. Given the increasing concern that a significant number of women with DCIS are overtreated, identification of patients at very low risk for progression who may forgo surgery and radiation therapy safely is of significant interest.

Type of Architecture, Presence of Punctate Necrosis, and Extent of Involvement in Atypical Ductal Hyperplasia Can Predict the Diagnosis of Breast Carcinoma on Excision: A Clinicopathologic Study of 143 Cases

The literature shows a wide range in the frequencies of finding breast carcinoma in the excised specimens following a biopsy diagnosis of atypical ductal hyperplasia (ADH), likely due to a poor diagnostic reproducibility among different pathologists as well as an inherent heterogeneity in ADH. We evaluated whether histologic subtyping of ADH would help predict the risk of breast carcinoma. Our study consisted of 143 cases of ADH diagnosed by core needle biopsy and followed by excision. Of these, 54 cases (37.8%) showed carcinoma in the excised specimens (47 cases of ductal carcinoma in situ alone, 3 cases of invasive ductal carcinoma alone, and 4 cases of mixed invasive ductal carcinoma and ductal carcinoma in situ). We arbitrarily divided ADH into two subtypes: type A was considered when one or more ducts were completely replaced by low-grade ductal carcinoma in situ type cells but the lesion was <2 mm and type B was considered when one or more ducts were partially involved by low-grade ductal carcinoma in situ type cells regardless of lesion size. Type A was associated with a significantly higher frequency of breast carcinoma (63.6%) than type B (30.0%). ADH containing punctate necrosis showed a higher association of carcinoma (66.7%) compared to those without necrosis (35.1%). Within type B ADH, involvement of 3 or more foci had a higher frequency of carcinoma (50.0%) than involvement of fewer foci (26.6%). These histologic features of ADH may prove useful in predicting the likelihood of breast carcinoma and provide helpful information for patient's management.

Atypical ductal hyperplasia bordering on DCIS on core biopsy is associated with higher risk of upgrade than conventional atypical ductal hyperplasia

PURPOSE

Upgrade rates of conventional ADH are reported at 10-30%; however, rates for ADH bordering on DCIS (ADH-BD) are largely unknown. We examined the upgrade rate of ADH-BD and core needle biopsy (CNB) features associated with upgrade. Surgical management in patients with concurrent ipsilateral breast cancer (BC) was also examined.

METHODS

From 2000 to 2018, women with CNB diagnosis of ADH-BD were prospectively identified. Women with pure ADH-BD and concurrent ipsilateral ADH-BD/BC were analyzed separately, and upgrade rates were calculated. CNB features associated with upgrade and type of surgery were examined in women with pure ADH-BD; CNB features and concurrent pathology associated with upgrade were examined in women with ipsilateral BC.

RESULTS

108/236 (46%) patients with pure ADH-BD on CNB had DCIS (40%) or invasive carcinoma (6%) on surgical excision. DCIS or invasive carcinoma was more frequently found on excision of a mass that yielded ADH-BD on biopsy than excision of calcifications (65% vs 38%; p < 0.001). The breast conservation success rate was high (80%) in patients who upgraded, despite a high re-excision rate of 46%. The upgrade rate of ADH-BD in women with concurrent ipsilateral BC was 41%. Most women (94%) with ADH-BD in the same quadrant as the BC were candidates for breast conserving surgery, with a success rate of 89%.

CONCLUSION

The upgrade rate for pure ADH-BD is significantly higher than that reported for women with conventional ADH, especially in women with a mass on imaging. The upgrade rate of concurrent ipsilateral ADH-BD and BC is similarly high. Excision with a margin of normal tissue and specimen inking should be routine to minimize the need for re-excision.

Diagnostic upgrade of atypical ductal hyperplasia of the breast based on evaluation of histopathological features and calcification on core needle biopsy

AIMS

Atypical ductal hyperplasia (ADH) of breast is increasingly diagnosed in core needle biopsy (CNB). As higher-grade lesions were found in the excision in a substantial proportion of ADH on CNB, factors predicting risk of subsequent upgrade are clinically significant. This study aims to investigate relevant histopathological factors in CNB that could predict diagnostic upgrade at excision.

