Diffusion tensor imaging for characterizing tumor microstructure and improving diagnostic performance on breast MRI: a prospective observational study.

BACKGROUND: Diffusion-weighted imaging (DWI) can increase breast MRI diagnostic specificity due to the tendency of malignancies to restrict diffusion. Diffusion tensor imaging (DTI) provides further information over conventional DWI regarding diffusion directionality and anisotropy. Our study evaluates DTI features of suspicious breast lesions detected on MRI to determine the added diagnostic value of DTI for breast imaging. METHODS: With IRB approval, we prospectively enrolled patients over a 3-year period who had suspicious (BI-RADS category 4 or 5) MRI-detected breast lesions with histopathological results. Patients underwent multiparametric 3 T MRI with dynamic contrast-enhanced (DCE) and DTI sequences. Clinical factors (age, menopausal status, breast density, clinical indication, background parenchymal enhancement) and DCE-MRI lesion parameters (size, type, presence of washout, BI-RADS category) were recorded prospectively by interpreting radiologists. DTI parameters (apparent diffusion coefficient [ADC], fractional anisotropy [FA], axial diffusivity [λ1], radial diffusivity [(λ2 + λ3)/2], and empirical difference [λ1 - λ3]) were measured retrospectively. Generalized estimating equations (GEE) and least absolute shrinkage and selection operator (LASSO) methods were used for univariate and multivariate logistic regression, respectively. Diagnostic performance was internally validated using the area under the curve (AUC) with bootstrap adjustment. RESULTS: The study included 238 suspicious breast lesions (95 malignant, 143 benign) in 194 women. In univariate analysis, lower ADC, axial diffusivity, and radial diffusivity were associated with malignancy (OR = 0.37-0.42 per 1-SD increase, p < 0.001 for each), as was higher FA (OR = 1.45, p = 0.007). In multivariate analysis, LASSO selected only ADC (OR = 0.41) as a predictor for a DTI-only model, while both ADC (OR = 0.41) and FA (OR = 0.88) were selected for a model combining clinical and imaging parameters. Post-hoc analysis revealed varying association of FA with malignancy depending on the lesion type. The combined model (AUC = 0.81) had a significantly better performance than Clinical/DCE-MRI-only (AUC = 0.76, p < 0.001) and DTI-only (AUC = 0.75, p = 0.002) models. CONCLUSIONS: DTI significantly improves diagnostic performance in multivariate modeling. ADC is the most important diffusion parameter for distinguishing benign and malignant breast lesions, while anisotropy measures may help further characterize tumor microstructure and microenvironment.

Diffusion-weighted MRI characteristics associated with prognostic pathological factors and recurrence risk in invasive ER+/HER2- breast cancers.

BACKGROUND: Hormone receptor-positive breast cancer is the most common subtype; better tools to identify which patients in this group would derive clear benefit from chemotherapy are needed. PURPOSE: To evaluate the prognostic potential of diffusion-weighted MRI (DWI) by investigating associations with pathologic biomarkers and a genomic assay for 10-year recurrence risk. STUDY TYPE: Retrospective. SUBJECTS: In all, 107 consecutive patients (from 2/2010 to 1/2013) with estrogen receptor (ER)-positive/HER2neu-negative invasive breast cancer who had the 21-gene recurrence score (RS) test (Oncotype DX, Genomic Health). FIELD STRENGTH/SEQUENCE: Each subject underwent presurgical 3T breast MRI, which included DWI (b = 0, 800 s/mm2 ). ASSESSMENT: Apparent diffusion coefficient (ADC) and contrast-to-noise ratio (CNR) were measured for each lesion by a fifth year radiology resident. Pathological markers (Nottingham histologic grade, Ki-67, RS) were determined from pathology reports. Medical records were reviewed to assess recurrence-free survival. STATISTICAL TESTS: RS was stratified into low (<18), moderate (18-30), and high (>30)-risk groups. Associations of DWI characteristics with pathologic biomarkers were evaluated by binary or ordinal logistic regression, as appropriate, with adjustment for multiple comparisons. Post-hoc comparisons between specific groups were also performed. RESULTS: ADCmean (odds ratio [OR] = 0.61 per 1 standard deviation [SD] increase, adj. P = 0.044) and CNR (OR = 1.76 per 1-SD increase, adj. P = 0.026) were significantly associated with increasing tumor grade. DWI CNR was also significantly associated with a high (Ki-67 ≥14%) proliferation rate (OR = 2.55 per 1-SD increase, adj. P = 0.026). While there were no statistically significant linear associations in ADC (adj. P = 0.80-0.85) and CNR (adj. P = 0.56) across all three RS groups by ordinal logistic regression, post-hoc analyses suggested that high RS lesions exhibited lower ADCmean (P = 0.037) and ADCmax (P = 0.004) values and higher CNR (P = 0.008) compared to lesions with a low or moderate RS. DATA CONCLUSION: DWI characteristics correlated with tumor grade, proliferation index, and RS, and may potentially help to identify those with highest recurrence risk and most potential benefit from chemotherapy. LEVEL OF EVIDENCE: 3 Technical Efficacy Stage 3 J. Magn. Reson. Imaging 2017.

