Improved assessment of donor liver steatosis using Banff consensus recommendations and deep learning algorithms

BACKGROUND & AIMS

The Banff Liver Working Group recently published consensus recommendations for steatosis assessment in donor liver biopsy, but few studies reported their use and no automated deep-learning algorithms based on the proposed criteria have been developed so far. We evaluated Banff recommendations on a large monocentric series of donor liver needle biopsies by comparing pathologists' scores with those generated by convolutional neural networks (CNNs) we specifically developed for automated steatosis assessment.

METHODS

We retrospectively retrieved 292 allograft liver needle biopsies collected between January 2016 and January 2020 and performed steatosis assessment using a former intra-institution method (pre-Banff method) and the newly introduced Banff recommendations. Scores provided by pathologists and CNN models were then compared, and the degree of agreement was measured with the intraclass correlation coefficient (ICC).

RESULTS

Regarding the pre-Banff method, poor agreement was observed between the pathologist and CNN models for small droplet macrovesicular steatosis (ICC: 0.38), large droplet macrovesicular steatosis (ICC: 0.08), and the final combined score (ICC: 0.16) evaluation, but none of these reached statistically significance. Interestingly, significantly improved agreement was observed using the Banff approach: ICC was 0.93 for the low-power score (p <0.001), 0.89 for the high-power score (p <0.001), and 0.93 for the final score (p <0.001). Comparing the pre-Banff method with the Banff approach on the same biopsy, pathologist and CNN model assessment showed a mean (±SD) percentage of discrepancy of 26.89 (±22.16) and 1.20 (±5.58), respectively.

CONCLUSIONS

Our findings support the use of Banff recommendations in daily practice and highlight the need for a granular analysis of their effect on liver transplantation outcomes.

IMPACT AND IMPLICATIONS

We developed and validated the first automated deep-learning algorithms for standardized steatosis assessment based on the Banff Liver Working Group consensus recommendations. Our algorithm provides an unbiased automated evaluation of steatosis, which will lay the groundwork for granular analysis of steatosis's short- and long-term effects on organ viability, enabling the identification of clinically relevant steatosis cut-offs for donor organ acceptance. Implementing our algorithm in daily clinical practice will allow for a more efficient and safe allocation of donor organs, improving the post-transplant outcomes of patients.

Histidine-rich glycoprotein in metabolic dysfunction-associated steatohepatitis-related disease progression and liver carcinogenesis

Background

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously non-alcoholic fatty liver disease (NAFLD), is a leading cause of chronic liver disease worldwide. In 20%-30% of MASLD patients, the disease progresses to metabolic dysfunction-associated steatohepatitis (MASH, previously NASH) which can lead to fibrosis/cirrhosis, liver failure as well as hepatocellular carcinoma (HCC). Here we investigated the role of histidine-rich glycoprotein (HRG), a plasma protein produced by hepatocytes, in MASLD/MASH progression and HCC development.

Methods

The role of HRG was investigated by morphological, cellular, and molecular biology approaches in (a) HRG knock-out mice (HRG-/- mice) fed on a CDAA dietary protocol or a MASH related diethyl-nitrosamine/CDAA protocol of hepatocarcinogenesis, (b) THP1 monocytic cells treated with purified HRG, and (c) well-characterized cohorts of MASLD patients with or without HCC.

Results

In non-neoplastic settings, murine and clinical data indicate that HRG increases significantly in parallel with disease progression. In particular, in MASLD/MASH patients, higher levels of HRG plasma levels were detected in subjects with extensive fibrosis/cirrhosis. When submitted to the pro-carcinogenic protocol, HRG-/- mice showed a significant decrease in the volume and number of HCC nodules in relation to decreased infiltration of macrophages producing pro-inflammatory mediators, including IL-1β, IL-6, IL-12, IL-10, and VEGF as well as impaired angiogenesis. The histopathological analysis (H-score) of MASH-related HCC indicate that the higher HRG positivity in peritumoral tissue significantly correlates with a lower overall patient survival and an increased recurrence. Moreover, a significant increase in HRG plasma levels was detected in cirrhotic (F4) patients and in patients carrying HCC vs. F0/F1 patients.

Conclusion

Murine and clinical data indicate that HRG plays a significant role in MASLD/MASH progression to HCC by supporting a specific population of tumor-associated macrophages with pro-inflammatory response and pro-angiogenetic capabilities which critically support cancer cell survival. Furthermore, our data suggest HRG as a possible prognostic predictor in HCC patients with MASLD/MASH-related HCCs.

HER2-low in gastro-oesophageal adenocarcinoma: a real-world pathological perspective

AIMS

In the DESTINY-Gastric01 trial, a novel HER2-targeted antibody-drug conjugate trastuzumab deruxtecan proved to be effective in HER2-low gastro-oesophageal adenocarcinomas. The aim of our study is to investigate the clinicopathological and molecular features of HER2-low gastric/gastro-oesophageal junction cancers in the real-world setting of a large multi-Institutional series.

METHODS

We retrospectively evaluated 1210 formalin-fixed paraffin-embedded samples of gastro-oesophageal adenocarcinomas which were analysed by immunohistochemistry for HER2 protein expression in 8 Italian surgical pathology units from January 2018 to June 2022. We assessed the prevalence of HER2-low (ie, HER2 1+ and HER2 2+ without amplification) and its correlation with clinical and histopathological features, other biomarkers' status, including mismatch repair/microsatellite instability status, Epstein-Barr encoding region (EBER) and PD-L1 Combined Positive Score.

RESULTS

HER2 status could be assessed in 1189/1210 cases, including 710 HER2 0 cases, 217 HER2 1+, 120 not amplified HER2 2+, 41 amplified HER2 2+ and 101 HER2 3+. The estimated prevalence of HER2-low was 28.3% (95% CI 25.8% to 31.0%) overall, and was higher in biopsy specimens (34.9%, 95% CI 31.2% to 38.8%) compared with surgical resection specimens (21.0%, 95% CI 17.7% to 24.6%) (p<0.0001). Moreover, HER2-low prevalence ranged from 19.1% to 40.6% among centres (p=0.0005).

