Histological Appearance Research Articles

Unraveling cysteine deficiency-associated rapid weight loss.

Forty percent of the US population and 1 in 6 individuals worldwide are obese, and the incidence of this disease is surging globally1,2. Various dietary interventions, including carbohydrate and fat restriction, and more recently amino acid restriction, have been explored to combat this epidemic3-6. We sought to investigate the impact of removing individual amino acids on the weight profiles of mice. Compared to essential amino acid restriction, induction of conditional cysteine restriction resulted in the most dramatic weight loss, amounting to 20% within 3 days and 30% within one week, which was readily reversed. This weight loss occurred despite the presence of substantial cysteine reserves stored in glutathione (GSH) across various tissues7. Further analysis demonstrated that the weight reduction primarily stemmed from an increase in the utilization of fat mass, while locomotion, circadian rhythm and histological appearance of multiple other tissues remained largely unaffected. Cysteine deficiency activated the integrated stress response (ISR) and NRF2-mediated oxidative stress response (OSR), which amplify each other, leading to the induction of GDF15 and FGF21, hormones associated with increased lipolysis, energy homeostasis and food aversion8-10. We additionally observed rapid tissue coenzyme A (CoA) depletion, resulting in energetically inefficient anaerobic glycolysis and TCA cycle, with sustained urinary excretion of pyruvate, orotate, citrate, α-ketoglutarate, nitrogen rich compounds and amino acids. In summary, our investigation highlights that cysteine restriction, by depleting GSH and CoA, exerts a maximal impact on weight loss, metabolism, and stress signaling compared to other amino acid restrictions. These findings may pave the way for innovative strategies for addressing a range of metabolic diseases and the growing obesity crisis.

The role of fibrosis in endometriosis: a systematic review.

Fibrosis is an important pathological feature of endometriotic lesions of all subtypes. Fibrosis is present in and around endometriotic lesions, and a central role in its development is played by myofibroblasts, which are cells derived mainly after epithelial-to-mesenchymal transition (EMT) and fibroblast-to-myofibroblast transdifferentiation (FMT). Transforming growth factor-β (TGF-β) has a key role in this myofibroblastic differentiation. Myofibroblasts deposit extracellular matrix (ECM) and have contracting abilities, leading to a stiff micro-environment. These aspects are hypothesized to be involved in the origin of endometriosis-associated pain. Additionally, similarities between endometriosis-related fibrosis and other fibrotic diseases, such as systemic sclerosis or lung fibrosis, indicate that targeting fibrosis could be a potential therapeutic strategy for non-hormonal therapy for endometriosis. This review aims to summarize the current knowledge and to highlight the knowledge gaps about the role of fibrosis in endometriosis. A comprehensive literature overview about the role of fibrosis in endometriosis can improve the efficiency of fibrosis-oriented research in endometriosis. A systematic literature search was performed in three biomedical databases using search terms for 'endometriosis', 'fibrosis', 'myofibroblasts', 'collagen', and 'α-smooth muscle actin'. Original studies were included if they reported about fibrosis and endometriosis. Both preclinical in vitro and animal studies, as well as research concerning human subjects were included. Our search yielded 3441 results, of which 142 studies were included in this review. Most studies scored a high to moderate risk of bias according to the bias assessment tools. The studies were divided in three categories: human observational studies, experimental studies with human-derived material, and animal studies. The observational studies showed details about the histologic appearance of fibrosis in endometriosis and the co-occurrence of nerves and immune cells in lesions. The in vitro studies identified several pro-fibrotic pathways in relation to endometriosis. The animal studies mainly assessed the effect of potential therapeutic strategies to halt or regress fibrosis, for example targeting platelets or mast cells. This review shows the central role of fibrosis and its main cellular driver, the myofibroblast, in endometriosis. Platelets and TGF-β have a pivotal role in pro-fibrotic signaling. The presence of nerves and neuropeptides is closely associated with fibrosis in endometriotic lesions, and is likely a cause of endometriosis-associated pain. The process of fibrotic development after EMT and FMT shares characteristics with other fibrotic diseases, so exploring similarities in endometriosis with known processes in diseases like systemic sclerosis, idiopathic pulmonary fibrosis or liver cirrhosis is relevant and a promising direction to explore new treatment strategies. The close relationship with nerves appears rather unique for endometriosis-related fibrosis and is not observed in other fibrotic diseases. N/A.