Evaluation of Intraoperative Assessments in the Management of Endometrial Carcinoma: A Retrospective Quality Assurance Review.

Intraoperative assessment (IA) of uteri is often used to help determine whether to perform lymphadenectomy in patients with endometrial carcinoma. We sought to perform a quality assurance review of the practice of IA at our institution. In a 1-yr period, 107 hysterectomies had an IA performed. Grade of neoplasm in preoperative endometrial biopsy, neoplasm size, depth of myometrial invasion at IA, operative management, and final histologic features were recorded. Operative reports were reviewed to assess the surgeon's interpretation of the IA and the effect on surgical management. The sensitivity and specificity for IA of deep myometrial invasion (>50% myometrial thickness) compared with final histology was 76.9% and 91.1%. The positive predictive value was 71.4%, negative predictive value 93.2% and accuracy 88%. Neoplasm size was provided in 47% of cases. In 10% of patients lymphadenectomy was performed despite low-risk features. IA results were included in the operative report in 87% of cases. There were differences in 8.4% of cases between the IA diagnosis and the surgeon's operative report. IA of deep myometrial invasion is reliable at our institution. Several metrics for quality improvement have been identified as a result of this retrospective review. These include but are not limited to more reliable reporting of neoplasm size, documentation, and communication with gynecologic oncologists.

'Non-classical' HER2 FISH results in breast cancer: a multi-institutional study.

The 2013 CAP/ASCO HER2 Testing Guidelines Update modified HER2 FISH categories such that some cases with 'monosomy', 'co-amplification/polysomy', low-level increased HER2 signals or clustered heterogeneity now are considered amplified or equivocal. This study examines the frequency and clinico-pathologic characteristics of breast cancers with equivocal or 'non-classical' HER2 FISH results. Breast cancers (2001-2014) with HER2 FISH results, HER2 immunohistochemistry, ER, grade, and age from three institutions (Stanford, UCSF, UWMC) were collected. HER2 FISH was interpreted using the updated recommendations. Amplified cases with non-classical results were grouped into the following categories: (1) 'monosomy' (ratio ≥2.0, mean HER2/cell<4.0); (2) 'co-amplified' (ratio<2.0, mean HER2/cell ≥6.0); (3) 'low amplified' (ratio ≥2.0, mean HER2/cell 4.0-5.9). Heterogeneous cases with clustered HER2-positive cells were also included. Of 8068 cases, 5.2% were equivocal and 4.6% had a 'non-classical' HER2 amplified result; 1.4% 'monosomy', 0.8% 'co-amplified', 2.1% 'low amplified', and 0.3% clustered heterogeneity. These cancers had a high frequency of ER positive (80.4%), Nottingham grade 3 (52.1%) results. The highest percentage of grade 3 cancers (66.7%) and positive HER2 immunohistochemistry (31.7%) was in the 'co-amplified' group. The 'monosomy' group had the highest percent grade 1 cancers (13.3%) and was most frequently HER2 immunohistochemistry negative (30.1%). Equivocal cases had very similar characteristics to the 'low-amplified' category. Cases with non-classical HER2 amplification or equivocal results are typically ER positive, higher grade cancers. 'Co-amplified' cases have the highest frequencies of aggressive characteristics and 'monosomy' cases the highest frequencies of lower risk features. With little clinical outcomes data currently available on these non-classical HER2 results, these results support the current classification scheme for HER2 FISH, with case-by-case correlation with additional clinical-pathologic factors when evaluating whether to offer HER2-targeted therapies in these non-classical cases.