CONCLUSIONS

This work shows how the expansion of the HER2 spectrum might raise problems in reproducibility, especially in biopsy specimens, decreasing interlaboratory and interobserver concordance. If controlled trials confirm the promising activity of novel anti-HER2 agents in HER2-low gastro-oesophageal cancers, a shift in the interpretation of HER2 status may need to be pursued.

Evaluating mismatch repair deficiency in colorectal cancer biopsy specimens

Mismatch repair (MMR) testing on all new cases of colorectal cancer (CRC) has customarily been preferably performed on surgical specimens, as more tissue is available; however, new clinical trials for the use of immune checkpoint inhibitors in the neoadjuvant setting require MMR testing on biopsy samples. This study aims at identifying advantages, disadvantages and any potential pitfalls in MMR evaluation on biopsy tissue and how to cope with them. The study is prospective-retrospective, recruiting 141 biopsies (86 proficient (p)MMR and 55 deficient (d)MMR) and 97 paired surgical specimens (48 pMMR; 49 dMMR). In biopsy specimens, a high number of indeterminate stains was observed, in particular for MLH1 (31 cases, 56.4%). The main reasons were a punctate nuclear expression of MLH1, relatively weak MLH1 nuclear expression compared to internal controls, or both (making MLH1 loss difficult to interpret), which was solved by reducing primary incubation times for MLH1. A mean of  ≥ 5 biopsies had adequate immunostains, compared to ≤ 3 biopsies in inadequate cases. Conversely, surgical specimens rarely suffered from indeterminate reactions, while weaker staining intensity (p < 0.007) for MLH1 and PMS2 and increased patchiness grade (p < 0.0001) were seen. Central artefacts were almost exclusive to surgical specimens. MMR status classification was possible in 92/97 matched biopsy/resection specimen cases, and all of these were concordant (47 pMMR and 45 dMMR). Evaluation of MMR status on CRC biopsy samples is feasible, if pitfalls in interpretation are known, making laboratory-specific appropriate staining protocols fundamental for high-quality diagnoses.

Low PD-L1 expression in immune cells predicts the presence of nodal metastasis in early invasive (pT1) colorectal cancer: a novel tool to tailor surgical treatment

AIMS

The current criteria for surgical treatment after endoscopic resection of a pT1 colorectal carcinoma (CRC) are unsatisfactory because nodal involvement is rarely present. This study investigates the correlation between PD-L1 expression and nodal metastasis in pT1 CRCs to enable its use for tailoring surgical treatment after endoscopic removal.

METHODS AND RESULTS

Histopathological features of 81 surgically resected pT1 CRC, 19 metastatic and 62 non-metastatic cases were assessed. PD-L1 expression was evaluated by immunohistochemistry (clone 22C3) and independently assessed by two pathologists using tumour proportion score (TPS), combined positive score (CPS) and immune cell score (ICS). The correlation between PD-L1 expression and nodal metastasis, the optimal cut-off values, interobserver agreement and impact upon patients' surgical management were determined. PD-L1 expression in terms of CPS and ICS independently correlated with lymph node metastasis (PD-L1_CPS : OR = -2.5, 95% CI = -4.11 to -0.97, P = 0.008 and PD-L1_ICS : OR = -1.85, 95% CI = -2.90 to -0.79, P = 0.004) and < 1.2 CPS and <1.3% ICS were identified as the optimal cut-off values to discriminate between metastatic and non-metastatic patients. In our cohort, the implementation of these cut-off values would have avoided a significant rate of unnecessary surgeries in pN0 patients (PD-L1_CPS  = 43.2; PD-L1_ICS  = 51.9%). Ultimately, PD-L1 evaluation showed good interpathologist concordance in absolute terms [PD-L1_CPS interclass correlation coefficient (ICC) = 0.91; PD-L1_ICS ICC = 0.793] and using the identified cut-off values (PD-L1_CPS ICC = 0.848; PD-L1_ICS ICC = 0.756).

CONCLUSIONS

Our study shows that PD-L1 expression is an effective predictor of nodal status and could improve patient selection for surgery after endoscopic removal of pT1 CRCs.

Counting mitoses in gastrointestinal stromal tumours (GISTs): variable practices in the real-world setting and their clinical implications

Mitotic count (MC) is an important prognostic indicator in gastrointestinal stromal tumours (GISTs). Though MC evaluation was initially proposed in 50 HPFs, recent international guidelines recommend that MC be performed on 5 mm² because HPFs may have different areas depending on the ocular field number (FN) of the utilized light microscope. Performing MC on different areas leads to a non-standardized evaluation and erroneous risk stratification. The aim of the study was to audit real-life MC practices with special emphasis on possible risk stratification errors. A survey was administered to Italian pathologists to evaluate the following: method used for MC (5 mm² versus 50 HPF); FN of the light microscope; prognostic scheme for risk stratification. Based on the results of the survey, 100 GISTs (25/risk class using Miettinen prognostic scheme) were retrieved and MC performed using 5 mm² versus the corresponding mm² area sizes of 50 HPFs with variable FNs (18, 20, 22). The survey demonstrated that the majority of pathologists (64.5%) use 50 HPFs with various FNs leading to excessive area size. The most frequently used prognostic scheme is that by Miettinen. Using this prognostic scheme and counting mitoses in 5 mm² versus 50 HPFs with FNs 18, 20 and 22, a change in risk class was identified ranging from 10 to 41%, depending on FN. In conclusion, this study demonstrates that MC is still frequently performed on 50 HPF, with area sizes exceeding the specified 5 mm² by far.

Next-generation pathology detection of T cell-antigen-presenting cell immune synapses in human liver allografts

BACKGROUND AND AIMS

In otherwise near-normal appearing biopsies by routine light microscopy, next-generation pathology (NGP) detected close pairings (immune pairs; iPAIRs) between lymphocytes and antigen-presenting cells (APCs) that predicted immunosuppression weaning failure in pediatric liver transplant (LTx) recipients (Immunosuppression Withdrawal for Stable Pediatric Liver Transplant Recipients [iWITH], NCT01638559). We hypothesized that NGP-detected iPAIRs enrich for true immune synapses, as determined by nuclear shape metrics, intercellular distances, and supramolecular activation complex (SMAC) formation.