Revisiting Pulmonary Sclerosing Pneumocytoma.

Pulmonary sclerosing pneumocytoma (PSP) is a quite rare tumor outside Eastern countries. This rarity, together with a wide histological appearance, makes its correct identification a diagnostic challenge for pathologists under the microscope. Historically, PSP was considered a vascular-derived neoplasm (sclerosing hemangioma), but its immunohistochemical profile clearly supports its epithelial origin. No specific molecular fingerprint has been detected so far. This short narrative revisits the clinical, histological, immunohistochemical, and molecular aspects of this tumor, paying special attention to some controversial points still not well clarified, i.e., clinical aggressiveness and metastatic spread, multifocality, the supposed development of sarcomatoid change in a subset of cases, and tumor associations with lung adenocarcinoma and/or well-differentiated neuroendocrine hyperplasia/tumors. The specific diagnostic difficulties on fine-needle aspiration cytology/biopsy and perioperative frozen sections are also highlighted. Finally, a teaching case of tumor concurrence of lung adenocarcinoma, neuroendocrine lesions, and PSP, paradigmatic of tumor association in this context, is also presented.

Extranodal marginal zone lymphoma of the larynx: A case report and scoping review.

This scoping review aims to review cases of extranodal marginal zone lymphoma (MZL) of the larynx to establish best management practices for this rare clinical entity. In this paper, we report a case of laryngeal MZL, in accordance with CARE guidelines. We then performed a scoping review according to PRISMA-ScR criteria of published cases of MZL involving the larynx. The following data were collected for each case: age, sex, size, location(s) involved, stage, treatment, follow-up, and recurrence duration. Sixty-six patients with laryngeal MZL, first reported in 1990, were identified. Characterized by its low-grade histological appearance and indolent course, laryngeal MZL is generally confined to the larynx and has an excellent prognosis with radiation used as first-line therapy. It is imperative for clinicians to consider lymphoma in the differential diagnosis of a laryngeal tumor from any subsite, as certain pathologies may carry high risks of metastasis.

Introduction and impact of routine whole genome sequencing in the diagnosis and management of sarcoma

BackgroundSarcomas are diverse neoplasms with highly variable histological appearances in which diagnosis is often challenging and management options for metastatic/unresectable disease limited. Many sarcomas have distinctive molecular alterations, but the range of alterations is large, variable in type and rapidly increasing, meaning that testing by limited panels is unable to capture the broad spectrum of clinically pertinent genomic drivers required. Paired whole genome sequencing (WGS) in contrast allows comprehensive assessment of small variants, copy number and structural variants along with mutational signature analysis and germline testing.MethodsIntroduction of WGS as a diagnostic standard for all eligible patients with known or suspected soft tissue sarcoma over a 2-year period at a soft tissue sarcoma treatment centre.ResultsWGS resulted in a refinement in the diagnosis in 37% of cases, identification of a target for personalised therapy in 33% of cases, and a germline alteration in 4% of cases.ConclusionIntroduction of WGS poses logistical and training challenges, but offers significant benefits to this group of patients.

P-105 Gender affirming hormone therapy affects the spermatogonial cell compartment in transwomen