METHODS AND RESULTS

One hundred and forty-three cases of CNB with paired subsequent excision were evaluated for multiple clinicopathological parameters related to CNB sampling, ADH morphology, calcification and other co-existing histological features, and which of these parameters were associated with diagnostic upgrade at subsequent excisions were determined. Forty-eight cases (34.3%) were upgraded to malignancy, including 15 invasive cancers and 33 ductal carcinomas in situ (DCIS). An increased tissue area occupied by ADH (P = 0.026), a higher number of ADH foci (P = 0.004), the presence of solid pattern (P = 0.037) and older age (P = 0.012) were positively associated with upgrade, while negative associations were found with the presence of micropapillary pattern (P = 0.025), co-existing columnar cell lesions (CCL) (P = 0.001) and the presence of calcifications (P = 0.009). Multivariate logistic regression analysis showed that the number of ADH foci (HR = 2.810, P = 0.013) was an independent positive predictor, while co-existing CCL (HR = 0.391, P = 0.013) was an independent negative predictor for upgrade.

CONCLUSIONS

Patients with ADH in CNB showing the presence of co-existing CCL and a lower number of ADH foci have a lower risk of disease upgrade at excision, and are potential candidates for observation-only management.

Diagnostic terminology used to describe atypia on breast core needle biopsy: correlation with excision and upgrade rates

Background

Subjective qualitative descriptors are sometimes used to describe atypical breast lesions diagnosed on core needle biopsy (CNB) which are limited in extent. In clinical practice, this terminology is used to imply a lower expected risk of upgrade on surgical excision (EXC). It is uncertain how subjective terminology impacts clinical management.

Methods

We conducted a retrospective review of CNB with atypia and compared the EXC and upgrade rates of atypical ductal hyperplasia (ADH) and flat epithelial atypia (FEA) to lesions described as “focal” atypical ductal hyperplasia (FADH), to determine the impact of this diagnostic phrasing on surgical management and risk of malignancy.

Results

FADH and ADH were excised at similar rates (82% vs. 78%). FADH lesions showed a similar upgrade rate (13%) compared to non-focal ADH (10%), and both showed a trend towards higher upgrade and EXC rates compared to FEA. ADH, FADH and FEA all had an upgrade risk that warranted EXC. In non-upgraded EXC, for each diagnostic category we observed similar rates of residual atypia in the EXC.

Conclusions

Pathologists should avoid the use of qualitative descriptors when describing ADH on CNB because of the potential of this terminology to influence clinical decision making which is unwarranted.

Core Needle Biopsy of the Breast: An Evaluation of Contemporary Data

Benign and atypical lesions associated with breast cancer risk are often encountered in core needle biopsies (CNBs) of the breast. For these lesions, the rate of "upgrade" to carcinoma in excision specimens varies widely in the literature. Many CNB studies are limited by a lack of radiological-pathological correlation, consistent criteria for excision, and clinical follow-up for patients who forego excision. This article highlights contemporary diagnostic criteria and outcome data that would support an evidence-based approach to the management of these nonmalignant lesions of the breast diagnosed on CNB.

Pathologic Upgrade Rates of High-Risk Breast Lesions on Digital Two-Dimensional vs Tomosynthesis Mammography

BACKGROUND

Our aim was to compare the pathologic upgrade rates of high-risk breast lesions (HRLs) on digital two-dimensional mammography (DM) vs digital breast tomosynthesis (DBT).

STUDY DESIGN

The study cohort was composed of patients with HRLs diagnosed by image-guided core needle biopsy from December 2007 to February 2011 (DM group, before DBT integration) and from January 2013 to March 2016 (DBT group, after complete DBT integration). Medical records were reviewed for surgical outcomes and follow-up imaging.

RESULTS

Eight hundred and ninety-three patients with 900 biopsy-proven HRLs underwent surgical excision (97.0% [873 of 900]) or had at least 2 years of imaging follow-up (3.0% [27 of 900]). The most common HRL was atypical ductal hyperplasia in the DM and DBT groups (37.4% [337 of 900]). The overall upgrade rate of HRLs to malignancy was 11.3% (102 of 900). There were no statistically significant differences in overall upgrades rates of HRLs on DM vs DBT (11.4% [54 of 475] vs 11.3% [48 of 425]; p = 0.97) or in upgrade rates of HRL subtypes. However, HRLs that upgraded on DBT were more likely to be invasive rather than in situ carcinoma compared with HRLs that upgraded on DM (39.6% [19 of 48] vs 20.4% [11 of 54]; p = 0.03). Overall, the most common HRL to upgrade was atypical ductal hyperplasia (18.4% [62 of 337]). The least common HRLs to upgrade in the DBT group were biphasic neoplasms (0% [0 of 22]), flat epithelial atypia (1.6% [1 of 62]), and papillomas without atypia (4.5% [2 of 44]).