APPROACH AND RESULTS

Intralobular iPAIRs (CD45 high lymphocyte-major histocompatibility complex II + APC pairs; n = 1167, training set) were identified at low resolution from multiplex immunohistochemistry-stained liver biopsy slides from several multicenter LTx immunosuppression titration clinical trials (iWITH; NCT02474199 (Donor Alloantigen Reactive Tregs (darTregs) for Calcineurin Inhibitor (CNI) Reduction (ARTEMIS); Prospective Longitudinal Study of iWITH Screen Failures Secondary to Histopathology). After excluding complex multicellular aggregates, high-resolution imaging was used to examine immune synapse formation ( n = 998). By enriching for close intranuclear lymphocyte-APC distance (mean: 0.713 μm) and lymphocyte nuclear flattening (mean ferret diameter: 2.1), SMAC formation was detected in 29% of iPAIR-engaged versus 9.5% of unpaired lymphocytes. Integration of these morphometrics enhanced NGP detection of immune synapses (ai-iSYN). Using iWITH preweaning biopsies from eligible patients ( n = 53; 18 tolerant, 35 nontolerant; testing set), ai-iSYN accurately predicted (87.3% accuracy vs. 81.4% for iPAIRs; 100% sensitivity, 75% specificity) immunosuppression weaning failure. This confirmed the presence and importance of intralobular immune synapse formation in liver allografts. Stratification of biopsy mRNA expression data by immune synapse quantity yielded the top 20 genes involved in T cell activation and immune synapse formation and stability.

CONCLUSIONS

NGP-detected immune synapses (subpathological rejection) in LTx patients prior to immunosuppression reduction suggests that NGP-detected (allo)immune activity usefulness for titration of immunosuppressive therapy in various settings.

The Landscape of HNF1B Deficiency: A Syndrome Not Yet Fully Explored

The hepatocyte nuclear factor 1β (HNF1B) gene is involved in the development of specialized epithelia of several organs during the early and late phases of embryogenesis, performing its function mainly by regulating the cell cycle and apoptosis pathways. The first pathogenic variant of HNF1B (namely, R177X) was reported in 1997 and is associated with the maturity-onset diabetes of the young. Since then, more than 230 different HNF1B variants have been reported, revealing a multifaceted syndrome with complex and heterogenous genetic, pathologic, and clinical profiles, mainly affecting the pediatric population. The pancreas and kidneys are the most frequently affected organs, resulting in diabetes, renal cysts, and a decrease in renal function, leading, in 2001, to the definition of HNF1B deficiency syndrome, including renal cysts and diabetes. However, several other organs and systems have since emerged as being affected by HNF1B defect, while diabetes and renal cysts are not always present. Especially, liver involvement has generally been overlooked but recently emerged as particularly relevant (mostly showing chronically elevated liver enzymes) and with a putative relation with tumor development, thus requiring a more granular analysis. Nowadays, HNF1B-associated disease has been recognized as a clinical entity with a broader and more variable multisystem phenotype, but the reasons for the phenotypic heterogeneity are still poorly understood. In this review, we aimed to describe the multifaceted nature of HNF1B deficiency in the pediatric and adult populations: we analyzed the genetic, phenotypic, and clinical features of this complex and misdiagnosed syndrome, covering the most frequent, unusual, and recently identified traits.

FISH Diagnostic Assessment of MDM2 Amplification in Liposarcoma: Potential Pitfalls and Troubleshooting Recommendations

MDM2 amplification represents the leading oncogenic pathway and diagnostic hallmark of liposarcoma, whose assessment is based on Fluorescence In Situ Hybridization (FISH) analysis. Despite its diagnostic relevance, no univocal interpretation criteria regarding FISH assessments of MDM2 amplification have been established so far, leading to several different approaches and potential diagnostic misinterpretations. This study aims to address the most common issues and proposes troubleshooting guidelines for MDM2 amplification assessments by FISH. We retrospectively retrieved 51 liposarcomas, 25 Lipomas, 5 Spindle Cell Lipoma/Pleomorphic Lipomas, and 2 Atypical Spindle Cell Lipomatous Tumors and the corresponding MDM2 FISH analysis. We observed MDM2 amplification in liposarcomas cases only (43 out of 51 cases) and identified three MDM2-amplified patterns (scattered (50% of cases), clustered (14% of cases), and mixed (36% of cases)) and two nonamplified patterns (low number of signals (82% of cases) and polysomic (18% of cases)). Based on these data and published evidence in the literature, we propose a set of criteria to guide MDM2 amplification analysis in liposarcoma. Kindled by the compelling importance of MDM2 assessments to improve diagnostic and therapeutic liposarcoma management, these suggestions could represent the first step to develop a univocal interpretation model and consensus guidelines.

New case of syncytial giant-cell variant of hepatocellular carcinoma in a pediatric patient with HNF1B deficiency: does it fit with the syndrome?

BACKGROUND

Hepatocyte nuclear factor 1B (HNF1B) is a member of the homeodomain-containing family of transcription factors located on 17q12. HNF1B deficiency is associated with a clinical syndrome (kidney and urogenital malformations, maturity-onset diabetes of the young, exocrine pancreatic insufficiency) and to an underdiagnosed liver involvement. Differently from HNF1A, the correlation between hepatocellular carcinoma (HCC) and germline HNF1B deficiency has been poorly evaluated.

CASE REPORT

Here, we report a novel case of a syndromic HNF1B-deficient paediatric patient that developed HCC with unique histopathological features characterised by neoplastic syncytial giant cells, which was observed only in one additional case of paediatric cholestatic liver disease of unknown origin.

CONCLUSIONS

Our case highlights the influence of HNF1B deficiency in liver disease progression and its putative association with a rare yet specific HCC histotype. We hypothesised that HCC could be secondary to the repressive effect of HNF1B variant on the HNF1A transcriptional activity.

Is there life on the airway tree? A pilot study of bronchial cell vitality and tissue morphology in the ex vivo lung perfusion (EVLP) era of lung transplantation

BACKGROUND

Ex vivo lung perfusion (EVLP) is a relevant procedure to increase the lung donor pool but could potentially increase the airway tree ischemic injury risk.

METHODS

This study aimed to evaluate the direct effect of EVLP on the airway tree by evaluating bronchial cell vitality and tissue signs of injury on a series of 117 bronchial rings collected from 40 conventional and 19 EVLP-treated lung grafts. Bronchial rings and related scraped bronchial epithelial cells were collected before the EVLP procedure and surgical anastomosis.