Abstract Study question What are the specific changes under gender affirming hormone therapy (GAHT) in the spermatogonial cell compartment in testicular tissues of transwomen? Summary answer GAHT has a negative effect on the most undifferentiated PIWIL4+ spermatogonia potentially leading to reduced chances for fertility preservation in transwomen. What is known already Transwomen take GAHT to achieve transition between the gender assigned at birth and their gender identity. GAHT leads to a reduction of the most advanced germ cells and a reduction of MAGEA4 positive spermatogonia (pan spermatogonial marker). Single-cell RNA sequencing studies identified spermatogonial subpopulations based on the expression of the marker genes PIWIL4, FGFR3, NANOS3, GFRA1, KIT, UTF1. PIWIL4+ cells are considered the origin of germ cell differentiation (state 0). State 1 and 2 spermatogonia are characterized by expression of GFRA1 and KIT, respectively. Study design, size, duration On the day of gender affirming surgery (GAS) testicular tissues and blood samples were collected of 25 age matched trans women (mean 28.1 yr), who underwent comparable GAHT regimens (10 or 12.5 mg cyproterone acetate and estrogens) between 2013 and 2018. 8 adult cis men (mean 34.5 yr) with complete spermatogenesis served as controls. Age, start and type of GAHT were assessed using a questionnaire. This study was approved by the local ethics committee. Participants/materials, setting, methods We performed immunohistochemical stainings to evaluate the expression of spermatogonial markers (MAGEA4, UTF1, PIWIL4, FGFR3, NANOS3, GFRA1) in Bouin’s-fixed testicular tissue sections. For each marker the number of positive cells per round tubular cross-section was determined in 25 round tubules. The spermatogonial proliferation rate was evaluated using immunofluorescence co-stainings for GFRA1/MIKI67/MAGEA4 and KIT/MKI67/MAGEA4. We scored 400 MAGEA4+ cells per individual and determined the proportion of GFRA1+/KIT+. MKI67+ cells among the GFRA1+/KIT+ were evaluated. Main results and the role of chance The number of MAGEA4+ spermatogonia and the proportion of PIWIL4+ spermatogonia within the MAGEA4+ spermatogonia were reduced in transwomen compared to controls (p < 0.001). In contrast, the relative proportion of UTF1+, FGFR3+ and NANOS3+ spermatogonia was comparable. The number of spermatogonia per tubule correlated negatively with the age at start of GAHT (p < 0.01) and the age on the day of GAS (p < 0.001). The treatment duration correlated negatively with the proportion of PIWIL4+ (p < 0.01) and NANOS3+ spermatogonia (p < 0.05). The immunofluorescence stainings in transwomen revealed a similar ratio of proliferating KI67+ spermatogonia, both within the GFRA1+ and KIT+ cells, compared to controls. These results show the negative effects of the GAHT itself on the population of spermatogonia as well as the individual susceptibility depending on age-related factors. These results have the potential to better define the chances for fertility preservation under GAHT. Limitations, reasons for caution Transwomen are a very heterogeneous patient group varying in age, different GAHT, different treatment durations, intake of co-medications and possible pre-existing medical conditions. Hence, testicular size and histological appearance of transwomen’s testes are heterogeneous. Wider implications of the findings Transwomen, who wish to have own biological children, have to be counseled with regard to fertility preservation, best before initiation of GAHT, in order to avoid adverse effects on spermatogonia. Individual counselling has to take place with regard to fertility preservation. Trial registration number 2012-555-f-S

Collision Lesions in Head and Neck Area: A Retrospective Study of 97 Reported Cases

Background: Collision (hybrid) lesions consist of two or more distinct histologic types occurring separately but within the same area. This review focuses on discussing all related and available case reports of hybrid lesions in the head and neck area. Methods: The literature was searched using several databases, including Scopus, Web of Science, PubMed, and Google Scholar. Papers published from 1990 to 2022 with full text available were considered for inclusion in the study. For a more comprehensive understanding, all lesions were categorized into cutaneous, jaw, and salivary gland groups and lesions in miscellaneous tissues. Results: In general, 97 reported collision lesions developed in the head and neck region. Among them, 31 (32%) and 34 (35%) cases were cutaneous hybrid lesions and in the jaws, respectively. In addition, 27 (27.8%) and 5 (5.1%) cases were in salivary glands and miscellaneous tissues, respectively. Conclusion: While the presence of true hybrid tumors is well-established, some reported cases have prompted researchers to categorize them as biphasic differentiations. The rarity of these cases contributes to limited knowledge regarding their clinical behavior, prognosis, and optimal treatment. It is crucial to emphasize the characteristic and potentially perplexing histological appearances.

