High risk features in colorectal adenomatous polyps: A multi-institutional study.

High risk features in colorectal adenomatous polyps include size >1 cm and advanced histology: high-grade dysplasia and villous architecture. We investigated whether the diagnostic rates of advanced histology in colorectal adenomatous polyps were similar among institutions across the United States, and if not, could differences be explained by patient age, polyp size, and/or CRC rate. Nine academic institutions contributed data from three pathologists who had signed out at least 100 colorectal adenomatous polyps each from 2018 to 2019 taken from patients undergoing screening colonoscopy. For each case, we recorded patient age and sex, polyp size and location, concurrent CRC, and presence or absence of HGD and villous features. A total of 2700 polyps from 1886 patients (mean age: 61 years) were collected. One hundred twenty-four (5 %) of the 2700 polyps had advanced histology, including 35 (1 %) with HGD and 101 (4 %) with villous features. The diagnostic rate of advanced histology varied by institution from 1.7 % to 9.3 % (median: 4.3 %, standard deviation [SD]: 2.5 %). The rate of HGD ranged from 0 % to 3.3 % (median: 1 %, SD: 1.2 %), while the rate of villous architecture varied from 1 % to 8 % (median: 3.7 %, SD: 2.5 %). In a multivariate analysis, the factor most strongly associated with advanced histology was polyp size >1 cm with an odds ratio (OR) of 31.82 (95 % confidence interval [CI]: 20.52-50.25, p < 0.05). Inter-institutional differences in the rate of polyps >1 cm likely explain some of the diagnostic variance, but pathologic subjectivity may be another contributing factor.

Nonconventional Dysplasia is Frequently Associated With Goblet Cell Deficient and Serrated Variants of Colonic Adenocarcinoma in Inflammatory Bowel Disease.

Various subtypes of nonconventional dysplasia have been recently described in inflammatory bowel disease (IBD). We hypothesized that goblet cell deficient dysplasia and serrated dysplasia may be the primary precursor lesions for goblet cell deficient (GCDAC) and serrated (SAC) variants of colonic adenocarcinoma, respectively. Clinicopathologic features of 23 GCDAC and 10 SAC colectomy cases were analyzed. All dysplastic lesions found adjacent to the colorectal cancers (n = 22 for GCDACs and n = 10 for SACs) were subtyped as conventional, nonconventional, or mixed-type dysplasia. As controls, 12 IBD colectomy cases with well to moderately differentiated adenocarcinoma that lacked any mucinous, signet ring cell, low-grade tubuloglandular, or serrated features while retaining goblet cells throughout the tumor (at least 50% of the tumor) were evaluated. The cohort consisted of 19 (58%) men and 14 (42%) women, with a mean age of 53 years and a long history of IBD (mean duration: 18 y). Twenty-seven (82%) patients had ulcerative colitis. GCDACs (57%) were more often flat or invisible than SACs (10%) and controls (25%; P = 0.023). The GCDAC and SAC groups were more likely to show lymphovascular invasion (GCDAC group: 52%, SAC group: 50%, control group: 0%, P = 0.001) and lymph node metastasis (GCDAC group: 39%, SAC group: 50%, control group: 0%, P = 0.009) than the control group. Notably, GCDACs and SACs were more frequently associated with nonconventional dysplasia than controls (GCDAC group: 77%, SAC group: 40%, control group: 0%, P < 0.001). Goblet cell deficient dysplasia (73%) was the most prevalent dysplastic subtype associated with GCDACs ( P = 0.049), whereas dysplasias featuring a serrated component (60%) were most often associated with SACs ( P = 0.001). The GCDAC group (75%) had a higher rate of macroscopically flat or invisible synchronous dysplasia compared with the SAC (20%) and control (33%) groups ( P = 0.045). Synchronous dysplasia demonstrated nonconventional dysplastic features more frequently in the GCDAC (69%) and SAC (40%) groups compared with the control group (0%; P = 0.016). In conclusion, goblet cell deficient dysplasia and dysplasias featuring a serrated component could potentially serve as high-risk markers for GCDACs and SACs, respectively.