Apparent diffusion coefficient values may help predict which MRI-detected high-risk breast lesions will upgrade at surgical excision.

PURPOSE: To investigate whether diffusion-weighted imaging (DWI) features could assist in determining which high-risk lesions identified on dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and diagnosed on core needle biopsy (CNB) will upgrade to malignancy on surgical excision. MATERIALS AND METHODS: This Institutional Review Board (IRB)-approved prospective study included participants with MRI-detected Breast Imaging Reporting and Data System (BI-RADS) 4 or 5 lesions with high-risk pathology on CNB who underwent surgical excision. Twenty-three high-risk lesions detected on 3T breast MRI in 20 women (average age = 54 ± 9 years) were evaluated, of which six lesions (26%) upgraded to malignancy at surgery. DCE, DWI characteristics, and clinical factors were compared between high-risk lesions that upgraded to malignancy on surgical excision and those that did not. Logistic regression modeling was performed to identify features that optimally predicted upgrade to malignancy, with performance described using area under the receiver operating characteristic curve (AUC). RESULTS: High-risk lesions that upgraded on excision demonstrated lower apparent diffusion coefficient (ADC) than those that did not (median, 1.08 × 10-3 mm2 /s vs.1.39 × 10-3 mm2 /s, P = 0.046), and a trend of greater maximum lesion size (median, 24 mm vs. 8 mm, P = 0.053). There were no significant differences in lesion type (mass vs. nonmass enhancement, P = 1.0) or kinetic features (P = 0.78 for peak initial enhancement; P = 1.0 for worst curve type) among the high-risk cohorts. A model incorporating maximum lesion size and ADC provided optimal performance to predict upgrade to malignancy (AUC = 0.89). CONCLUSION: ADC and maximum lesion size on MRI show promise for predicting which MRI-detected high-risk lesions will upgrade to malignancy at surgical excision. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:1028-1036.

Region of interest identification and diagnostic agreement in breast pathology.

A pathologist's accurate interpretation relies on identifying relevant histopathological features. Little is known about the precise relationship between feature identification and diagnostic decision making. We hypothesized that greater overlap between a pathologist's selected diagnostic region of interest (ROI) and a consensus derived ROI is associated with higher diagnostic accuracy. We developed breast biopsy test cases that included atypical ductal hyperplasia (n=80); ductal carcinoma in situ (n=78); and invasive breast cancer (n=22). Benign cases were excluded due to the absence of specific abnormalities. Three experienced breast pathologists conducted an independent review of the 180 digital whole slide images, established a reference consensus diagnosis and marked one or more diagnostic ROIs for each case. Forty-four participating pathologists independently diagnosed and marked ROIs on the images. Participant diagnoses and ROI were compared with consensus reference diagnoses and ROI. Regression models tested whether percent overlap between participant ROI and consensus reference ROI predicted diagnostic accuracy. Each of the 44 participants interpreted 39-50 cases for a total of 1972 individual diagnoses. Percent ROI overlap with the expert reference ROI was higher in pathologists who self-reported academic affiliation (69 vs 65%, P=0.002). Percent overlap between participants' ROI and consensus reference ROI was then classified into ordinal categories: 0, 1-33, 34-65, 66-99 and 100% overlap. For each incremental change in the ordinal percent ROI overlap, diagnostic agreement increased by 60% (OR 1.6, 95% CI (1.5-1.7), P<0.001) and the association remained significant even after adjustment for other covariates. The magnitude of the association between ROI overlap and diagnostic agreement increased with increasing diagnostic severity. The findings indicate that pathologists are more likely to converge with an expert reference diagnosis when they identify an overlapping diagnostic image region, suggesting that future computer-aided detection systems that highlight potential diagnostic regions could be a helpful tool to improve accuracy and education.

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.

Adjuvant Endocrine Therapy in Patients with Ductal Carcinoma In Situ: A Population-Based Retrospective Analysis from 2005 to 2012 in the National Cancer Data Base.