CONCLUSIONS

There is no difference in the upgrade rates of HRLs on DM vs DBT, but the proportion of HRL upgrades that are invasive rather than in situ carcinoma is higher with DBT.

Current concepts in the diagnosis and pathobiology of intraepithelial neoplasia: A review by organ system

Answer questions and earn CME/CNE In this report, a team of surgical pathologists has provided a review of intraepithelial neoplasia in a host of (but not all) anatomic sites of interest to colleagues in various medical specialties, namely, uterine cervix, ovary, breast, lung, head and neck, skin, prostate, bladder, pancreas, and esophagus. There is more experience with more readily accessible sites (such as the uterine cervix and skin) than with other anatomic sites, and the lack of uniform terminology, together with divergent biology in various sites, makes it difficult to paint a unifying, relevant portrait. The authors' aim was to provide a framework from which to move forward as we care for patients with such precancerous lesions. CA Cancer J Clin 2016;66:408-436. © 2016 American Cancer Society.

Atypical Ductal Hyperplasia Bordering on Ductal Carcinoma In Situ

BACKGROUND

The clinical implications of the diagnosis of atypical ductal hyperplasia (ADH) and ductal carcinoma in situ (DCIS) are very different. Yet there are "borderline" breast lesions that have characteristics of both ADH and DCIS. We examined interobserver diagnostic variability for such lesions and correlated pathologic features of the lesions with clinical outcomes.

METHODS

We identified all cases of borderline ADH/DCIS lesions treated at our center from 1997 to 2010. Five specialized breast pathologists blinded to clinical outcomes independently reviewed all available slides from each case and were instructed to classify each as benign, ADH, or DCIS. A majority diagnosis (MajDx) was defined as a diagnosis agreed upon by ≥3 pathologists.

RESULTS

A total of 105 women with borderline ADH/DCIS and slides available for review were identified. The MajDx was ADH in 84 (80%), and DCIS in 18 (17%). There were split diagnoses in 3 (3%). MajDx of DCIS correlated significantly with lesion size and nuclear grade. There was diagnostic agreement by all 5 pathologists in 30% of cases, 4 pathologists in 42%, and 3 pathologists in 25%. At a median follow-up of 37 months, 4 (3.8%) patients developed subsequent ipsilateral breast carcinoma (2 invasive, 2 DCIS); all 4 cases had MajDx of ADH.

CONCLUSIONS

Borderline ADH/DCIS represents an entity for which reproducible categorization as ADH or DCIS cannot be achieved. Furthermore, histologic features of borderline lesions resulting in MajDx of ADH vs. DCIS are not prognostic for risk of subsequent breast carcinoma.

Practical Considerations in Breast Papillary Lesions: A Review of the Literature

Context.—Diagnosis of papillary breast lesions, especially in core biopsies, is challenging for most pathologists, and these lesions pose problems for patient management. Distinction between benign, premalignant, and malignant components of papillary lesions is challenging, and the diagnosis of invasion is problematic in lesions that have circumscribed margins. Obtaining a balance between overtreatment and undertreatment of these lesions is also challenging.

Objectives.—To provide a classification and a description of the histologic and immunohistochemical features and the differential diagnosis of papillary breast lesions, to provide an update on the molecular pathology of papillary breast lesions, and to discuss the recommendations for further investigation and management of papillary breast lesions. This review provides a concise description of the histologic and immunohistochemical features of the different papillary lesions of the breast.

Data Sources.—The standard pathology text books on breast pathology and literature on papillary breast lesions were reviewed with the assistance of the PubMed database (http://www.ncbi.nlm.nih.gov/pubmed).

Conclusions.—Knowledge of the clinical presentation, histology, immunoprofile, and behavior of papillary breast lesions will assist pathologists with the diagnosis and optimal management of patients with papillary breast lesions.