RESULTS

The preimplantation interval was significantly increased in the EVLP graft group (p < 0.01). Conventional grafts presented cell viability percentages of 47.07 ± 23.41 and 49.65 ± 21.25 in the first and second grafts which did not differ significantly from the EVLP group (first graft 50.54 ± 25.83 and second graft 50.22 ± 20.90 cell viability percentage). No significant differences in terms of histopathological features (edema, inflammatory infiltrate, and mucosa ulceration) were observed comparing conventional and EVLP samples. A comparison of bronchial cell viability and histopathology of EVLP samples retrieved at different time intervals revealed no significant differences. Accordingly, major bronchial complications after lung transplant were not observed in both groups.

CONCLUSIONS

Based on these data, we observed that EVLP did not significantly impact bronchial cell vitality and airway tissue preservation nor interfere with bronchial anastomosis healing, further supporting it as a safe and useful procedure.

Viability assessment and transplantation of fatty liver grafts using end-ischemic normothermic machine perfusion

End-ischemic viability testing by normothermic machine perfusion (NMP) represents an effective strategy to recover liver grafts having initially been discarded for liver transplantation (LT). However, its results in the setting of significant (≥30%) macrovesicular steatosis (MaS) have not been specifically assessed. Prospectively maintained databases at two high-volume LT centers in Northern Italy were searched to identify cases of end-ischemic NMP performed to test the viability of livers with MaS ≥ 30% in the period from January 2019 to January 2022. A total of 14 cases were retrieved, representing 57.9% of NMP and 5.7% of all machine perfusion procedures. Of those patients, 10 (71%) received transplants. Two patients developed primary nonfunction (PNF) and required urgent re-LT, and both were characterized by incomplete or suboptimal lactate clearance during NMP. PNF cases were also characterized by higher perfusate transaminases, lower hepatic artery and portal vein flows at 2 h, and a lack of glucose metabolism in one case. The remaining eight patients showed good liver function (Liver Graft Assessment Following Transplantation risk score, -1.9 [risk, 13.6%]; Early Allograft Failure Simplified Estimation score, -3.7 [risk, 2.6%]) and had a favorable postoperative course. Overall, NMP allowed successful transplantation of 57% of livers with moderate-to-severe MaS. Our findings suggest that prolonged observation (≥6 h) might be required for steatotic livers and that stable lactate clearance is a fundamental prerequisite for their use.

DNAJB9 Is a Reliable Immunohistochemical Marker of Fibrillary Glomerulonephritis: Evaluation of Diagnostic Efficacy in a Large Series of Kidney Biopsies

Fibrillary glomerulonephritis (FGN) is a rare glomerular disease characterized by a challenging diagnostic workup requiring ultrastructural identification of 20 nm-thick randomly oriented fibrillar deposits. However, the recent introduction of DNAJB9 as a putative diagnostic marker of FGN could thoroughly improve this diagnostic scenario. This study aims to assess the DNAJB9 immunohistochemical expression in a large series of FGN cases and to eventually confirm its role as a diagnostic marker of FGN. We evaluated the immunohistochemical expression of DNAJB9 (Rabbit Polyclonal, ThermoFisher) in a series of 77 FGN and 128 non-FGN cases diagnosed between January 1992 and June 2022 at the Pathology Unit of the AOU Città della Salute e della Scienza Hospital. DNAJB9 was expressed in 73 of the 74 evaluable FGN cases, mostly showing a strong glomerular positivity (68 cases). Additionally, DNAJB9 resulted positive in all challenging scenarios [early-stage (6), congophilic (4), combined (4), and uncertain (4) cases of FGN)]. DNAJB9 was negative in all non-FGN cases, eventually resulting in a specificity of 100% and sensitivity of 99%. In conclusion, we confirmed the role of DNAJB9 as a diagnostic marker of FGN. Its adoption in the clinical routine will allow a faster, more feasible, and more accurate FGN diagnosis.

A new ex-situ machine perfusion device. A preliminary evaluation using a model of donors after circulatory death pig livers

We herein describe a new ex-situ machine perfusion device as a "technology spotlight" using a model of donors after circulatory death liver grafts procured from slaughterhouse pigs. Fourteen pig liver grafts were included. The device allowed stable perfusion in both hypothermic (n = 6) and normothermic (n = 8) conditions and no technical failure was observed. During perfusion, perfusate and bile samples were collected to assess liver metabolism and viability. An integrated adsorption device showed efficient removal of inflammatory cytokines during treatment. This preliminary experience represents the starting point for further investigations on the potential clinical benefits of cytokines and other inflammatory mediators adsorption during machine perfusion.

Validation of a Simple, Rapid, and Cost-Effective Method for Acute Rejection Monitoring in Lung Transplant Recipients

Despite advances in immunosuppression therapy, acute rejection remains the leading cause of graft dysfunction in lung transplant recipients. Donor-derived cell-free DNA is increasingly being considered as a valuable biomarker of acute rejection in several solid organ transplants. We present a technically improved molecular method based on digital PCR that targets the mismatch between the recipient and donor at the HLA-DRB1 locus. Blood samples collected sequentially post-transplantation from a cohort of lung recipients were used to obtain proof-of-principle for the validity of the assay, correlating results with transbronchial biopsies and lung capacity tests. The results revealed an increase in dd-cfDNA during the first 2 weeks after transplantation related to ischemia-reperfusion injury (6.36 ± 5.36%, p < 0.0001). In the absence of complications, donor DNA levels stabilized, while increasing again during acute rejection episodes (7.81 ± 12.7%, p < 0.0001). Respiratory tract infections were also involved in the release of dd-cfDNA (9.14 ± 15.59%, p = 0.0004), with a positive correlation with C-reactive protein levels. Overall, the dd-cfDNA percentages were inversely correlated with the lung function values measured by spirometry. These results confirm the value of dd-cfDNA determination during post-transplant follow-up to monitor acute rejection in lung recipients, achieved using a rapid and inexpensive approach based on the HLA mismatch between donor and recipient.