Biomarker responsiveness in Norwegian Sea mussels, Mytilus edulis, exposed at low temperatures to aqueous fractions of crude oil alone and combined with dispersant

Biological effects of aqueous fractions of a crude oil, alone or in combination with dispersant, were investigated in mussels, Mytilus edulis, exposed at three temperatures (5, 10 and 15 °C). Polycyclic aromatic hydrocarbons (PAHs) tissue concentrations were determined, together with genotoxicity, oxidative stress and general stress biomarkers and the Integrated Biological Response (IBR) index. The bioaccumulation of individual PAHs varied depending on the exposure temperature, with relevant bioaccumulation of phenantrene and fluoranthene at 5 °C and heavier (e.g. 5-rings) PAHs at 15 °C. The values and response profiles of each particular biomarker varied with exposure time, concentration of the oil aqueous fraction and dispersant addition, as well as with exposure temperature. Indeed, PAH bioaccumulation and biomarker responsiveness exhibited specific recognizable patterns in mussels exposed at low temperatures. Thus, genotoxicity was recorded early and transient at 5 °C and delayed but unremitting at 10–15 °C. Catalase activity presented a temperature-dependent response profile similar to the genotoxicity biomarker; however, glutathione-S-transferase responsiveness was more intricate. Lysosomal membrane stability in digestive cells decreased more markedly at 5 °C than at higher temperatures and the histological appearance of the digestive gland tissue was temperature-specific, which was interpreted as the combined effects of PAH toxicity and cold stress. It can be concluded that the profile and level of the biological effects are definitely different at low temperatures naturally occurring in the Arctic/Subarctic region (e.g. 5 °C) than at higher temperatures closer to the thermal optimum of this species (10–15 °C).

PATH-14. A CLINICAL CONUNDRUM - INFANTILE POSTERIOR FOSSA EPENDYMOMA WITH YAP1:MAML FUSION?

Abstract BACKGROUND Ependymomas of infancy (0-18months) have been reported to comprise distinct clinical, pathological and genetic entities. Young age is typically associated with posterior fossa group A (PF-A) tumours and therefore a poor prognosis. Treatment of these infants is challenging with limited therapeutic options that have significant long-term sequelae. METHOD We report a single case of a 4-month old baby girl who presented with obstructive hydrocephalus and a presumed posterior fossa mass. RESULTS Imaging demonstrated a large fairly well-defined solid lesion with multiple T1 high and corresponding T2 intermediate signal intensity foci scattered throughout the lesion and marked mass effect on the cerebellum and fourth ventricle. The lesion was inseparable from the pineal gland, habenula and tectum and only mild diffusion restriction. Whilst initially considered to be a posterior fossa tumour, the presence of a claw sign with the tectal plate, favoured a tectal origin. Histological appearances, together with immunohistochemistry findings (GFAP positive and EMA patchy perinuclear dot expression) were consistent with classic ependymoma. Grading was difficult as mitotic activity was relatively low, although focal areas of high ki67 proliferation index were noted suggesting at least focal grade 3 areas. Retained expression of tumour cells for H3K27me3 on immunohistochemistry suggested the likely posterior fossa group B (PF-B) ependymoma. Local SNP chromosome microarray found no acquired clonal abnormality; with no detection of gain chromosome 1q; loss/LOH 6q; Loss/LOH 9p21.3 [CDKN2A, CDKN2B], chromothripsis 11q [ZFTA::RELA], Loss/LOH 17p13 [TP53] or Loss/LOH 22q [NF2]. Additional NGS sequencing identified a YAP1::MAML2 fusion (confirmed with targeted RT-PCR followed by subsequent Sanger sequencing). CONCLUSION This case highlights the challenges with overlapping clinical, pathological and radiological features in an infant with ependymoma, necessitating a molecular diagnosis. After 21months, the patient remains in complete remission following surgery alone.