Clinical Data Do Not Reliably Predict Duodenal Histology at Follow-up in Celiac Disease: A 13 Center Correlative Study.

Validated nonbiopsy methods to assure duodenal mucosal healing in celiac disease are lacking, yet ongoing mucosal injury is associated with anemia, osteoporosis, and lymphoma. Most providers utilize clinical data as surrogates of mucosal status to avoid additional esophagogastroduodenoscopy. The reliability of such surrogates to predict mucosal recovery has been incompletely evaluated. The aim of this study was to rigorously assess patterns of histologic mucosal recovery at follow-up in celiac disease and to correlate findings with clinical data. Gastrointestinal pathologists from 13 centers evaluated initial and follow-up duodenal biopsies from 181 celiac disease patients. Marsh scores and intraepithelial lymphocytes (IELs)/100 enterocytes were assessed blindly. Histology at follow-up was correlated with symptoms, immunoglobulin A anti-tissue transglutaminase titers and gluten-free diet adherence. Fifty-six/181 (31%) patients had persistent villous blunting and 46/181 (25%) patients had just persistently elevated IELs at follow-up, with only 79/181 (44%) patients having complete histologic remission. IEL normalization (82/181; 45%) lagged villous recovery (125/181;69%). In a minority of patients, villous blunting was limited to proximal duodenal biopsies. No correlation was found between Marsh scores and symptoms, normalization of immunoglobulin A anti-tissue transglutaminase serology, or diet adherence. Children showed greater recovery of Marsh score ( P <0.001) and IELs ( P <0.01) than adults. Persistent mucosal injury is common in celiac disease, with discordant villous/IEL normalization. Pathologist awareness of expected findings in celiac disease follow-up biopsies, including their frequent lack of correlation with clinical data, is important for patient management, and has implications for eligibility criteria for therapeutics currently in development.

Erythrophagocytosis is not a reproducible finding in liver biopsies, and is not associated with clinical diagnosis of hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a rare disease with high mortality. Liver involvement is common (based on elevated liver function tests) with most patients demonstrating acute hepatitis. Liver biopsies are frequently obtained in the setting of suspected HLH for the purpose of identification of erythrophagocytosis, and if present, this finding is thought to suggest or support the diagnosis of HLH. However, there are problems with this approach; in particular, we do not know whether this finding is reproducible or whether it is specific to HLH. Therefore, we conducted a multi-institutional study in which experienced liver pathologists reviewed images taken from liver biopsies from patients with normal liver, acute hepatitis, possible HLH, and clinical HLH to determine if there was agreement about the presence or absence of erythrophagocytosis, and to ascertain whether the finding corresponds to a clinical diagnosis of HLH. Twelve liver pathologists reviewed 141 images in isolation (i.e., no clinical information or diagnosis provided). These came from 32 patients (five normal, 17 acute hepatitis, six HLH, four possible HLH). The pathologists classified each image as negative, equivocal, or positive for erythrophagocytosis. Kappa was .08 (no agreement) for case-level and 0.1 for image-level (1.4% agreement, based on two images which were universally considered negative). There was no difference in the proportion of pathologists who diagnosed erythrophagocytosis among those with different diagnoses at case or image-level (p = 0.82 and p = 0.82, respectively). Thus, erythrophagocytosis is an entirely unreliable histologic parameter in liver, as it is irreproducible and not demonstrably associated with a clinical disease (namely, HLH). Unless and until more reliable guidelines can be established, pathologists should refrain from commenting on the presence or absence of erythrophagocytosis in liver biopsy.

Image-localized biopsy mapping of brain tumor heterogeneity: A single-center study protocol.

