Screen-detected breast lesions with malignant needle core biopsy diagnoses and no malignancy identified in subsequent surgical excision specimens (potential false-positive diagnosis)

Changes in the Diagnoses of Breast Core Needle Biopsies on Second Review at a Tertiary Care Center: Implications for Surgical Management

Core needle biopsy (CNB) of breast lesions is routine for diagnosis and treatment planning. Despite refinement of diagnostic criteria, the diagnosis of breast lesions on CNB can be challenging. At many centers, including ours, confirmation of diagnoses rendered in other laboratories is required before treatment planning. We identified CNBs first diagnosed elsewhere that were reviewed in our department over the course of 1 year because the patients sought care at our center and in which a change in diagnosis had been recorded. The outside and in-house CNB diagnoses were then classified based on Breast WHO Fifth Edition diagnostic categories. The impact of the change in diagnosis was estimated based on the subsequent surgical management. Findings in follow-up surgical excisions (EXCs) were used for validation. In 2018, 4950 outside cases with CNB were reviewed at our center. A total of 403 CNBs diagnoses were discrepant. Of these, 147 had a change in the WHO diagnostic category: 80 (54%) CNBs had a more severe diagnosis and 44 (30%) a less severe diagnosis. In 23 (16%) CNBs, the change of diagnostic category had no impact on management. Intraductal proliferations (n=54), microinvasive carcinoma (n=18), and papillary lesions (n=35) were the most disputed diagnoses. The in-house CNB diagnosis was confirmed in most cases with available excisions. Following CNB reclassification, 22/147 (15%) lesions were not excised. A change affecting the surgical management at our center occurred in 2.5% of all CNBs. Our results support routine review of outside breast CNB as a clinically significant practice before definitive treatment.

Pitfalls in breast pathology

Accurate pathological diagnosis is the cornerstone of optimal clinical management for patients with breast disease. As non-operative diagnosis has now become the standard of care, histopathologists encounter the daily challenge of making definitive diagnoses on limited breast core needle biopsy (CNB) material. CNB samples are carefully evaluated using microscopic examination of haematoxylin and eosin (H&E)-stained slides and supportive immunohistochemistry (IHC), providing the necessary information to inform the next steps in the patient care pathway. Some entities may be difficult to distinguish on small tissue samples, and if there is uncertainty a diagnostic excision biopsy should be recommended. This review discusses (1) benign breast lesions that may mimic malignancy, (2) malignant conditions that may be misinterpreted as benign, (3) malignant conditions that may be incorrectly diagnosed as primary breast carcinoma, and (4) some IHC pitfalls. The aim of the review is to raise awareness of potential pitfalls in the interpretation of breast lesions that may lead to underdiagnosis, overdiagnosis, or incorrect classification of malignancy with potential adverse outcomes for individual patients.

Tumor Size in Breast Carcinoma: Gross Measurement Is Important!

Introduction. The staging of breast carcinoma is mainly dependent on tumor size and lymph node status. Small increments in tumor size upstage the patient. An accurate determination of the tumor size is therefore critically important. Although the final staging is based on microscopic size, pathologists rely on gross measurements in a considerable number of cases. Methods. We investigated the concordance between gross and microscopic measurements of breast carcinoma as well as factors affecting this concordance. This study is a retrospective review of surgical pathology reports of invasive breast carcinomas. Data were collected for 411 cases. Concordance was defined as a size difference within ±2 mm. Results. Gross and microscopic sizes were identical in 33.1% of cases. Gross and microscopic size difference was within ±2 mm in 56% of cases. Despite the size difference, stage classification ended up being the same in 68.6% of cases. Tumor stage was over estimated by gross measurement in 17.0% of cases and underestimated in 14.4% of cases. The concordance was significantly higher for those tumors in which final pathologic tumor (pT) size was greater than 2 cm (≥pT2) as compared with those less than or equal to 2 cm (≤pT1; P < .0001). A higher proportion of mastectomy specimens (61.4%) were concordant as compared with lumpectomy specimens (52.1%). Conclusion. Gross and microscopic tumor sizes were concordant in 56% of cases. Stage classification based on gross and microscopic tumor size was different in nearly one third (31.4%) of cases. Gross tumor size is critically important in accurate staging at least in cases where tumor size cannot be confirmed microscopically.

Estimate of false-positive breast cancer diagnoses from accuracy studies: a systematic review

Background

False-positive histological diagnoses have the same consequences of overdiagnosis in terms of unnecessary treatment. The aim of this systematic review is to assess their frequency at needle core biopsy (CB) and/or surgical excision of the breast.