BACKGROUND: Adjuvant endocrine therapy (AET) has been shown to reduce the risk of second breast cancer events in women with ductal carcinoma in situ (DCIS). There is no population-level evaluation of AET use in DCIS patients after standardized reporting of estrogen receptor (ER) status in cancer registries in 2004. METHODS: We conducted a retrospective cohort study of women with DCIS in the National Cancer Data Base between 2005 and 2012. Patient, tumor, and treatment characteristics as well as temporal trends associated with receipt of AET were evaluated by generalized linear regression. RESULTS: Among 206,255 DCIS patients, 36.5% received AET. Fewer than half of ER-positive patients (n = 62,146, 46.4%) received AET, with a modest but significant increase over time (43.6% in 2005 to 47.5% in 2012; unadjusted p trend <0.001). AET decreased among ER-negative patients (8.9-6.5%, p trend <0.001) over the same time period. On multivariate analysis, younger (<40 years) and older (≥70 years) women were less likely to receive AET than 50- to 59-year-old women (<40 years: relative risk 0.86, 95% confidence interval 0.82-0.89; ≥70 years: relative risk 0.79, 95% confidence interval 0.77-0.81). ER-positive status conferred a 6.15-fold higher likelihood of receiving AET compared to ER-negative status (95% confidence interval 5.81-6.50). Women who underwent breast-conserving surgery (BCS) with adjuvant radiotherapy were most likely to receive AET. CONCLUSIONS: Receipt of AET is relatively low in the group of women most likely to benefit from its use, namely ER-positive patients who underwent BCS. Significant variation exists with respect to patient, tumor, site, and treatment factors. More tolerable drugs or clearer guideline recommendations may increase use.

Pleomorphic Lobular Carcinoma In Situ: Radiologic-Pathologic Features and Clinical Management.

BACKGROUND: Pleomorphic lobular carcinoma in situ (PLCIS) is an unusual variant of LCIS for which optimal management remains unclear. METHODS: We conducted a 15-year (2000-2014) retrospective chart review of the radiologic, pathologic, clinical management, and recurrence rates of patients with PLCIS on diagnostic biopsy. Fifty-one patients were found to have PLCIS either alone or with concomitant breast cancer. Of these, 23 were found to have pure PLCIS on diagnostic biopsy. Rates of upstaging after local excision, positive or close margins, mastectomy, and recurrence associated with pure pleomorphic lobular carcinoma in situ were examined. RESULTS: Of the 21 patients who underwent surgical excision following diagnostic biopsy, 33.3 % (7/21) were found to have invasive carcinoma, and 19 % (4/23) were found to have ductal carcinoma in situ. Extensive or multifocal PLCIS was present in 47.6 % (10/21) of patients, corresponding to at least one PLCIS-positive or close margin in 71.4 % (15/21). In total, there were 11 local re-excisions in nine patients, and 12 mastectomies. No ipsilateral breast cancer events have occurred, including in those with positive or close surgical margins (mean follow-up 4.1 years). CONCLUSIONS: Patients with isolated PLCIS on diagnostic biopsy are at high risk of upgrading to invasive cancer or ductal carcinoma in situ at diagnostic excision. PLCIS often is extensive, with high rates of positive or close surgical resection margins. If negative PLCIS margins are pursued, rates of successful breast conservation are low. In light of this and low recurrence rates, caution should be exercised in aggressively treating PLCIS with excision to clear margins.

Lobular in-situ neoplasia on breast core needle biopsy: imaging indication and pathologic extent can identify which patients require excisional biopsy.

BACKGROUND: The surgical management of lobular in-situ neoplasia (LN) identified by core needle biopsy (CNB) is currently variable. Our institution has routinely excised LN on CNB since 2003, allowing for an unbiased assessment of upgrade rates. METHODS: Cases of LN on CNB, including atypical lobular hyperplasia (ALH) and lobular carcinoma-in-situ (LCIS), were identified in our pathology database. CNBs with concurrent pleomorphic LCIS, ductal carcinoma-in-situ (DCIS), and invasive carcinoma were excluded. Imaging indication/modality, biopsy indication, and radiologic concordance were determined. Pathology review included scoring total foci of LN in each CNB. Upgrade rates to invasive carcinoma or DCIS at excision were calculated. RESULTS: A total of 106 cases of LN (73 ALH and 33 LCIS) on CNB were identified. Thirty patients had concurrent atypical ductal hyperplasia (ADH) and 76 had LN alone; 93 (88%) of the patients had available surgical follow-up (25 LN + ADH and 68 LN alone). The upgrade rate at excision was 16% (4 of 25) for LN + ADH and 4.4% (3 of 68) for LN alone. Patients with LN alone and discordant imaging, imaging for high-risk indications, or extensive LCIS (>4 foci) accounted for all the upgrades. Normal-risk patients who underwent biopsy to assess calcifications found by routine mammographic screening with LN alone did not result in upgrade. CONCLUSIONS: Women with a CNB diagnosis of LN for calcifications found on routine, normal-risk mammographic screening have a negligible risk of upgrade and may not require excisional biopsy. However, excisional biopsy should be offered to women undergoing imaging for other indications or with >4 foci of LN on CNB.