Brain cancers pose a novel set of difficulties due to the limited accessibility of human brain tumor tissue. For this reason, clinical decision-making relies heavily on MR imaging interpretation, yet the mapping between MRI features and underlying biology remains ambiguous. Standard (clinical) tissue sampling fails to capture the full heterogeneity of the disease. Biopsies are required to obtain a pathological diagnosis and are predominantly taken from the tumor core, which often has different traits to the surrounding invasive tumor that typically leads to recurrent disease. One approach to solving this issue is to characterize the spatial heterogeneity of molecular, genetic, and cellular features of glioma through the intraoperative collection of multiple image-localized biopsy samples paired with multi-parametric MRIs. We have adopted this approach and are currently actively enrolling patients for our 'Image-Based Mapping of Brain Tumors' study. Patients are eligible for this research study (IRB #16-002424) if they are 18 years or older and undergoing surgical intervention for a brain lesion. Once identified, candidate patients receive dynamic susceptibility contrast (DSC) perfusion MRI and diffusion tensor imaging (DTI), in addition to standard sequences (T1, T1Gd, T2, T2-FLAIR) at their presurgical scan. During surgery, sample anatomical locations are tracked using neuronavigation. The collected specimens from this research study are used to capture the intra-tumoral heterogeneity across brain tumors including quantification of genetic aberrations through whole-exome and RNA sequencing as well as other tissue analysis techniques. To date, these data (made available through a public portal) have been used to generate, test, and validate predictive regional maps of the spatial distribution of tumor cell density and/or treatment-related key genetic marker status to identify biopsy and/or treatment targets based on insight from the entire tumor makeup. This type of methodology, when delivered within clinically feasible time frames, has the potential to further inform medical decision-making by improving surgical intervention, radiation, and targeted drug therapy for patients with glioma.

Non-conventional dysplasia is frequently associated with low-grade tubuloglandular and mucinous adenocarcinomas in inflammatory bowel disease.

There is limited information regarding the clinicopathological features of low-grade tubuloglandular (LGTGA) and mucinous (MAC) adenocarcinomas occurring in inflammatory bowel disease (IBD), especially with regard to their precursor lesions. METHODS AND RESULTS: Forty-six IBD colectomy specimens with LGTGA (n = 17) or MAC (n = 29) with adjacent precursor lesions were analysed. As controls, 12 IBD colectomy specimens with well- to moderately differentiated adenocarcinoma that lacked any mucinous, signet ring cell, low-grade tubuloglandular or serrated features were also analysed. Compared with MACs and controls, LGTGAs more often had a flat/invisible macroscopic appearance (LGTGAs = 88%, MACs = 34%, controls = 25%, P < 0.001). MACs were more likely to have high-grade differentiation (MACs = 31%, LGTGAs = 0%, controls = 0%, P = 0.002) and a higher pathological stage (pT3 and pT4 MACs = 76%, LGTGAs = 35%, controls = 33%, P = 0.007) than LGTGAs and controls. LGTGAs (70%) and MACs (53%) were more frequently associated with non-conventional dysplasia than controls (0%) (P < 0.001). Crypt cell (40%) and hypermucinous (34%) dysplasias were the most common non-conventional subtypes associated with LGTGAs and MACs, respectively. Synchronous dysplasia often demonstrated non-conventional features in the LGTGA (33%) and MAC (47%) groups (versus 0% for the control group, P = 0.074). Synchronous cancer frequently showed similar histological features as the main tumour (LGTGA group = 60%, MAC group = 38%, control group = 100%). CONCLUSIONS: Crypt cell and hypermucinous dysplasias are the most common precursor lesions associated with LGTGAs and MACs, respectively, and may serve as a marker of increased risk for these cancer subtypes.

Pembrolizumab in Combination with Neoadjuvant Chemoradiotherapy for Patients with Resectable Adenocarcinoma of the Gastroesophageal Junction.

