Modern Pathology最新文献

Tall cell carcinoma with reversed polarity (TCCRP) is a rare neoplasm of the breast composed of columnar tumor cells arranged in solid and solid papillary nests with evidence of apical nuclear polarity. No frank invasion is evident despite the lack of a myoepithelial cell layer throughout the tumor. TCCRP has a triple negative or hormone receptor-low immunophenotype. Recurrent IDH2 R172 hotspot mutation coexisting with genetic alterations in the PI3K pathway characterize this tumor. Here, we report on two postmenopausal patients with TCCRPs with frank stromal invasion. IDH2 R172 mutations were detected in both tumors by immunohistochemistry. Targeted sequencing of case 2 demonstrated the presence of IDH2 R172T and RTEL1 E839K mutations. Both patients underwent breast conservation surgery, radiation therapy and adjuvant endocrine therapy with anastrozole and show no evidence of disease at 65 and 25 months, respectively. This study suggests that tall cell carcinoma with reversed polarity may give rise to frank invasive carcinoma, the prognostic significance of which is yet unknown.

The potential of artificial intelligence (AI) in digital pathology is limited by technical inconsistencies in the production of whole slide images (WSIs). This causes degraded AI performance and poses a challenge for widespread clinical application, as fine-tuning algorithms for each site is impractical. Changes in the imaging workflow can also compromise diagnostic accuracy and patient safety. Physical color calibration of scanners, relying on a biomaterial-based calibrant slide and a spectrophotometric reference measurement, has been proposed for standardizing WSI appearance, but its impact on AI performance has not been investigated. We evaluated whether physical color calibration can enable robust AI performance. We trained fully supervised and foundation model based AI systems for detecting and Gleason grading prostate cancer using WSIs of prostate biopsies from the STHLM3 clinical trial (n=3,651) and evaluated their performance in three external cohorts (n=1,161) with and without calibration. With physical color calibration, the fully supervised system's concordance with pathologists' grading (Cohen's linearly weighted kappa) improved from 0.439 to 0.619 in the Stavanger University Hospital cohort (n=860), from 0.354 to 0.738 in the Karolinska University Hospital cohort (n=229), and from 0.423 to 0.452 in the Aarhus University Hospital cohort (n=72). The foundation model's concordance improved from 0.739 to 0.760 (Karolinska), from 0.424 to 0.459 (Aarhus) and from 0.547 to 0.670 (Stavanger). The study demonstrates that physical color calibration provides a potential solution to the variation introduced by different scanners, making AI-based cancer diagnostics more reliable and applicable in diverse clinical settings.

Claudin 18.2 (CLDN18.2) immunohistochemical expression can be used to select patients with gastric/gastroesophageal junction adenocarcinomas for zolbetuximab (IMAB362) therapy, a monoclonal antibody targeting CLDN18.2. The aim of this study was to correlate immunohistochemical expression of CLDN18.2 with clinicopathologic and molecular features in a large series of digestive tract cancers. Immunohistochemistry (IHC) for CLDN18.2 was performed on tissue microarrays from 1404 adenocarcinomas including 155 gastric/gastroesophageal, 74 pancreatic ductal, 1175 colorectal (576 in initial test cohort; 599 in subsequent validation cohort), and correlated with HER2 and mismatch repair (MMR) status. Cases were scored as CLDN18.2 positive or negative, with positivity defined as moderate to strong membranous staining in >75% of tumor cells. CLDN18.2 expression was correlated with clinicopathologic and molecular features for all colorectal adenocarcinomas. CLDN18.2 was positive in 39% (61/155) of gastric/gastroesophageal adenocarcinomas, 38% (28/74) of pancreatic ductal adenocarcinomas, and 3.4% (40/1175) of colorectal adenocarcinomas (p<0.001). For gastric/gastroesophageal and pancreatic ductal adenocarcinoma, there was no correlation between CLDN18.2 expression and either HER2 or MMR status. In contrast, CLDN18.2-positive colorectal adenocarcinomas had distinct clinicopathologic and molecular features. CLDN18.2-positive colorectal adenocarcinomas were more frequently proximally located and were more often MMR deficient and BRAF V600E positive (all with p<0.05). Quantitative pathologic analysis using the digital pathology biomarker QuantCRC demonstrated marked differences in histologic features between CLDN18.2-positive and negative colorectal adenocarcinomas, with CLDN18.2-positive tumors having increased tumor:stroma ratio and %mucin but decreased %immature stroma in both the test and validation cohorts (all with p<0.05). In conclusion, CLDN18.2-positive colorectal adenocarcinomas are frequently MMR deficient, BRAF V600E mutated, and demonstrate distinct histologic features. Future studies addressing the efficacy of zolbetuximab therapy in this subset of colorectal cancers are needed.