Examining the Relationship between Pre-Malignant Breast Lesions, Carcinogenesis and Tumor Evolution in the Mammary Epithelium Using an Agent-Based Model

INTRODUCTION

Breast cancer, the product of numerous rare mutational events that occur over an extended time period, presents numerous challenges to investigators interested in studying the transformation from normal breast epithelium to malignancy using traditional laboratory methods, particularly with respect to characterizing transitional and pre-malignant states. Dynamic computational modeling can provide insight into these pathophysiological dynamics, and as such we use a previously validated agent-based computational model of the mammary epithelium (the DEABM) to investigate the probabilistic mechanisms by which normal populations of ductal cells could transform into states replicating features of both pre-malignant breast lesions and a diverse set of breast cancer subtypes.

METHODS

The DEABM consists of simulated cellular populations governed by algorithms based on accepted and previously published cellular mechanisms. Cells respond to hormones, undergo mitosis, apoptosis and cellular differentiation. Heritable mutations to 12 genes prominently implicated in breast cancer are acquired via a probabilistic mechanism. 3000 simulations of the 40-year period of menstrual cycling were run in wild-type (WT) and BRCA1-mutated groups. Simulations were analyzed by development of hyperplastic states, incidence of malignancy, hormone receptor and HER-2 status, frequency of mutation to particular genes, and whether mutations were early events in carcinogenesis.

RESULTS

Cancer incidence in WT (2.6%) and BRCA1-mutated (45.9%) populations closely matched published epidemiologic rates. Hormone receptor expression profiles in both WT and BRCA groups also closely matched epidemiologic data. Hyperplastic populations carried more mutations than normal populations and mutations were similar to early mutations found in ER+ tumors (telomerase, E-cadherin, TGFB, RUNX3, p < .01). ER- tumors carried significantly more mutations and carried more early mutations in BRCA1, c-MYC and genes associated with epithelial-mesenchymal transition.

CONCLUSIONS

The DEABM generates diverse tumors that express tumor markers consistent with epidemiologic data. The DEABM also generates non-invasive, hyperplastic populations, analogous to atypia or ductal carcinoma in situ (DCIS), via mutations to genes known to be present in hyperplastic lesions and as early mutations in breast cancers. The results demonstrate that agent-based models are well-suited to studying tumor evolution through stages of carcinogenesis and have the potential to be used to develop prevention and treatment strategies.

Long term clinical follow-up of atypical ductal hyperplasia and lobular carcinoma in situ in breast core needle biopsies

Atypical ductal hyperplasia (ADH) and lobular carcinoma in situ (LCIS) may be associated with a relatively high incidence of invasive carcinoma and ductal carcinoma in situ (DCIS) on immediate excision when found on core needle biopsy of the breast. However, the long term significance of ADH and LCIS in a breast core needle biopsy is not as well characterised. We reviewed the results of all breast core needle biopsies with a diagnosis of ADH or LCIS and immediate excision from the years 2000-2004, and correlated the results with long term clinical follow-up. Of 175 biopsies with ADH, 53 (30.3%) had carcinoma (8 invasive, and 45 DCIS) at the time of immediate re-excision. Of 69 biopsies with LCIS, three (4.3%) had carcinoma (2 invasive, and 1 DCIS) at the time of immediate re-excision. A total of 14 (11.5%) patients with ADH and benign re-excisions developed invasive carcinoma (12) or DCIS (2) on follow-up. A total of 17 (25.8%) patients with LCIS and benign re-excisions developed invasive carcinoma (13) or DCIS (4) on follow-up. The risk of invasive carcinoma or DCIS on immediate re-excision was significantly higher for women with ADH than LCIS (p<0.001). Women with LCIS developed significantly more invasive carcinomas and DCIS than women with ADH on long term follow-up (p=0.01). Compared to women with fibrocystic changes (FCC) on core needle biopsy, the risk of developing invasive carcinoma or DCIS was significantly higher for women with ADH and benign initial re-excisions (95% CI 1.092-7.297, p=0.03), and women with LCIS and benign re-excisions (95% CI 3.028-18.657, p<0.001). Overall, 67/175 (38.3%) women with ADH and 20/69 (29.0%) women with LCIS on core needle biopsy either had carcinoma at the time of the biopsy or later developed carcinoma. Significantly more women with LCIS developed invasive carcinoma or DCIS than women with ADH on long term follow-up. The relative risk for ADH and LCIS on core biopsy with a negative excision compared with FCC was similar to that reported in the literature (ADH 1-7×, LCIS 3-19×).