PURPOSE: This phase Ib/2 trial investigated pembrolizumab-containing trimodality therapy in patients with gastroesophageal junction (GEJ) adenocarcinoma. PATIENTS AND METHODS: Patients with GEJ adenocarcinoma (cT1-3NanyM0) received neoadjuvant pembrolizumab-containing chemoradiation (CROSS regimen) followed by surgical resection and adjuvant pembrolizumab. The primary endpoints were tolerability in the first 16 patients and pathologic complete response [pCR (ypT0N0)]. Secondary endpoints included progression-free survival (PFS) and overall survival (OS). An independent propensity-score-matched cohort (treated with CROSS without immunotherapy) was used for comparison. Exploratory analyses included immune biomarkers in the tumor microenvironment (TME) and plasma. RESULTS: We enrolled 31 eligible patients, of whom 29 received all expected doses of neoadjuvant pembrolizumab and 28 underwent R0 resection. Safety endpoints were met. The primary efficacy endpoint was not met [7/31 (22.6%) achieved pCR]. Patients with high [i.e., combined positive score (CPS) ≥ 10] baseline expression of programmed death (PD)-L1 in the TME had a significantly higher pCR rate than those with low expression [50.0% (4/8) vs. 13.6% (3/22); P = 0.046]. Patients with high PD-L1 expression also experienced longer PFS and OS than propensity-score-matched patients. Among trial patients with PD-L1 CPS < 10, unprespecified analysis explored whether extracellular vesicles (EV) could identify further responders: an elevated plasma level of PD-L1-expressing EVs was significantly associated with higher pCR. CONCLUSIONS: Adding pembrolizumab to trimodality therapy showed acceptable tolerability but did not meet the pre-specified pCR endpoint. Exploratory analyses suggested that high PD-L1 expression in the TME and/or on EVs may identify patients most likely to achieve tumor response.

Invasive carcinoma versus pseudoinvasion: interobserver variability in the assessment of left-sided colorectal polypectomies.

OBJECTIVES: Misplaced epithelium in adenomas can occasionally be difficult to distinguish from invasive adenocarcinoma. We evaluated interobserver variability in the assessment of left-sided colon polypectomies for pseudoinvasion versus invasive adenocarcinoma and further investigated relevant histological findings. METHODS: 28 consecutive left-sided colon polyps with the keywords "pseudoinvasion", "epithelial misplacement", "herniation", "prolapse" or "invasive adenocarcinoma" were collected from 28 patients and reviewed by eight gastrointestinal pathologists. Participants assessed stromal hemosiderin, lamina propria/eosinophils surrounding glands, desmoplasia, high grade dysplasia/intramucosal adenocarcinoma and margin status and rendered a diagnosis of pseudoinvasion, invasive adenocarcinoma, or both. RESULTS: Agreement among pathologists was substantial for desmoplasia (κ=0.70), high grade dysplasia/intramucosal adenocarcinoma (κ=0.66), invasive adenocarcinoma (κ=0.63) and adenocarcinoma at the margin (κ=0.65). There was moderate agreement for hemosiderin in stroma (κ=0.53) and prolapse/pseudoinvasion (κ=0.50). Agreement was low for lamina propria/eosinophils around glands (κ=0.12). For invasive adenocarcinoma, seven or more pathologists agreed in 24 of 28 cases (86%), and there was perfect agreement in 19/28 cases (68%). For pseudoinvasion, seven or more pathologists agreed in 19 of 28 cases (68%), and there was perfect agreement in 16/28 cases (57%). CONCLUSION: Moderate to substantial, though imperfect, agreement was achieved in the distinction of pseudoinvasion from invasive carcinoma.

Synergistic combination of cytotoxic chemotherapy and cyclin-dependent kinase 4/6 inhibitors in biliary tract cancers.

BACKGROUND AND AIMS: Biliary tract cancers (BTCs) are uncommon, but highly lethal, gastrointestinal malignancies. Gemcitabine/cisplatin is a standard-of-care systemic therapy, but has a modest impact on survival and harbors toxicities, including myelosuppression, nephropathy, neuropathy, and ototoxicity. Whereas BTCs are characterized by aberrations activating the cyclinD1/cyclin-dependent kinase (CDK)4/6/CDK inhibitor 2a/retinoblastoma pathway, clinical use of CDK4/6 inhibitors as monotherapy is limited by lack of validated biomarkers, diffident preclinical efficacy, and development of acquired drug resistance. Emerging studies have explored therapeutic strategies to enhance the antitumor efficacy of CDK4/6 inhibitors by the combination with chemotherapy regimens, but their mechanism of action remains elusive. APPROACH AND RESULTS: Here, we report in vitro and in vivo synergy in BTC models, showing enhanced efficacy, reduced toxicity, and better survival with a combination comprising gemcitabine/cisplatin and CDK4/6 inhibitors. Furthermore, we demonstrated that abemaciclib monotherapy had only modest efficacy attributable to autophagy-induced resistance. Notably, triplet therapy was able to potentiate efficacy through elimination of the autophagic flux. Correspondingly, abemaciclib potentiated ribonucleotide reductase catalytic subunit M1 reduction, resulting in sensitization to gemcitabine. CONCLUSIONS: As such, these data provide robust preclinical mechanistic evidence of synergy between gemcitabine/cisplatin and CDK4/6 inhibitors and delineate a path forward for translation of these findings to preliminary clinical studies in advanced BTC patients.