Outcome of liver transplantation with grafts from brain-dead donors treated with dual hypothermic oxygenated machine perfusion, with particular reference to elderly donors

Prompted by the utilization of extended criteria donors, dual hypothermic oxygenated machine perfusion (D-HOPE) was introduced in liver transplantation to improve preservation. When donors after neurological determination of death (DBD) are used, D-HOPE effect on graft outcomes is unclear. To assess D-HOPE value in this setting and to identify ideal scenarios for its use, data on primary adult liver transplant recipients from January 2014 to April 2021 were analyzed using inverse probability of treatment weighting, comparing outcomes of D-HOPE-treated grafts (n = 121) with those preserved by static cold storage (n = 723). End-ischemic D-HOPE was systematically applied since November 2017 based on donor and recipient characteristics and transplant logistics. D-HOPE use was associated with a significant reduction of early allograft failure (OR: 0.24; 0.83; p = .024), grade ≥3 complications (OR: 0.57; p = .046), comprehensive complication index (-7.20 points; p = .003), and improved patient and graft survival. These results were confirmed in the subset of elderly donors (>75-year-old). Although D-HOPE did not reduce the incidence of biliary complications, its use was associated with a reduced severity of ischemic cholangiopathy. In conclusion, D-HOPE improves postoperative outcomes and reduces early allograft loss in extended criteria DBD grafts.

Not only a small liver - The pathologist's perspective in the pediatric liver transplant setting

Pediatric liver transplantation represents a safe and long-lasting treatment option for various disease types, requiring the pathologist’s input. Indeed, an accurate and timely diagnosis is crucial in reporting and grading native liver diseases, evaluating donor liver eligibility and identifying signs of organ injury in the post-transplant follow-up. However, as the procedure is more frequently and widely performed, deceptive and unexplored histopathologic features have emerged with relevant consequences on patient management, particularly when dealing with long-term treatment and weaning of immunosuppression.

In this complex and challenging scenario, this review aims to depict the most relevant histopathologic conditions which could be encountered in pediatric liver transplantation. We will tackle the conditions representing the main indications for transplantation in childhood as well as the complications burdening the post-transplant phases, either immunologically (i.e., rejection) or non-immunologically mediated. Lastly, we hope to provide concise, yet significant, suggestions related to innovative pathology techniques in pediatric liver transplantation.

The Importance of Being “That” Colorectal pT1: A Combined Clinico-Pathological Predictive Score to Improve Nodal Risk Stratification

The management of endoscopically resected pT1 colorectal cancer (CRC) relies on nodal metastasis risk estimation based on the assessment of specific histopathological features. Avoiding the overtreatment of metastasis-free patients represents a crucial unmet clinical need. By analyzing a consecutive series of 207 pT1 CRCs treated with colectomy and lymphadenectomy, this study aimed to develop a novel clinicopathological score to improve pT1 CRC metastasis prediction. First, we established the clinicopathological profile of metastatic cases: lymphovascular invasion (OR: 23.8; CI: 5.12–110.9) and high-grade tumor budding (OR: 5.21; CI: 1.60–16.8) correlated with an increased risk of nodal metastasis, while age at diagnosis >65 years (OR: 0.26; CI: 0.09–0.71) and high tumor-infiltrating lymphocytes (OR: 0.19; CI: 0.06–0.59) showed a protective effect. Combining these features, we built a five-tier risk score that, applied to our series, identified cases with a higher risk (score ≥ 2) of nodal metastasis (OR: 7.7; CI: 2.4–24.4). Notably, a score of 0 was only assigned to cases with no metastases (13/13 cases) and all the score 4 samples (2/2 cases) showed nodal metastases. In conclusion, we developed an effectively combined score to assess pT1 CRC nodal metastasis risk. We believe that its adoption within a multidisciplinary pT1 unit could improve patients' clinical management and limit surgical overtreatment.

Spectrum of Kidney Injury Following COVID-19 Disease: Renal Biopsy Findings in a Single Italian Pathology Service

The onset of coronavirus disease (COVID-19) as a pandemic infection, has led to increasing insights on its pathophysiology and clinical features being revealed, such as a noticeable kidney involvement. In this study, we describe the histopathological, immunofluorescence, and ultrastructural features of biopsy-proven kidney injury observed in a series of SARS-CoV-2 positive cases in our institution from April 2020 to November 2021. We retrieved and retrospectively reviewed nine cases (two pediatric and seven adults) that experienced nephrotic syndrome (six cases), acute kidney injury (two cases), and a clinically silent microhematuria and leukocyturia. Kidney biopsies were investigated by means of light microscopy, direct immunofluorescence, and electron microscopy. The primary diagnoses were minimal change disease (four cases), acute tubular necrosis (two cases), collapsing glomerulopathy (two cases), and C3 glomerulopathy (one case). None of the cases showed viral or viral-like particles on ultrastructural analysis. Novel and specific histologic features on kidney biopsy related to SARS-CoV-2 infection have been gradually disclosed and reported, harboring relevant clinical and therapeutic implications. Recognizing and properly diagnosing renal involvement in patients experiencing COVID-19 could be challenging (due to the lack of direct proof of viral infection, e.g., viral particles) and requires a proper integration of clinical and pathological data.

Clinical assessment of liver metabolism during hypothermic oxygenated machine perfusion using microdialysis

Background

While growing evidence supports the use of hypothermic oxygenated machine perfusion (HOPE) in liver transplantation, its effects on liver metabolism are still incompletely understood.

Methods

To assess liver metabolism during HOPE using microdialysis (MD), we conducted an open‐label, observational pilot study on 10 consecutive grafts treated with dual‐HOPE (D‐HOPE). Microdialysate and perfusate levels of glucose, lactate, pyruvate, glutamate, and flavin mononucleotide (FMN) were measured during back table preparation and D‐HOPE and correlated to graft function and patient outcome.

Results

Median (IQR) MD and D‐HOPE time was 228 (210, 245) and 116 (103, 143) min. Three grafts developed early allograft dysfunction (EAD), with one requiring retransplantation. During D‐HOPE, MD glucose and lactate levels increased (ANOVA = 9.88 [p = 0.01] and 3.71 [p = 0.08]). Their 2nd‐hour levels were higher in EAD group and positively correlated with L‐GrAFT score. 2nd‐hour MD glucose and lactate were also positively correlated with cold ischemia time, macrovesicular steatosis, weight gain during D‐HOPE, and perfusate FMN. These correlations were not apparent when perfusate levels were considered. In contrast, MD FMN levels invariably dropped steeply after D‐HOPE start, whereas perfusate FMN was higher in dysfunctioning grafts.