HER2-positive breast cancer (BC), which constitutes 13-15% of cases, shows variable response to anti-HER2 therapies. HER2-positivity, defined as protein overexpression (immunohistochemistry (IHC) score 3+) or equivocal expression (IHC 2+) with evidence of HER2 gene amplification, determines the eligibility to anti-HER2 therapy. MammaTyper® assay (Cerca Biotech GmbH) is a RT-qPCR BC subtyping platform based on the mRNA expression of ERBB2, ESR1, PGR, and MKI67. This study aims to evaluate the accuracy of the MammaTyper® assay in predicting the response of HER2-positive patients to therapy. A well-characterized HER2-positive BC cohort of 287 cases diagnosed at Nottingham University hospitals between 2006 and 2018 was included. The cohort was divided into 2 groups: a trastuzumab-treated group (n=159) and a chemotherapy-only treated group (n=128). Tumor clinicopathologic characteristics were matched between the two groups. Cases with discordant HER2 status were validated through staining of surgical excision specimens. ERBB2 mRNA identified 251/287 (87.5%) cases as HER2-positive, 10.8% (31/287) as HER2 low and 1.7% (5/287) as HER2-negative. According to MammaTyper® assay, ERBB2-positive patients treated with anti-HER2 therapy had significantly prolonged 5-year disease (DFS) and distant metastasis (DMFS) free survival (HR=0.56, p=0.003 and HR=0.62, p=0.023, respectively). MammaTyper®-defined HER2-Enriched subtype showed better response to anti-HER2 therapy compared to IHC-defined subtypes, with significant differences in both 5-year DFS and BCSS (p=0.01 and <0.001, respectively). ERBB2-negative patients did not show survival difference between the group of patients who were treated with trastuzumab and those who were treated with chemotherapy only (p>0.05). Validation analysis revealed that 11/36 ERBB2-negative cases were IHC 2+/ISH positive with very low level of gene amplification and 25 cases were false classified as HER2 positive using current protocols. Combining MammaTyper® assay with IHC to assess HER2 status improves the identification of HER2-positive BC patients who would benefit from anti-HER2 therapy.

Fibrolamellar carcinoma (FLC) is a unique primary carcinoma of liver that is characterized by distinct morphologic findings and a recurrent DNAJB1::PRKACA gene fusion. It typically presents in young individuals without underlying liver dysfunction. FLC is a difficult diagnosis when based only on morphology and misdiagnosis is not uncommon. Frequent differential diagnoses include conventional hepatocellular carcinoma and intrahepatic cholangiocarcinoma, both of which can show similar morphologic and immunohistochemical features. If based only on molecular analysis other differential diagnoses have recently emerged, as the DNAJB1::PRKACA fusion has now been reported in cases of intraductal oncocytic papillary neoplasm and intraductal papillary mucinous neoplasm. In this article we review our diagnostic approach to FLC, which relies on both morphologic and immunohistochemical features, as well as molecular analysis.