Silk Embolic Material for Catheter-Directed Endovascular Drug Delivery.

Embolization is a catheter-based minimally invasive procedure that deliberately occludes diseased blood vessels for treatment purposes. A novel silk-based embolic material (SEM) that is developed and optimized to provide tandem integration of both embolization and the delivery of therapeutics is reported. Natural silk is processed into fibroin proteins of varying lengths and is combined with charged nanoclay particles to allow visibility and injectability using clinical catheters as small as 600 µm in diameter at lengths >100 cm. SEMs loaded with fluorochrome labeled bovine albumin and Nivolumab, which is among the most used immunotherapy drugs worldwide, demonstrate a sustained release profile in vitro over 28 days. In a porcine renal survival model, SEMs with labeled albumin and Nivolumab successfully embolize porcine arteries without recanalization and lead to the delivery of both albumin and Nivolumab into the interstitial space of the renal cortex. Mechanistically, it is shown that tissue delivery is most optimal when the internal elastic membrane of the embolized artery is disrupted. SEM is a potential next-generation multifunctional embolic agent that can achieve embolization and deliver a wide range of therapeutics to treat vascular diseases including tumors.

Hypermucinous, Goblet Cell-Deficient and Crypt Cell Dysplasias in Inflammatory Bowel Disease are Often Associated with Flat/Invisible Endoscopic Appearance and Advanced Neoplasia on Follow-Up.

BACKGROUND AND AIMS: Several different types of non-conventional dysplasia have been recently described in inflammatory bowel disease [IBD]. Hypermucinous, goblet cell-deficient and crypt cell dysplasias have received most attention, but there is limited information regarding their clinicopathological features and clinical outcomes. METHODS: A total of 126 cases of hypermucinous [n = 55], goblet cell-deficient [n = 26] and crypt cell [n = 45] dysplasias from 97 IBD patients were collected from seven different institutions and analysed. RESULTS: The cohort included 62 [64%] men and 35 [36%] women with a mean age of 49 years [range: 20-78]. The majority of affected patients had longstanding IBD [mean duration: 18 years]. Nineteen [20%] patients had a concurrent history of primary sclerosing cholangitis. As a group, non-conventional dysplasia was predominantly found in patients with ulcerative colitis [UC] [n = 68; 70%] and occurred in the left colon [n = 80; 63%]; however, hypermucinous dysplasia [57%] was the least frequently associated with UC compared with goblet cell-deficient [74%] and crypt cell [89%] dysplasias [p = 0.016]. Fifty [52%] patients had a history of conventional dysplasia, detected in the same colonic segment as non-conventional dysplasia at a rate of 33%. Goblet cell-deficient dysplasia [74%] was more frequently associated with conventional dysplasia than hypermucinous [43%] and crypt cell [48%] dysplasias [p = 0.044]. While hypermucinous dysplasia often had a polypoid appearance [58%], crypt cell [96%] and goblet cell-deficient [65%] dysplasias were more likely to present as flat/invisible lesions [p < 0.001]. Most lesions were low-grade [87%] at diagnosis, but goblet cell-deficient dysplasia [31%] more often showed high-grade dysplasia [HGD] compared with hypermucinous [15%] and crypt cell [0%] dysplasias [p = 0.003]. Hypermucinous dysplasia usually demonstrated a tubulovillous/villous architecture [76%], whereas goblet cell-deficient dysplasia was predominantly tubular [92%]. A flat architecture was exclusively associated with crypt cell dysplasia [100%] [p < 0.001]. Immunohistochemical stain results for p53 were available for 33 lesions; 14 [42%] showed strong [3+] and patchy [10-50%] to diffuse [>50%] nuclear overexpression or null staining pattern, including four [33%] of 12 hypermucinous, two [29%] of seven goblet cell-deficient and eight [57%] of 14 crypt cell dysplastic lesions [p = 0.726]. Follow-up biopsies or resections were available for 92 low-grade lesions from 71 patients; 55 [60%] lesions, including 19 [49%] of 39 hypermucinous, 10 [59%] of 17 goblet cell-deficient and 26 [72%] of 36 crypt cell dysplastic lesions [p = 0.116], were associated with subsequent detection of HGD [n = 34; 37%] or adenocarcinoma [n = 21; 23%] at the site of previous biopsy or in the same colonic segment within a mean follow-up time of 12 months [range: <1-73]. CONCLUSIONS: Hypermucinous, goblet cell-deficient and crypt cell dysplasias have distinct clinicopathological features but appear to have a similar high risk of association with advanced neoplasia [HGD or adenocarcinoma]. More than half of the lesions [66%] presented as flat/invisible dysplasia, suggesting that IBD patients may benefit from random biopsy sampling in addition to targeted biopsies. Although not uncommonly associated with conventional dysplasia, non-conventional dysplasia may be the only dysplastic subtype identified in IBD patients. Therefore, it is important to recognize these non-conventional subtypes and recommend complete removal and/or careful examination and follow-up.