Conclusion

MD glucose and lactate during D‐HOPE are markers of hepatocellular injury and could represent additional elements of the viability assessment.

Human liver stem cell-derived extracellular vesicles reduce injury in a model of normothermic machine perfusion of rat livers previously exposed to a prolonged warm ischemia

Livers from donors after circulatory death (DCD) are a promising option to increase the donor pool, but their use is associated with higher complication rate and inferior graft survival. Normothermic machine perfusion (NMP) keeps the graft at 37°C, providing nutrients and oxygen supply. Human liver stem cell‐derived extracellular vesicles (HLSC‐EVs) are able to reduce liver injury and promote regeneration. We investigated the efficacy of a reconditioning strategy with HLSC‐EVs in an experimental model of NMP. Following total hepatectomy, rat livers were divided into 4 groups: (i) healthy livers, (ii) warm ischemic livers (60 min of warm ischemia), (iii) warm ischemic livers treated with 5 × 10⁸ HLSC‐EVs/g‐liver, and (iv) warm ischemic livers treated with a 25 × 10⁸ HLSC‐EVs/g‐liver. NMP lasted 6 h and HLSC‐EVs (Unicyte AG, Germany) were administered within the first 15 min. Compared to controls, HLSC‐EV treatment significantly reduced transaminases release. Moreover, HLSC‐EVs enhanced liver metabolism by promoting phosphate utilization and pH self‐regulation. As compared to controls, the higher dose of HLSC‐EV was associated with significantly higher bile production and lower intrahepatic resistance. Histologically, this group showed reduced necrosis and enhanced proliferation. In conclusion, HLSC‐EV treatment during NMP was feasible and effective in reducing injury in a DCD model with prolonged warm ischemia.

Caveolin-1 expression predicts favourable outcome and correlates with PDGFRA mutations in gastrointestinal stromal tumours (GISTs)

AIMS

Novel prognostic markers are warranted for gastrointestinal stromal tumours. Caveolin-1 is a multifunctional protein that proved to be associated with outcome in multiple tumour types. Aim of this study was to investigate Caveolin-1 expression and prognostic efficacy in a series of gastrointestinal stromal tumours.

METHODS

Caveolin-1 expression was assessed by immunohistochemistry in a retrospective series of 66 gastrointestinal stromal tumours representative of the different molecular subtypes. Correlations with clinical, histopathological and molecular features were investigated. Statistical analyses were performed as appropriate.

RESULTS

Thirty-five cases out of 66 (53.0%) expressed Caveolin-1. Presence of Caveolin-1 expression correlated with favourable histopathologic and clinical traits, including a lower mitotic count (p=0.003) and lower relapse rate (p=0.005). Caveolin-1 expression also resulted associated with the presence of PDGFRA mutations (p=0.010). Outcome analyses showed a favourable prognostic significance of Caveolin-1 expression in terms of relapse-free survival (HR=0.14; 95% CI=0.03 to 0.63) and overall survival (HR=0.29; 95% CI=0.11 to 0.74), even after adjusting for the mutational subgroup (relapse-free survival: HR=0.14, 95% CI=0.04 to 0.44; overall survival: HR=0.29, 95% CI=0.11 to 0.51) and imatinib treatment (relapse-free survival: HR=0.14, 95% CI=0.02 to 0.81; overall survival: HR=0.29, 95% CI=0.17 to 0.48).

CONCLUSION

Caveolin-1 represents a novel prognostic marker in gastrointestinal stromal tumours. Further studies are warranted to validate these results and to explore the mechanisms linking Caveolin-1 expression with the PDGFRA oncogenic pathway.

Amyloid-Rich Pancreatic Neuroendocrine Tumors: a Potential Diagnostic Pitfall in Endoscopic Ultrasound-Guided Fine Needle Aspiration Cytology (EUS-FNAC)

Pancreatic neuroendocrine tumors (PanNETs) are rare neoplasms that include even rarer variants that may pose different diagnostic problems, especially in fine needle aspiration cytology (FNAC). We describe the diagnostic clues of the amyloid-rich variant of PanNETs in endoscopic ultrasound (EUS)-guided fine needle aspiration cytology (EUS-FNAC). Three cases of PanNETs with an amyloid-rich stromal component were retrieved and retrospectively reviewed. For every case, the pancreatic lesion was investigated by a EUS-FNAC procedure. The final diagnosis was supported by immunocytochemistry and Congo red staining. All cases had similar EUS-FNAC features: neoplastic cells were entrapped in an eosinophilic, homogeneous dense and amorphous matrix. The neuroendocrine nature was confirmed by immunoexpression of synaptophysin and chromogranin A, while the amorphous stroma was characterized as amyloid based on positive Congo red staining. Regarding the hormonal profile, no insulin or proinsulin reactivity was observed, but all cases were diffusely positive for amylin. The diagnosis of uncommon variants of PanNETs, such as the amyloid-rich, is challenging especially in EUS-FNAC procedures because of a unique and misleading morphology, potentially mimicking fibrotic conditions and amyloid deposition within systemic amyloidosis. In cytology specimens, the presence of amorphous material requires amyloid deposition to be considered in the differential diagnosis of pancreatic neoplasms with neuroendocrine phenotype.

HLA-DRB1 mismatch-based identification of donor-derived cell free DNA (dd-cfDNA) as a marker of rejection in heart transplant recipients: A single-institution pilot study

BACKGROUND

Donor-derived cell-free DNA (dd-cfDNA) is considered a reliable marker of organ damage with potential applications in the follow-up of transplant recipients.

METHODS

In this work we present an assay based on the donor-recipient HLA-mismatch (human leukocyte antigen) at the HLA-DRB1 locus to monitor rejection by quantifying the percentage of dd-cfDNA using a droplet digital PCR (polymerase chain reaction) technique. A panel of probes targeting the HLA-DRB1 locus and covering >85% genetic variability was validated and used to assess dd-cfDNA levels in a prospective cohort of 19 adult heart transplant recipients (mean age 50.9±14.8 years). The assay was carried out on a total of 232 liquid biopsies collected at the same time as endomyocardial biopsy (EMB) during routine post-transplant follow-up.