Continued observation of the natural history of low-grade ductal carcinoma in situ reaffirms proclivity for local recurrence even after more than 30 years of follow-up

Opportunities to study the natural history of ductal carcinoma in situ are rare. A few studies of incompletely excised lesions in the premammographic era, retrospectively recognized as ductal carcinoma in situ, have demonstrated a proclivity for local recurrence in the original site. The authors report a follow-up study of 45 women with low-grade ductal carcinoma in situ treated by biopsy only, recognized retrospectively during a larger review of surgical pathology diagnoses and original histological slides for 26 539 consecutive breast biopsies performed at Vanderbilt, Baptist and St Thomas Hospitals in Nashville, TN from 1950 to 1989. Long-term follow-up was previously reported on 28 of these women. Sixteen women (36%) developed invasive breast carcinoma, all in the same breast and quadrant as their incident ductal carcinoma in situ. Eleven invasive breast carcinomas were diagnosed within 10 years of the ductal carcinoma in situ biopsy. Subsequent cases were diagnosed at 12, 23, 25, 29 and 42 years. Seven women, including one who developed invasive breast cancer 29 years after her ductal carcinoma in situ biopsy, developed distant metastasis, resulting in death 1-7 years postdiagnosis of invasive breast carcinoma. The natural history of low-grade ductal carcinoma in situ may extend more than four decades, with invasive breast cancer developing at the same site as the index lesion. This protracted natural history differs markedly from that of patients with high-grade ductal carcinoma in situ or any completely delimited ductal carcinoma in situ excised to negative margins. This study reaffirms the importance of complete margin evaluation in women treated with breast conservation for ductal carcinoma in situ as well as balancing recurrence risk with possible treatment-related morbidity for older women.

Current management of lesions associated with an increased risk of breast cancer

High-risk breast lesions, which comprise benign lesions and in situ carcinomas (lobular carcinoma in situ and ductal carcinoma in situ), are clinically, morphologically, and biologically heterogeneous and are associated with an increased risk of invasive breast cancer development, albeit to varying degrees. Recognition and proactive management of such lesions can help to prevent progression to invasive disease, and might, therefore, reduce breast cancer incidence, morbidity, and mortality. However, this opportunity comes with the possibility of overdiagnosis and overtreatment, necessitating risk-based intervention. Notably, despite the progress in defining the molecular changes associated with carcinogenesis, alterations identifying the individuals with high-risk lesions that will progress to invasive carcinoma remain to be identified. Thus, until reproducible clinicopathological or molecular features predicting an individual's risk of breast cancer are found, management strategies must be defined by population-level risks as determined by models such as the Gail or IBIS models, as well as patient attitudes toward the risks and benefits of interventions. Herein, we review the contemporary approaches to diagnosis and management of high-risk breast lesions. Progress in this area will ultimately be dependent on the ability to individualize risk prediction through better definition of the key drivers in the carcinogenic process.

Clinicopathologic features of ductal carcinoma in situ in young women with an emphasis on molecular subtype

Young women with ductal carcinoma in situ treated by breast-conserving therapy have a higher recurrence rate than do older women, and a younger age at diagnosis is associated with worse overall survival after recurrence. This study explores the clinical, pathologic, and immunohistochemical characteristics of ductal carcinoma in situ lesions diagnosed in women 40 years and younger with a focus on molecular subtypes to elucidate features that may contribute to the purported worse outcome for this patient population. Forty-one patients diagnosed with ductal carcinoma in situ at age 40 years and younger were identified over a 10-year period; 31 cases were used to construct tissue microarrays. The microarrays were labeled with antibodies to estrogen receptor, progesterone receptor, HER2, Ki-67, CK5/6, epidermal growth factor receptor, and p53 and subsequently classified as luminal A, luminal B, HER2, basal-like, or unclassifiable triple negative. All patients had high-grade (73.2%) or intermediate-grade (26.8%) ductal carcinoma in situ. The molecular subtype breakdown was 61.3% luminal A, 22.6% luminal B, 13% HER2, and 3.1% unclassifiable triple negative. The mean Ki-67 by subtype was 4.2%, 14%, 9.5%, and 50%, respectively. Mastectomy was performed in 33 patients (80%). Eight patients (20%) underwent excisional biopsy without subsequent mastectomy. In addition to a predominance of high-grade lesions, young patients had a high proportion of luminal B subtype, which may contribute to an increased rate of local recurrence in this population. A larger series is necessary to confirm the impact that the molecular subtypes of ductal carcinoma in situ in younger patients might have on outcome.