FGFR2-IIIb Expression by Immunohistochemistry Has High Specificity in Cholangiocarcinoma with FGFR2 Genomic Alterations.

BACKGROUND: FGFR2 genomic alterations are observed in 10-20% of cholangiocarcinoma (CCA). Although FGFR2 fusions are an important actionable target, FGFR2 protein expression has not been thoroughly characterized. AIMS: To evaluate FGFR2 protein expression in cholangiocarcinoma harboring FGFR2 genomic alterations. METHODS: FGFR2 protein expression was evaluated in 99 CCA cases with two different antibodies. FGFR2 genomic alterations were confirmed via next-generating sequencing (NGS) or FISH. Primary objective was to determine the specificity and sensitivity of FGFR2 immunohistochemistry staining for detecting FGFR2 genomic alterations. Secondary objectives included overall FGFR2 immunohistochemistry staining in CCA patients, and evaluation of whether FGFR2 expression correlates with clinical outcomes including overall survival (OS), progression-free survival (PFS), and time-to-tumor recurrence (TTR). RESULTS: Immunohistochemistry staining with two antibodies against FGFR2, FPR2-D, and clone 98706 showed high accuracy (78.7% and 91.9%) and specificity (82.9% and 97.7%), and moderate sensitivity (53.9% and 57.1%), respectively, when compared with the standard methods for detecting FGFR2 genomic alterations. In a median follow-up of 72 months, there were no statistically significant differences in OS, PFS, and TTR, for patients with positive or negative FGFR2 staining. CONCLUSION: FGFR2 protein expression by immunohistochemistry has high specificity and therefore could be used to imply the presence of FGFR2 genomic alterations in the context of a positive test. In the case of a negative test, NGS or FISH would be necessary to ascertain cases with FGFR2 genomic alterations.

Treatment of Ruptured and Nonruptured Aneurysms Using a Semisolid Iodinated Embolic Agent.

Saccular aneurysms (SAs) are focal outpouchings from the lateral wall of an artery. Depending on their morphology and location, minimally invasive treatment options include coil embolization, flow diverter stents, stent-assisted coiling, and liquid embolics. Many drawbacks are associated with these treatment options including recanalization, delayed healing, rebleeding, malpositioning of the embolic or stent, stent stenosis, and even rupture of the SA. To overcome these drawbacks, a nanoclay-based shear-thinning hydrogel (STH) is developed for the endovascular treatment of SAs. Extensive in vitro testing is performed to optimize STH performance, visualization, injectability, and endothelialization in cell culture. Femoral artery saccular aneurysm models in rats and in pigs are created to test stability, efficacy, immune response, endothelialization, and biocompatibility of STH in both ruptured and unruptured SA. Fluoroscopy and computed tomography imaging consistently confirmed SA occlusion without recanalization, migration, or nontarget embolization; STH is also shown to outperform coil embolization of porcine aneurysms. In pigs with catastrophic bleeding due to SA rupture, STH is able to achieve instant hemostasis rescuing the pigs in long-term survival experiments. STH is a promising semisolid iodinated embolic agent that can change the standard of medical practice and potentially save lives.