RESULTS

Results show a significant increase of dd-cfDNA related to ischemia-reperfusion injury (2.22±2.09%) and to acute cellular rejection (1.71±3.10%) compared to stable conditions (0.43±1.04%, p < 0.0001). On the contrary, no increase was observed during infections or vascular complications, underlining the potential role of this biomarker for rejection monitoring. With a cut-off of 0.11%, the test showed 70.8% specificity (95% CI, 58.17% - 81.40%) and 64.2% sensitivity (95% CI, 49.80% - 76.86%) in discriminating acute rejection from no rejection.

CONCLUSIONS

These data demonstrate that this HLA mismatch-based droplet digital PCR method is effective for monitoring rejection in heart transplant recipients. Compared to next generation sequencing approaches, it is far more flexible, less expensive and provides faster results.

Automated assessment of glomerulosclerosis and tubular atrophy using deep learning

In kidney transplantations, pathologists evaluate the architecture of both glomeruli, interstitium and tubules to assess the nephron status. An accurate assessment of glomerulosclerosis and tubular atrophy is crucial for determining kidney acceptance, which is currently based on the pathologists' histological evaluations on renal biopsies in addition to clinical data. In this work, we present an automated algorithm, called RENTAG (Robust EvaluatioN of Tubular Atrophy & Glomerulosclerosis), for the segmentation and classification of glomerular and tubular structures in histopathological images. The proposed novel strategy combines the accuracy of a level-set with the semantic segmentation of convolutional neural networks to detect the glomeruli and tubules contours. In the TEST set, our method exhibited excellent performance in both glomeruli (dice score: 0.9529) and tubule (dice score: 0.9174) detection and outperformed all the compared methods. To the best of our knowledge, the RENTAG algorithm is the first fully automated method capable of quantifying glomerulosclerosis and tubular atrophy in digital histological images. The developed software can be employed for the analysis of pre-transplantation biopsies to support the pathologists' diagnostic activity.

Retrospective analysis of the ultrasound features of resected thyroid nodules

PURPOSE

Several ultrasound (US) risk stratification systems (US-RSSs) have been proposed to stratify the risk of malignancy (ROM) of thyroid nodules. This risk might be overestimated due to selection bias and comparison with the cytological report alone. Our study aimed to compare ROM and diagnostic performance of three guidelines (ATA, AACE/ACE/AME, EUTIRADS) and evaluate the changes in unnecessary biopsy according to the nodule size cutoff for biopsy, using histology as gold standard.

METHODS

This retrospective observational study included 146 consecutive patients who underwent surgery after US and cytological characterization. We analyzed the effectiveness and accuracy of three US-RSSs.

RESULTS

46.6% of nodules were diagnosed as malignant. Applying US-RSS, the percentage of nodules that should have been analyzed by biopsy was 84.25% with ATA, 69.86% with EUTIRADS and 64.38% with AACE/ACE/AME systems. The ROM was 94.9%, 86.0%, 87.0% for high-risk category, 36.4%, 32.0%, 35.4% for intermediate-risk category and 22.9%, 0.0%, 22.9% for low-risk category by ATA, AACE/ACE/AME and EUTIRADS systems, respectively. EUTIRADS and AACE/ACE/AME systems were more accurate in differentiating malignant from benign cases. ATA score was the more sensitive US-RSS to identify malignant tumors within the high-risk category. About the unnecessary biopsies, in the intermediate-risk category, the application of the size criterion helps to increase specificity in all systems.

CONCLUSIONS

The US categorization of low and high-risk thyroid nodules using current US-RSSs helps alone to determine the optimal treatment option. Nodule size remains relevant to recommend biopsy for the intermediate-risk category.

A hybrid deep learning approach for gland segmentation in prostate histopathological images

BACKGROUND

In digital pathology, the morphology and architecture of prostate glands have been routinely adopted by pathologists to evaluate the presence of cancer tissue. The manual annotations are operator-dependent, error-prone and time-consuming. The automated segmentation of prostate glands can be very challenging too due to large appearance variation and serious degeneration of these histological structures.

METHOD

A new image segmentation method, called RINGS (Rapid IdentificatioN of Glandural Structures), is presented to segment prostate glands in histopathological images. We designed a novel glands segmentation strategy using a multi-channel algorithm that exploits and fuses both traditional and deep learning techniques. Specifically, the proposed approach employs a hybrid segmentation strategy based on stroma detection to accurately detect and delineate the prostate glands contours.

RESULTS

Automated results are compared with manual annotations and seven state-of-the-art techniques designed for glands segmentation. Being based on stroma segmentation, no performance degradation is observed when segmenting healthy or pathological structures. Our method is able to delineate the prostate gland of the unknown histopathological image with a dice score of 90.16 % and outperforms all the compared state-of-the-art methods.

CONCLUSIONS

To the best of our knowledge, the RINGS algorithm is the first fully automated method capable of maintaining a high sensitivity even in the presence of severe glandular degeneration. The proposed method will help to detect the prostate glands accurately and assist the pathologists to make accurate diagnosis and treatment. The developed model can be used to support prostate cancer diagnosis in polyclinics and community care centres.

Pulmonary nodular lymphoid hyperplasia in pediatric patients with Hodgkin lymphoma

Pulmonary lymphoid lesions span from benign to other forms of malignant diseases. Among these pulmonary lymphoid lesions, Nodular Lymphoid Hyperplasia (NLH) has an excellent prognosis. The surgical excision of NLH seems to be the only treatment, even if in some cases a spontaneous regression has been reported. Interestingly, these lesions may have similar clinical and radiographic presentations, making a histopathological examination vital for their differentiation. In this report we describe four cases of pediatric patients with a previous history of classical Hodgkin Lymphoma (HL) with documented or suspected NLH.

Metastatic colorectal cancer prior to expanded RAS assessment: evidence from long-term outcome analysis of a real-life cohort within a dedicated colorectal cancer unit

BACKGROUND

Molecular assessment and treatment of metastatic colorectal cancer (mCRC) quickly evolved during the last decades, hampering longitudinal evaluation of prognostic markers. The aim of this study was to evaluate prognostic predictors of long-term survival in a retrospective series of mCRC, treated prior to the expanded RAS assessment era.