Association of Residual Ductal Carcinoma In Situ With Breast Cancer Recurrence in the Neoadjuvant I-SPY2 Trial.

Importance: Pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC) in breast cancer strongly correlates with overall survival and has become the standard end point in neoadjuvant trials. However, there is controversy regarding whether the definition of pCR should exclude or permit the presence of residual ductal carcinoma in situ (DCIS). Objective: To examine the association of residual DCIS in surgical specimens after neoadjuvant chemotherapy for breast cancer with survival end points to inform standards for the assessment of pathologic complete response. Design, Setting, and Participants: The study team analyzed the association of residual DCIS after NAC with 3-year event-free survival (EFS), distant recurrence-free survival (DRFS), and local-regional recurrence (LRR) in the I-SPY2 trial, an adaptive neoadjuvant platform trial for patients with breast cancer at high risk of recurrence. This is a retrospective analysis of clinical specimens and data from the ongoing I-SPY2 adaptive platform trial of novel therapeutics on a background of standard of care for early breast cancer. I-SPY2 participants are adult women diagnosed with stage II/III breast cancer at high risk of recurrence. Interventions: Participants were randomized to receive taxane and anthracycline-based neoadjuvant therapy with or without 1 of 10 investigational agents, followed by definitive surgery. Main Outcomes and Measures: The presence of DCIS and EFS, DRFS, and LRR. Results: The study team identified 933 I-SPY2 participants (aged 24 to 77 years) with complete pathology and follow-up data. Median follow-up time was 3.9 years; 337 participants (36%) had no residual invasive disease (residual cancer burden 0, or pCR). Of the 337 participants with pCR, 70 (21%) had residual DCIS, which varied significantly by tumor-receptor subtype; residual DCIS was present in 8.5% of triple negative tumors, 15.6% of hormone-receptor positive tumors, and 36.6% of ERBB2-positive tumors. Among those participants with pCR, there was no significant difference in EFS, DRFS, or LRR based on presence or absence of residual DCIS. Conclusions and Relevance: The analysis supports the definition of pCR as the absence of invasive disease after NAC regardless of the presence or absence of DCIS. Trial Registration: ClinicalTrials.gov Identifier NCT01042379.

Dynamic contrast-enhanced breast MRI features correlate with invasive breast cancer angiogenesis.

Angiogenesis is a critical component of breast cancer development, and identification of imaging-based angiogenesis assays has prognostic and treatment implications. We evaluated the association of semi-quantitative kinetic and radiomic breast cancer features on dynamic contrast-enhanced (DCE)-MRI with microvessel density (MVD), a marker for angiogenesis. Invasive breast cancer kinetic features (initial peak percent enhancement [PE], signal enhancement ratio [SER], functional tumor volume [FTV], and washout fraction [WF]), radiomics features (108 total features reflecting tumor morphology, signal intensity, and texture), and MVD (by histologic CD31 immunostaining) were measured in 27 patients (1/2016-7/2017). Lesions with high MVD levels demonstrated higher peak SER than lesions with low MVD (mean: 1.94 vs. 1.61, area under the receiver operating characteristic curve [AUC] = 0.79, p = 0.009) and higher WF (mean: 50.6% vs. 22.5%, AUC = 0.87, p = 0.001). Several radiomics texture features were also promising for predicting increased MVD (maximum AUC = 0.84, p = 0.002). Our study suggests DCE-MRI can non-invasively assess breast cancer angiogenesis, which could stratify biology and optimize treatments.

HER2 Testing: Insights From Pathologists' Perspective on Technically Challenging HER2 FISH Cases.