Classification of cases of diffuse large B-cell lymphoma (DLBCL)/high-grade B-cell lymphoma (HGBL) with MYC and BCL6 rearrangements, also known as BCL6 double hit lymphoma (DHL), is controversial. We assessed 60 cases of BCL6-DHL and compared this cohort to 224 cases of DHL with MYC and BCL2 rearrangements (BCL2-DHL) and 217 cases of DLBCL not otherwise specified. Compared with the DLBCL cohort, BCL6-DHL patients had more aggressive clinical features such as frequent extranodal involvement, high-stage disease, high IPI score and elevated serum lactate dehydrogenase level (p <0.01 for all). Compared with the BCL2-DHL cohort, BCL6-DHL patients had similarly aggressive clinical features but a lower frequency of germinal center B-cell (GCB) immunophenotype and MYC and BCL2 double expression. Patients with BCL6-DHL showed an overall survival (OS) intermediate between patients with DLBCL and BCL2-DHL. Following induction with R-CHOP chemotherapy, BCL6-DHL patients demonstrated a poor OS similar to BCL2-DHL patients and worse than that of DLBCL patients (p = 0.024). However, among patients who received R-EPOCH, there was no significant difference in OS among the three groups (p = 0.146). Gene expression profiling showed that 60% of BCL6-DHL cases had a double hit (DH)-like signature compared with 10% of DLBCL-GCB and 93% of BCL2-DHL. The DH-like signature in BCL6-DHL cases was associated with a GCB immunophenotype. Based on these data, we suggest that BCL6-DHL cases are clinically more aggressive than DLBCL and patients may benefit from a more aggressive therapy than R-CHOP. The data also suggest that BCL6-DHL as currently defined, is heterogeneous and that neoplasms with a GCB immunophenotype are more likely to have DH-like signature and behave more aggressively. Lastly, we suggest that BCL6-DHL cases deserve to be recognized separately in a lymphoma classification to facilitate further understanding of these neoplasms and for optimal patient management.

Deep penetrating nevi (DPNs) are characterized by activating mutations in the MAP kinase and Wnt/beta-catenin pathways that result in large melanocytes with increased nuclear atypia, cytoplasmic pigmentation, and often mitotic activity. Together with a lack of maturation, this constellation of findings creates challenges for pathologists to distinguish deep penetrating nevus (DPN) from DPN-like melanoma. To assess the utility of next generation sequencing (NGS) in resolving this diagnostic dilemma, we performed NGS studies on 35 lesions including 24 DPNs and 11 DPN-like melanomas to characterize the specific genomic differences between the two groups and elucidate the genetic events involved in malignant transformation of DPNs. Compared to DPNs, DPN-like melanomas were clinically larger in size (1.1 vs 0.6 cm, p=0.02) and on histopathologic examination more frequently showed high grade nuclear atypia (11/11 vs 9/24; p=0.00052), increased mitotic activity (mean 3.9 vs 1.3 per mm²; p=0.0004), sheet-like growth pattern (5/11 vs 2/24; p=0.01), and involvement of the subcutis (4/5 vs 3/13; p=0.026). From a genomic standpoint, DPN-like melanomas had a higher tumor mutation burden (mean 37.1 vs 7.8 mutations/megabase; p=0.002) than DPNs and more frequently harbored NRAS mutation (3/11 vs 1/24; p=0.046) whereas MAP2K1 in frame deletions were only identified in DPNs (0/11 vs 5/24). There was no statistically significant difference in the frequency or type of CTNNB1 or APC mutations between the two groups. Within progression genes, DPN-like melanomas were more frequently found to have pathogenic variants in TERT promoter (7/11 vs 0/24; p<0.00001), CDKN2A (4/11 vs 0/24; p=0.0008), and protein subunits of the SWI/SNF complex (7/11 vs 3/24; p=0.02) compared to DPNs. Our findings provide a framework for employing NGS in the evaluation of deep penetrating melanocytic tumors.

Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease. About 10% of affected individuals have an inherited component. Deleterious germline variants increase the lifetime risk for PDAC and are often associated with an elevated risk for extra-pancreatic malignancies. In this study, we aim to determine the prevalence and impact of germline pathogenic variants (gPVs) in patients with PDAC and extra-pancreatic malignancies. Using tissue samples and longitudinal data from a nationwide pathology database, we identified patients with PDAC and a set of seven extra-pancreatic malignancies to investigate the presence of gPVs in 25 cancer susceptibility genes with targeted next-generation sequencing. Of 473 PDAC patients with at least one extra-pancreatic malignancy, 75 (16%) had gPVs. These were predominantly in ATM (n=22), CDKN2A (n=14), BRCA2 (n=10), or CHEK2 (n=10) genes. The combination of PDAC and ovarian carcinoma carried the highest prevalence of gPVs (4 of 10; 40%), followed by PDAC and melanoma (15 of 53; 28%), and PDAC and gastric cancer (2 of 9; 22%). PDAC patients with certain extra-pancreatic malignancies carry a higher burden of gPVs than unselected PDAC cohorts. This is a group that very likely benefits from genetic testing since germline status can have important diagnostic and therapeutic implications for affected individuals and their family members.

Histologic features, including architectural patterns, cytologic features, and 2021 World Health Organization nuclear grade have been shown to have prognostic significance in epithelioid diffuse pleural mesothelioma (DPM). Biphasic and sarcomatoid DPM, regardless of morphology, have worse outcomes. These prognostic findings are well-established but correlation of architectural patterns, cytologic features, and nuclear grade with genetic alterations has not been well studied. To investigate relationships between histologic findings and genomic alterations, 128 treatment-naïve DPM specimens (70% epithelioid, 23% biphasic and 6.3% sarcomatoid) with next generation sequencing data were retrospectively reviewed. Alterations in BAP1 were the most common genomic alteration (n=62, 48%), followed by CDKN2A (n=49, 38%) and NF2 (n=38, 30%). NF2 alterations were significantly more frequent in biphasic DPM (53% in biphasic versus 25% in sarcomatoid and 22% in epithelioid; p=0.005). In epithelioid DPM, TP53 alterations were associated with presence of prognostically unfavorable histology, including micropapillary or solid architecture, pleomorphic features and high nuclear grade. Tumors with low tumor infiltrating lymphocytes had a higher rate of BAP1 alterations compared to tumors with higher levels of tumor infiltrating lymphocytes (67% versus 30%; p=0.002). The findings of this study enhance our understanding of the relationships among prognostically significant histologic and molecular features of DPM and provide preliminary data to support increased integration of these findings in clinical diagnosis of pleural mesothelioma.

Different types of digital modalities are currently available for frozen section (FS) evaluation in surgical pathology practice. However, there are limited studies that demonstrate the potential of whole slide imaging (WSI) as a robust digital pathology option for FS FS diagnosis. In the current study, we compared the diagnostic accuracy achieved with WSI to that achieved with Light Microscopy (LM) for evaluating FSs of axillary sentinel lymph nodes (SLNs) and clipped lymph nodes (LNs) from breast cancer patients using two modalities. Initially, a retrospective analysis evaluated hematoxylin and eosin (H&E)-stained FSs of 109 SLNs using WSI followed by LM after a wash-out period ranging from 2 to 6 weeks. Subsequently, a prospective analysis assessed FSs of 132 SLNs using LM by first pathologist, then H&E-stained FSs were scanned and interpreted remotely in real-time by a different pathologist. In the retrospective analysis, the diagnostic accuracy utilizing WSI, ranged from 96% to 99%, exhibited similarity to those achieved with LM, ranging from 94% to 99%. Similarly, the prospective analysis also demonstrated comparable diagnostic accuracy between WSI (96.2%) and LM (97%). Pathologists in the retrospective study required an additional 0.8-5.4 minutes to render diagnoses using WSI compared to LM (p<0.0001). In the prospective study conducted two years later, pathologists only took slightly longer to provide WSI FS diagnoses (3.95 min) compared to LM (3.51 min) (P>0.05). In conclusion, our study indicated that WSI-based evaluation showed comparable diagnostic accuracy to LM for assessing LN FSs. Furthermore, the prospective study demonstrated the feasibility of real-time acquisition of high-quality WSIs for remote FS diagnosis of SLNs. These findings substantiate the promising potential of using WSIs of SLNs and clipped LNs in real time FS evaluation of breast cancer patients as a standard of care in surgical pathology practice.