Amyloidosis: Multisystem Spectrum of Disease with Pathologic Correlation.

Amyloidosis is a group of conditions defined by extracellular deposition of insoluble proteins that can lead to multiorgan dysfunction and failure. The systemic form of the disease is often associated with a plasma cell dyscrasia but may also occur in the setting of chronic inflammation, long-term dialysis, malignancy, or multiple hereditary conditions. Localized forms of the disease most often involve the skin, tracheobronchial tree, and urinary tract and typically require tissue sampling for diagnosis, as they may mimic many conditions including malignancy at imaging alone. Advancements in MRI and nuclear medicine have provided greater specificity for the diagnosis of amyloidosis involving the central nervous system and heart, potentially obviating the need for biopsy of the affected organ in certain circumstances. Specifically, a combination of characteristic findings at noninvasive cardiac MRI and skeletal scintigraphy in patients without an underlying plasma cell dyscrasia is diagnostic for cardiac transthyretin amyloidosis. Histologically, the presence of amyloid is denoted by staining with Congo red and a characteristic apple green birefringence under polarized light microscopy. The imaging features of amyloid vary across each organ system but share some common patterns, such as soft-tissue infiltration and calcification, that may suggest the diagnosis in the appropriate clinical context. The availability of novel therapeutics that target amyloid protein fibrils such as transthyretin highlights the importance of early diagnosis. Online supplemental material is available for this article. ©RSNA, 2021.

Zonation in NASH - A key paradigm for understanding pathophysiology and clinical outcomes.

Non-alcoholic fatty liver disease (NAFLD) exists as a spectrum ranging from simple steatosis to histologically defined hepatocyte injury and inflammatory changes that define steatohepatitis (NASH), and increase risk for fibrosis. Although zonal differences in NASH have not been systematically studied, periportal involvement has been associated with worse metabolic outcomes and more hepatic fibrosis as compared to pericentral disease. These data suggest that hepatic zonation of disease may influence the diversity of clinical presentations. Similarly, several randomized clinical trials suggest a differential response based on zonation of disease, with preferential effects on periportal (cysteamine) or pericentral disease (obeticholic acid, pioglitazone). Intriguingly, morphogenic pathways known to affect zonal development and maintenance - WNT/ß-Catenin, Hedgehog, HIPPO/Yap/TAZ and Notch - have been implicated in NASH pathogenesis, and nuclear hormone receptors downstream of potential NASH therapeutics show zonal preferences. In this review, we summarize these data and propose that patient-specific activation of these pathways may explain the variability in clinical presentation, and the zone-specific response observed in clinical trials.

Cytomegalovirus haemorrhagic enterocolitis associated with severe infection with COVID-19.

We present a case of haemorrhagic enterocolitis in a patient with SARS-CoV-2 who recovered from respiratory failure after support with venovenous extracorporeal membrane oxygenation. We describe clinicopathological features consistent with the systemic coinfection/reactivation of cytomegalovirus (CMV) concurrent with COVID-19 infection and the protracted clinical course of resolution of gastrointestinal inflammation after the treatment of CMV infection. Stool PCR, abdominal CT perfusion scan and histological examination of ileal and colonic tissues excluded enterocolitis secondary to other causes of infection (common viral, bacterial and protozoal gastrointestinal pathogens), macrovascularand microvascular ischaemia and classic inflammatory bowel disease, respectively. We propose possible synergistic pathophysiologic mechanisms for enterocolitis complicating severe COVID-19 infection: (1) T lymphocyte depletion and immune response dysregulation, (2) use of immunomodulators in the management of severe COVID-19 infection and (3) high concentration of ACE-2 receptors for COVID-19 virus in the gastrointestinal tract.