Methods

PubMed, Embase, Cochrane Library were systematically searched up to 30 October 2015. Eligibility criteria: cross-sectional studies assessing diagnostic accuracy of CB compared with surgical excision; studies assessing reproducibility of pathologists reading the same slides. Outcomes: false-positive rates; Misclassification of Benign as Malignant (MBM) histological diagnosis; K statistic. Independent reviewers extracted data and assessed quality using an adapted QUADAS-2 tool.

Results

Sixteen studies assessed CB false-positive rates. In 10 studies (41 989 screen-detected lesions), the range of false-positive rates was 0%–7.1%. Twenty-seven studies assessed pathologists' reproducibility. Studies with consecutive, random or stratified samples of all the specimens: at CB the MBM range was 0.25%–2.4% (K values 0.83–0.98); at surgical excision, it was 0.67%–1.2% (K values 0.86–0.94). Studies with enriched samples: the MBM range was 1.4%–6.2% (K values 0.57–0.86). Studies of cases selected for second opinion: the MBM range was 0.29%–12.2% (K values 0.48 and 0.50).

Conclusions

High heterogeneity of the included studies precluded formal pooling estimates. When considering studies of higher sample size or methodological quality, false-positive rates and MBM are around 1%. The impact of false-positive histological diagnoses of breast cancer on unnecessary treatment, as well as that of overdiagnosis, is not negligible and is of importance in clinical practice.

Effectiveness of core biopsy for screen-detected breast lesions under 10 mm: implications for surgical management

BACKGROUND

Technical advances have improved the detection of small mammographic lesions. In the context of mammographic screening, accurate sampling of these lesions by percutaneous biopsy is crucial in limiting diagnostic surgical biopsies, many of which show benign results.

METHODS

Women undergoing core biopsy between January 1997 and December 2007 for <10-mm lesions are included. Patient demographics, imaging features and final histology were tabulated. Performance indices were evaluated.

RESULTS

This audit includes 803 lesions <10 mm. Based on core histology, 345 women (43.0%) were immediately cleared of malignancy and 300 (37.4%) were referred for definitive cancer treatment. A further 157 women (19.6%) required diagnostic surgical biopsy because of indefinite or inadequate core results or radiological-pathological discordance, and one woman (0.1%) needed further imaging in 12 months. The open biopsies were malignant in 46 (29.3%) cases. The positive predictive value of malignant core biopsy was 100%. The negative predictive value for benign core results was 97.7%, and the false-negative rate was 2.6%. The lesion could not be visualized after core biopsy in 5.1% of women and in 4.0% of women with malignant core biopsies excision specimens did not contain residual malignancy. Excessive delays in surgery because of complications of core biopsy were not reported.

CONCLUSION

Even at this small size range, core biopsy evaluation of screen-detected breast lesions is highly effective and accurate. A lesion miss rate of 3.1% and under-representation of lesions on core samples highlight the continued need for multidisciplinary collaboration and selective use of diagnostic surgical biopsy.

Complexities and challenges in the pathologic assessment of size (T) of invasive breast carcinoma

Size (the "T" in the TNM System) of invasive breast carcinoma is a proven independent prognostic factor; however, its accurate determination can be challenging. The purpose of this review is to discuss the complexities inherent in determining "T"-including those encountered in the clinical measurement ("cT", ie, physical and radiologic assessment) as well as pathologic determination (pT) of invasive breast carcinomas. Pathologic estimation of tumor size, macroscopic, as well as microscopic, can be problematic due to the complexity of multiple situations, seeming confusion regarding staging guidelines, and interobserver variation in interpretation. Additional problematic scenarios in determination of "T" include those incurred in excisions performed after the performance of needle core biopsies, and in cases wherein there are multiple foci of invasive carcinoma, as well as in carcinomas status post-neoadjuvant chemotherapy. It can also be difficult to determine "T" in certain types of invasive carcinoma, particularly those of the lobular type. In this communication, some of the complexities and challenges in determing "T" are discussed, and modest suggestions are offered to assist in optimizing such assessments.

Screen-detected malignant breast lesions diagnosed following benign (B2) or normal (B1) needle core biopsy diagnoses

Breast needle core biopsy (NCB) is now a standard diagnostic procedure in the triple assessment of screen detected breast lesions. However, unlike fine needle aspiration (FNA) cytology, information on the miss rate including false-negative diagnoses (FN) of malignancy (benign 'B2' or normal 'B1' NCB with a malignant outcome) is limited.