OBJECTIVE: College of American Pathologists and the American Society of Clinical Oncology guidelines provide straightforward criteria for HER2 interpretation in breast carcinomas; however, a subset of cases present unusual diagnostic dilemmas. MATERIALS AND METHODS: Ten challenging HER2 fluorescence in situ hybridization (FISH) cases were selected for analysis. The study included a variety of problematic cases such as those with discordant immunohistochemistry (IHC) and FISH results, cases with high intratumoral variability in HER2 copy number, a case with a highly amplified clone in 5% to 10% of the tumor sample, and a case with tumor cells containing tightly clumped HER2 signals. Six high volume HER2 FISH laboratories performed and interpreted HER2 FISH (adding HER2 IHC if necessary). Interpretation strategies were discussed. RESULTS: There was 100% concordance between laboratories in 4/10 cases. Tumors with increased intratumoral variability (tumors with high variability in HER2 copy number per cell but which otherwise do not fulfill College of American Pathologists and the American Society of Clinical Oncology criteria for heterogeneity) exhibited 100% concordance in 3/4 cases, but 1 case had only 50% agreement. Low positive HER2 cases (group 1 cases with <6 average HER2 copies/cell) had 1 laboratory disagreeing with the majority in 4/4 cases, and this was the only category with discordance between IHC and FISH methodologies. All laboratories identified the case with heterogeneity and interpreted it as positive. Five of the 6 laboratories interpreted the case with tightly clustered HER2 signals as positive. CONCLUSIONS: This study offers specific observations and interpretation strategies that laboratories can use when confronted with difficult HER 2 cases. It then highlights communication strategies a laboratory may use to discuss these unusual HER2 results with the clinical team.

Unexpected PAX8 Immunoreactivity in Metastatic High-grade Breast Cancer.

Immunohistochemistry (IHC) is often critical for distinction between metastatic carcinomas of Mullerian organ and breast origin. Paired box family protein 8 (PAX8) has been described as a transcription factor highly specific to neoplasms derived from Mullerian organs, thyroid, and kidney. PAX8 IHC with polyclonal and monoclonal antibody reagents was performed on 27 primary and 22 metastatic breast carcinomas. Eight of 27 primary breast carcinomas (30%) were positive for PAX8 with the monoclonal antibody reagent only; 0 of 22 were polyclonal anti-PAX8 immunoreactive. Substantial numbers of metastases had positive immunoreactivity for polyclonal anti-PAX8 (23%). Each of these metastases and additional cases (45% total) also had positive immunoreactivity for monoclonal anti-PAX8, including 5 of 7 brain metastases. IHC with monoclonal anti-PAX8 was positive on 6 of 7 primary breast carcinomas corresponding to PAX8-positive metastases. Together, these results indicate a significant fraction of breast carcinoma metastases and corresponding primary neoplasms have immunoreactivity for PAX8, and positivity rates depend on the antibody used. Diagnoses of metastatic breast carcinoma were achieved with the aid of clinical history and additional IHC in cases of PAX8 immunoreactivity. Contextual interpretation is imperative for PAX8 IHC, particularly when the differential diagnosis includes metastatic breast carcinoma with limited diagnostic material available.

Breast Cancer Prognostic Factors in the Digital Era: Comparison of Nottingham Grade using Whole Slide Images and Glass Slides.

BACKGROUND: To assess reproducibility and accuracy of overall Nottingham grade and component scores using digital whole slide images (WSIs) compared to glass slides. METHODS: Two hundred and eight pathologists were randomized to independently interpret 1 of 4 breast biopsy sets using either glass slides or digital WSI. Each set included 5 or 6 invasive carcinomas (22 total invasive cases). Participants interpreted the same biopsy set approximately 9 months later following a second randomization to WSI or glass slides. Nottingham grade, including component scores, was assessed on each interpretation, providing 2045 independent interpretations of grade. Overall grade and component scores were compared between pathologists (interobserver agreement) and for interpretations by the same pathologist (intraobserver agreement). Grade assessments were compared when the format (WSI vs. glass slides) changed or was the same for the two interpretations. RESULTS: Nottingham grade intraobserver agreement was highest using glass slides for both interpretations (73%, 95% confidence interval [CI]: 68%, 78%) and slightly lower but not statistically different using digital WSI for both interpretations (68%, 95% CI: 61%, 75%; P= 0.22). The agreement was lowest when the format changed between interpretations (63%, 95% CI: 59%, 68%). Interobserver agreement was significantly higher (P < 0.001) using glass slides versus digital WSI (68%, 95% CI: 66%, 70% versus 60%, 95% CI: 57%, 62%, respectively). Nuclear pleomorphism scores had the lowest inter- and intra-observer agreement. Mitotic scores were higher on glass slides in inter- and intra-observer comparisons. CONCLUSIONS: Pathologists' intraobserver agreement (reproducibility) is similar for Nottingham grade using glass slides or WSI. However, slightly lower agreement between pathologists suggests that verification of grade using digital WSI may be more challenging.

