Pattern and spectrum of morphology referrals in breast pathology consultation

Pitfalls and controversies in pathology impacting breast cancer management

Introduction: Breast cancer is a heterogeneous disease, at morphological, molecular, and clinical levels and this has significant implications for the diagnosis and management of the disease. The introduction of breast screening, and the use of small tissue sampling for diagnosis, the recognition of new morphological and molecular subtypes, and the increasing use of neoadjuvant therapies have created challenges in pathological diagnosis and classification.Areas covered: Areas of potential difficulty include columnar cell lesions, particularly flat epithelial atypia, atypical ductal hyperplasia, lobular neoplasia and its variants, and a range of papillary lesions. Fibroepithelial, sclerosing, mucinous, and apocrine lesions are also considered. Established and newer prognostic and predictive markers, such as immune infiltrates, PD-1 and PD-L1 and gene expression assays are evaluated. The unique challenges of pathology assessment post-neoadjuvant systemic therapy are also explored.Expert opinion: Controversies in clinical management arise due to incomplete and sometimes conflicting data on clinicopathological associations, prognosis, and outcome. The review will address some of these challenges.

Histological features associated with diagnostic agreement in atypical ductal hyperplasia of the breast: illustrative cases from the B-Path study

AIMS

This study examined the case-specific characteristics associated with interobserver diagnostic agreement in atypical ductal hyperplasia (ADH) of the breast.

METHODS AND RESULTS

Seventy-two test set cases with a consensus diagnosis of ADH from the B-Path study were evaluated. Cases were scored for 17 histological features, which were then correlated with the participant agreement with the consensus ADH diagnosis. Participating pathologists' perceptions of case difficulty, borderline features or whether they would obtain a second opinion were also examined for associations with agreement. Of the 2070 participant interpretations of the 72 consensus ADH cases, 48% were scored by participants as difficult and 45% as borderline between two diagnoses; the presence of both of these features was significantly associated with increased agreement (P < 0.001). A second opinion would have been obtained in 80% of interpretations, and this was associated with increased agreement (P < 0.001). Diagnostic agreement ranged from 10% to 89% on a case-by-case basis. Cases with papillary lesions, cribriform architecture and obvious cytological monotony were associated with higher agreement. Lower agreement rates were associated with solid or micropapillary architecture, borderline cytological monotony, or cases without a diagnostic area that was obvious on low power.

CONCLUSIONS

The results of this study suggest that pathologists frequently recognize the challenge of ADH cases, with some cases being more prone to diagnostic variability. In addition, there are specific histological features associated with diagnostic agreement on ADH cases. Multiple example images from cases in this test set are provided to serve as educational illustrations of these challenges.

Changes in breast cancer reports after pathology second opinion

Breast cancer pathology reports contain valuable information about the histologic diagnosis, prognostic factors and predictive indicators of therapeutic response. A second opinion may be requested by medical oncologists and surgeons, when a patient is referred from another institution for treatment. We report the experience with pathology second opinion in selected patients referred to the Breast Oncology Unit. 205 cases referred to the Breast Oncology Unit were selected for second opinion after clinical evaluation, between 2002 and 2012. The cases reviewed included 102 core needle biopsies, 88 surgical specimens from the breast and 18 lymphadenopathies, 14 from the axillary region. Pathology second opinion was based on a review of hematoxylin-eosin preparations, recuts of submitted paraffin blocks and written external pathology reports. Immunohistochemical studies for hormone receptors, HER2, myoepithelial cells, and other markers were performed in selected cases. A case was reclassified as showing major change when second opinion showed a potential for significant change in prognosis or treatment. Otherwise, it was considered to represent minor change or to be concordant. In 52 cases (25.4%), the pathology review showed changes. Thirty-three (16%) patients were reclassified for major changes and 19 (9.2%) as minor changes. In six patients, more than one major change was identified. The major discrepancies identified were related to the histologic classification (12 cases), the presence or absence of invasion in ductal carcinoma (15 cases), the results of hormone receptors (5 cases), and HER2 (7 cases). Major changes in histologic classification included two cases diagnosed as invasive ductal carcinoma and reclassified as benign, four cases with diagnosis of breast cancer reclassified as metastatic lung cancer, one case diagnosed as small cell carcinoma of lung metastatic in the breast, reclassified as primary carcinoma of the breast, and three cases with diagnosis of breast cancer in the axilla reclassified as primary cutaneous adnexal carcinomas (2) and metastatic melanoma (1), respectively. In two cases, the histologic type of the primary breast tumor was changed. Second opinion in breast pathology may uncover significant discrepancies that impact on patient management and prognosis. Major discrepancies are most frequently related to the assessment of the presence or absence of invasion in ductal carcinoma, the results of predictive makers of therapeutic response, and the differential diagnosis of breast cancer and nonmammary tumors in the breast, the axilla, and at distant sites.

Clinical examination and validation of primary diagnosis in anatomic pathology using whole slide digital images

CONTEXT

Novel anatomic pathology technologies allow pathologists to digitally view and diagnose cases. Although digital pathology advocates champion its strengths and move to integrate it into practice and workflow, the capabilities and limitations of digital slides have not been fully investigated.

OBJECTIVES

To estimate intrapathologist diagnostic discrepancy between glass and digital slides and to determine pathologists' diagnostic certainty when diagnosing with the 2 formats.

DESIGN

Intrapathologist diagnostic consistency between glass and digital slides was measured. Three pathologists diagnosed 101 cases digitally and with corresponding glass slides. Discrepancies between formats were evaluated, and diagnostic precision and certainty were compared.

RESULTS

A total of 606 diagnoses were evaluated in pairs (202 per pathologist). Seven cases did not transfer to the database and were eliminated from further study. We report no discrepancies between media in 75%, 87%, and 83% of the cases diagnosed by the 3 pathologists, respectively; significant discrepancies were identified in 3%, 3%, and 7% of cases by each pathologist. In total, we identified significant clinical and therapeutic discrepancies in 13 of 296 cases (4.4%). The certainty values provided by each pathologist were similar between formats.

CONCLUSIONS

This study did not detect significant differences between diagnoses based on digital and glass slides. We believe that this study further supports the integration of digital slides into pathology workflow, particularly considering the low rate of discrepancy documented here.