METHODS

A large series of NCBs (121,742) performed over an 8-year period has been studied to assess the frequency and causes of missing a malignant diagnosis on NCB and to evaluate their impact on patients' management in the screening service.

RESULTS

During the period of this study, 50,691 were diagnosed as B2 and 9599 were diagnosed as B1. Of those, 779 B2 and 919 B1 were diagnosed as malignant on the subsequent surgical specimens, respectively, giving a FN rate of 3.0%. However when year of diagnosis was taken into consideration, we found that during the period 1999-2001, the FN rate for B2 was 2.7% while the miss rate for B1 was 4.0%. This showed marked improvement over time to reach a figure of 0.5% and 0.5% for B2 and B1, respectively, during the period 2005-2007. On detailed review of cases from a single screening region diagnosed during the last 3 years (2005-2008), 14 cases (0.17% of all NCBs) with malignant surgery were diagnosed as B2 (seven cases; FN rate 0.19%) and B1 (seven cases; B1 biopsy rate from cancer 0.19%). In these cases, NCB was unsatisfactory, there was a discrepancy between radiological abnormalities and histological findings with recommendation for excision or suspicious/malignant cytological diagnosis on concurrent FNA material. Therefore, our results indicate that the malignancy miss rate on NCB is rare and FN NCB diagnoses had no impact on patient management.

High and intermediate grade ductal carcinoma in-situ of the breast: a comparison of pathologic features in core biopsies and excisions and an evaluation of core biopsy features that may predict a close or positive margin in the excision

Low and high-grade ductal carcinoma in-situ (DCIS) are known to be highly disparate by a multitude of parameters, including progression potential, immunophenotype, gene expression profile and DNA ploidy. In this study, we analyzed a group of intermediate and high-grade DCIS cases to determine how well the core biopsy predicts the maximal pathology in the associated excisions, and to determine if there are any core biopsy morphologic features that may predict a close (≤ 0.2 cm) or positive margin in the subsequent excision. Forty-nine consecutive paired specimens [core biopsies with a maximal diagnosis of DCIS, and their corresponding excisions, which included 20 and 29 specimens from mastectomies and breast conserving surgeries respectively] were evaluated in detail. In 5 (10%) of 49 cases, no residual carcinoma was found in the excision. In another 4 cases, the changes were diagnostic only of atypical ductal hyperplasia. There were 4 and 3 respective cases of invasive and microinvasive carcinoma out of the 49 excision specimens, for an overall invasion frequency of 14%. In 28 cases where a sentinel lymph node evaluation was performed, only 1 was found to be positive. Among the 40 cases with at least residual DCIS in the excision, there were 5 cases in which comedo-pattern DCIS was present in the excision but not in the core biopsy, attributed to the lower maximal nuclear grade in the biopsy proliferation in 4 cases and the absence of central necrosis in the 5^th. For the other main histologic patterns, in 8 (20%) of 40 cases, there were more patterns identified in the core biopsy than in the corresponding excision. For the other 32 cases, 100%, 66%, 50%, 33% and 25% of the number of histologic patterns in the excisions were captured in 35%, 5%, 17.5%, 15% and 7.5% of the preceding core biopsies respectively. Therefore, the core biopsy reflected at least half of the non-comedo histologic patterns in 77.5% of cases. In 6(15%) of the 40 cases, the maximum nuclear grade of the excision (grade 3) was higher than that seen in the core biopsy (grade 2). Overall, however, the maximum nuclear grade in the excision was significantly predicted by maximum nuclear grade in the core biopsy (p = 0.028), with a Phi of 0.347, indicating a moderately strong association. At a size threshold of 2.7 cm, there was no significant association between lesional size and core biopsy features. Furthermore, the clear margin width of the cases with lesional size ≤ 2.7 cm (mean 0.69 cm) was not significantly different (p = 0.4) from the cases with lesional size > 2.7 cm (mean 0.56 cm). Finally, among a variety of core biopsy features that were evaluated, including maximum nuclear grade, necrosis, cancerization of lobules, number of tissue cores with DCIS, number of DCIS ducts per tissue core, total DCIS ducts, or comedo-pattern, only necrosis was significantly associated with a positive or close (≤ 0.2 cm) margin on multivariate analysis (Phi of 0.350). It is concluded that a significant change [to invasive disease (14%) or to no residual disease (10%)] is seen in approximately 24% of excisions that follow a core biopsy diagnosis of intermediate or high-grade DCIS. Core biopsy features are of limited value in predicting a close or positive margin in these lesions.