Epithelioid angiosarcoma arising in a uterine leiomyoma with associated elevated CA-125: A case report.

We describe the case of a 67 year old female with longstanding uterine leiomyomas who presented with fatigue, weight loss, elevated CA-125 and an enlarging mass arising from the posterior uterine fundus. Histologic sections of the mass contained a leiomyoma with interspersed foci of malignant epithelioid cells forming anastomosing vascular channels. The neoplastic cells were diffusely positive for CD31 and FLI1, supporting the morphologic impression of epithelioid angiosarcoma. Few cases of epithelioid angiosarcoma arising within a leiomyoma have been described. In this report we discuss this association and describe its relation with elevated CA-125.

Comparison of Proliferation Markers Ki67 and Phosphohistone-H3 (pHH3) in Breast Ductal Carcinoma In Situ.

Proliferative index is a prognostic feature of invasive ductal carcinoma of the breast, and has more recently emerged as a predictor of ductal carcinoma in situ (DCIS) local recurrence and progression when used in combination with other predictive markers. Ki67 is the most commonly used immunohistochemical marker of proliferative index. However, high interobserver and interlaboratory variability has been reported, in part due to differences in staining methodologies, positivity thresholds, and approaches to quantification. Phosphohistone-H3 (pHH3) is a marker of mitotic activity that has emerged as a more reliable indicator of proliferation in other neoplasms. Quantification of proliferative index was compared in 48 cases of DCIS using Ki67 and pHH3 immunohistochemistry. A strong linear relationship between Ki67 and pHH3 quantification was observed (P<0.0001, R=0.75). Interobserver concordance was modestly higher for pHH3 than Ki67 proliferative indices. However, positive pHH3 staining was more dichotomous (either negative or uniformly positive) and specific for mitotic activity, and interpretation of pHH3 proliferative indices was significantly faster than that of Ki67. The strong correlation between pHH3 and Ki67 supports the use of this marker as a measure of proliferative activity in DCIS.

NDER: A Novel Web Application for Teaching Histology to Medical Students.

Medical students require a strong foundation in normal histology. However, current trends in medical school curricula have diminished time devoted to histology. Thus, there is a need for more efficient methods of teaching histology. We have developed a novel software program (Novel Diagnostic Educational Resource; https://pcs-webtest0.pathology.washington.edu/academics/pattern/) that uses annotated whole slide images to teach normal histology. Whole slide images of a wide variety of tissues were annotated by a trainee and validated by an experienced pathologist. Still images were extracted and transferred to the Novel Diagnostic Educational Resource web application. In Novel Diagnostic Educational Resource, an image was displayed briefly and the user was forced to identify the tissue type. The display time changed inversely based on cumulative accuracy to challenge the user and maintain engagement. A total of 129 second-year medical students completed the 30-minute Novel Diagnostic Educational Resource module. Surveys showed an increase in confidence from premodule (0% extremely confident, 4% very, 47% somewhat, and 49% not) to postmodule (9% extremely confident, 57% very, 32% somewhat, and 2% not), P < .0001. Accuracy increased from 72.6% pretest to 95.7% posttest, P < .002. The effect size (Cohen d = 2.30) was very large, where 0.2 is a small effect, 0.5 moderate, and 0.8 large. Ninety-six percent of students would recommend Novel Diagnostic Educational Resource to other medical students, and 98% would use Novel Diagnostic Educational Resource to further enhance their histology knowledge. Novel Diagnostic Educational Resource drastically improved medical student accuracy in classifying normal histology and improved confidence. Additional study is needed to determine knowledge retention, but Novel Diagnostic Educational Resource has great potential for efficient teaching of histology given the curriculum time constraints in medical education.