Interobserver agreement and the impact of mentorship on the diagnosis of inflammatory bowel disease-associated dysplasia among subspecialist gastrointestinal pathologists.

The diagnosis of inflammatory bowel disease (IBD)-associated dysplasia is challenging, and past studies have demonstrated considerable interobserver variability in such diagnoses. This study aimed to assess interobserver agreement in IBD dysplasia diagnoses among subspecialty GI pathologists and to explore the impact of mentorship on diagnostic variability. Twelve GI pathologist mentees and 7 GI pathologist mentors reviewed 163 digitized slides. Participants rendered a diagnosis of negative for dysplasia, indefinite for dysplasia, low-grade dysplasia, or high-grade dysplasia and provided a confidence level for each case. Interobserver agreement and reliability were assessed using Cohen's and Fleiss' kappa (κ) statistics and intraclass correlation coefficient (ICC) analysis. The overall κ coefficient was 0.42 (95% CI: 0.38-0.46). The overall ICC was 0.67 (95% CI: 0.62-0.72). Κ coefficients ranged from 0.31 to 0.49 for mentor/mentee pairs and from 0.34 to 0.55 for pairs of mentees of the same mentor. The combined κ coefficient was 0.44 (95% CI: 0.39-0.48) for all mentees and 0.39 (95% CI: 0.34-0.43) for all mentors. Common features in low agreement cases included mucosal atrophy, areas of stark contrast, serrations, decreased goblet cells, absent surface epithelium, and poor orientation. Participants were confident in most diagnoses, and increased confidence levels generally correlated with higher interobserver agreement. Interobserver agreement among subspecialist GI pathologists in this curated cohort of IBD dysplasia cases was fair to moderate. Mentorship during GI pathology fellowship does not appear to be a significant factor contributing to interobserver variability, but increased experience also does not seem to improve interobserver agreement.

Notch activity characterizes a common hepatocellular carcinoma subtype with unique molecular and clinicopathologic features.

BACKGROUND & AIMS: The hepatocyte Notch pathway is a pathogenic factor in non-alcoholic steatohepatitis (NASH)-associated fibrosis, but its role in hepatocellular carcinoma (HCC) is less well defined. Herein, we aimed to characterize the molecular and clinical features of Notch-active human HCC, and to investigate the mechanisms by which Notch affects NASH-driven HCC. METHODS: Using a 14-gene Notch score, we stratified human HCCs from multiple comprehensively profiled datasets. We performed gene set enrichment analyses to compare Notch-active HCCs with published HCC subtype signatures. Next, we sorted Notch-active hepatocytes from Notch reporter mice for RNA sequencing and characterized Notch-active tumors in an HCC model combining a carcinogen and a NASH-inducing diet. We used genetic mouse models to manipulate hepatocyte Notch to investigate the sufficiency and necessity of Notch in NASH-driven tumorigenesis. RESULTS: Notch-active signatures were found in ~30% of human HCCs that transcriptionally resemble cholangiocarcinoma-like HCC, exhibiting a lack of activating CTNNB1 (ß-catenin) mutations and a generally poor prognosis. Endogenous Notch activation in hepatocytes is associated with repressed ß-catenin signaling and hepatic metabolic functions, in lieu of increased interactions with the extracellular matrix in NASH. Constitutive hepatocyte Notch activation is sufficient to induce ß-catenin-inactive HCC in mice with NASH. Notch and ß-catenin show a pattern of mutual exclusivity in carcinogen-induced HCC; in this mouse model, chronic blockade of Notch led to ß-catenin-dependent tumor development. CONCLUSIONS: Notch activity characterizes a distinct HCC molecular subtype with unique histology and prognosis. Sustained Notch signaling in chronic liver diseases can drive tumor formation without acquiring specific genomic driver mutations. LAY SUMMARY: The Notch signaling pathway is known to be involved in the pathogenesis of liver fibrosis. However, its role in liver cancer has not been well defined. Herein, we show that Notch activity is increased in a subset of liver cancers and is associated with poor outcomes. We also used a mouse model to show that aberrant Notch activity can drive cancer progression in obese mice.