METHODS

mCRC cases treated at the Città della Salute e della Scienza University Hospital (Turin, Italy) between January 2004 and December 2012 were evaluated, including cases with ≥ 5-year follow-up only. Long-term survival was defined as an overall survival (OS) ≥ 4 years based on the observed OS interquartile range values. Univariate/multivariate Cox proportional hazards regression models were performed to assess the prognostic significance of the clinical/biological features, while binary logistic regression models were used to verify their associations with long-term survival.

RESULTS

Two hundred and forty-eight mCRC cases were included and analyzed. Sixty out of two hundred and forty-eight (24%) patients were long-term survivors. Univariate binary logistic regression analysis demonstrated a significant association between long-term survival and age at diagnosis < 65 (OR = 2.28, p = 0.007), single metastatic site (OR = 1.89, p = 0.039), surgical resection of metastases (OR = 5.30, p < 0.001), local non-surgical treatment of metastases (OR = 4.74, p < 0.001), and a bevacizumab-including first-line treatment schedule (OR = 2.19, p = 0.024). Multivariate binary logistic regression analysis confirmed the prognostic significance of surgical resection of metastases (OR = 3.96, p < 0.001), local non-surgical treatment of metastases (OR = 3.32, p = 0.001), and of bevacizumab-including first-line treatment schedule (OR = 2.49, p = 0.024).

CONCLUSION

Long-term survival could be achieved in a significant rate of patients with mCRC even in an era of limited molecular characterization. Local treatment of metastases proved to be a significant predictor of long-term survival.

NTRK Fusions in Central Nervous System Tumors: A Rare, but Worthy Target

The neurotrophic tropomyosin receptor kinase (NTRK) genes (NTRK1, NTRK2, and NTRK3) code for three transmembrane high-affinity tyrosine-kinase receptors for nerve growth factors (TRK-A, TRK-B, and TRK-C) which are mainly involved in nervous system development. Loss of function alterations in these genes can lead to nervous system development problems; conversely, activating alterations harbor oncogenic potential, promoting cell proliferation/survival and tumorigenesis. Chromosomal rearrangements are the most clinically relevant alterations of pathological NTRK activation, leading to constitutionally active chimeric receptors. NTRK fusions have been detected with extremely variable frequencies in many pediatric and adult cancer types, including central nervous system (CNS) tumors. These alterations can be detected by different laboratory assays (e.g., immunohistochemistry, FISH, sequencing), but each of these approaches has specific advantages and limitations which must be taken into account for an appropriate use in diagnostics or research. Moreover, therapeutic targeting of this molecular marker recently showed extreme efficacy. Considering the overall lack of effective treatments for brain neoplasms, it is expected that detection of NTRK fusions will soon become a mainstay in the diagnostic assessment of CNS tumors, and thus in-depth knowledge regarding this topic is warranted.

Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features: From Echography to Genetic Profile

In thyroid pathology, the great variety of types and the wide range of aggressiveness of thyroid cancers complicate both diagnosis and management. In 2016, a subset of noninvasive encapsulated follicular variant of papillary thyroid carcinoma was reclassified as noninvasive follicular thyroid tumor with papillary-like nuclear features (NIFTP) to reduce overtreatment of this low-risk tumor that follows a benign course after surgery. Starting from a paradigmatic clinical case, in this short review, we will summarize the ultrasonography, cytological, histological and molecular features of this new entity. In the preoperative settings, the recognition of some peculiar elements may only suggest the possibility of a NIFTP, thus favoring a less aggressive surgical approach. However, the diagnosis of NIFTP can only be made after complete resection of the lesion by detecting well-defined inclusion and exclusion histopathological criteria. Since NIFTP is not 'malignant,' surgery may be considered curative with no further treatment or surveillance needed. NIFTP-related issues, including nodule size, multifocality, oncocytic changes, heterogeneous incidence across different geographical areas and its occurrence in the pediatric age, will be discussed.

Coping with formalin banning in pathology: under vacuum long-term tissue storage with no added formalin

Formalin is toxic and has recently been classified as carcinogenic leading to a proposed European formalin ban. But, the pathology use of formalin has however been completely overlooked, and this is proving to be a relevant issue, as no alternative, reliable, tissue fixative is available. Various systems have been proposed to reduce formalin use and exposure; long-term storage and disposal of formalin is also a problem. With this in mind, under vacuum sealing (UVS) systems have been proposed for transportation/storage, however, for how long tissue retains its characteristics (morphological and molecular) is unknown. This study aims to compare histology specimens stored by formalin immersion (FI) and specimens stored after fixation with UVS technique with no additional formalin, at different time periods. Twenty tissue samples (10FI; 10UVS) were stored for different time periods (15 days, 1-2-3-6-12 months) for a total of 120 samples, compared with regard to their morphology, histochemistry, immunoreactivity (24 specific antibodies) and DNA status. All samples showed well-preserved morphology and overlapping staining quality. A significant reduction in immunoreactivity was however identified in the various time periods, particularly for heat pre-treated nuclear antigens, and this commenced earlier (1 month) for FI. UVS storage showed higher DNA content than FI but slightly poorer DNA integrity. These results add important knowledge to the use of UVS in daily practice, as long-term storage of pre-fixed tissue in UVS is not detrimental to the quality of tissue while having the boon of using very little formalin with less operator exposure and lower disposal costs.

Quality control in diagnostic immunohistochemistry: integrated on-slide positive controls

Standardization in immunohistochemistry is a priority in modern pathology and requires strict quality control. Cost containment has also become fundamental and auditing of all procedures must take into account both these principles. Positive controls must be routinely performed so that their positivity guarantees the appropriateness of the immunohistochemical procedure. The aim of this study is to develop a low cost (utilizing a punch biopsy-PB-tool) procedure to construct positive controls which can be integrated in the patient's tissue slide. Sixteen frequently used control blocks were selected and multiple cylindrical samples were obtained using a 5-mm diameter punch biopsy tool, separately re-embedding them in single blocks. For each diagnostic immunoreaction requiring a positive control, an integrated PB-control section (cut from the appropriate PB-control block) was added to the top right corner of the diagnostic slide before immunostaining. This integrated control technique permitted a saving of 4.75% in total direct lab costs and proved to be technically feasible and reliable. Our proposal is easy to perform and within the reach of all pathology labs, requires easily available tools, its application costs is less than using external paired controls and ensures that a specific control for each slide is always available.