PATH-02. THE IMPACT OF EVOLVING DIAGNOSTIC METHODOLOGY ON THE CLASSIFICATION AND OUTCOME OF CENTRAL NERVOUS SYSTEM TUMOURS IN CHILDHOOD: A RETROSPECTIVE COHORT STUDY

Abstract BACKGROUND Central nervous system tumours are the second most common childhood tumours and the largest cause of childhood cancer death in Australia. Tumours arise from many cell types within the developing and mature CNS, leading to a wide spectrum of clinical behaviour despite overlapping histological appearances. Emerging molecular testing methods allow more precise determination of cell lineage as well as genetic and epigenetic changes driving tumour development. Particularly since 2016, molecular findings have been incorporated into international classification schema, potentially impacting the frequency of individual diagnoses and their observed prognosis. METHODS We performed a retrospective cohort study including patients with newly diagnosed CNS tumours at Royal Children’s Hospital, Melbourne between 2011 and 2020 (total 473). The first and last 100 eligible patients in the data set were reviewed for diagnosis, survival and recorded use of molecular testing. Reviewed patients were assigned to one of two cohorts, Cohort 1 2011-2013 (pre-2016 WHO revision) or Cohort 2 2018-2020 (post-2016 WHO revision). RESULTS The frequency of diagnoses on biopsy rather than imaging alone was stable (81% Cohort 1 vs 83% Cohort 2). Molecular testing utilization increased markedly over time (10 molecular investigations in Cohort 1 vs 348 in Cohort 2). The incidence of astrocytic and oligodendroglial diagnoses was stable. The incidence of embryonal and neuronal/ mixed glial neuronal diagnoses increased in Cohort 2, and the incidence of ependymal diagnoses decreased (p=0.0122). There were no event free or overall survival differences between the whole of Cohorts 1 and 2, with numbers of individual diagnoses too small for meaningful comparisons over time. CONCLUSIONS Access to molecular testing has impacted on the pattern of reported diagnoses of central nervous system tumours in children. Although outcomes have not changed, it is hoped that over time, improved molecular understanding will lead to more effective therapy selection.

Tumor microenvironment of Burkitt lymphoma: different immune signatures with different clinical behavior

AbstractBurkitt lymphoma (BL) is characterized by a tumor microenvironment (TME) in which macrophages represent the main component, determining a distinct histological appearance known as “starry sky” pattern. However, in some instances, BL may exhibit a granulomatous reaction that has been previously linked to favorable prognosis and spontaneous regression. The aim of our study was to deeply characterize the immune landscape of 7 cases of Epstein-Barr virus–positive (EBV+) BL with granulomatous reaction compared with 8 cases of EBV+ BL and 8 EBV-negative (EBV–) BL, both with typical starry sky pattern, by Gene expression profiling performed on the NanoString nCounter platform. Subsequently, the data were validated using multiplex and combined immunostaining. Based on unsupervised clustering of differentially expressed genes, BL samples formed 3 distinct clusters differentially enriched in BL with a diffuse granulomatous reaction (cluster 1), EBV+ BL with typical starry sky pattern (cluster 2), EBV– BL with typical “starry sky” (cluster 3). We observed variations in the immune response signature among BL with granulomatous reaction and BL with typical “starry sky,” both EBV+ and EBV–. The TME signature in BL with diffuse granulomatous reaction showed a proinflammatory response, whereas BLs with “starry sky” were characterized by upregulation of M2 polarization and protumor response. Moreover, the analysis of additional signatures revealed an upregulation of the dark zone signature and epigenetic signature in BL with a typical starry sky. Tumor-associated macrophages and epigenetic regulators may be promising targets for additional therapies for BL lymphoma, opening novel immunotherapeutic strategies.

Histopathological aspects of usual interstitial pneumonia in patients with systemic connective tissue diseases.

Five cases of patients with systemic connective tissue diseases (CTD) who developed connective tissue disease-associated interstitial lung disease (CTD-ILD) with progressive pulmonary fibrosis (PPF) are reported here. Unspecified ILD was diagnosed using high-resolution computed tomography (HRCT). Histologically, all cases were usual interstitial pneumonia (UIP) with findings of advanced (3/5) to diffuse (2/5) fibrosis, with a partially (4/5) to completely (1/5) formed image of a honeycomb lung. The fibrosis itself spread subpleurally and periseptally to more central parts (2/5) of the lung, around the alveolar ducts (2/5), or even without predisposition (1/5). Simultaneously, there was architectural reconstruction based on the mutual fusion of fibrosis without compression of the surrounding lung parenchyma (1/5), or with its compression (4/5). The whole process was accompanied by multifocal (1/5), dispersed (2/5), or organized inflammation in aggregates and lymphoid follicles (2/5). As a result of continuous fibroproduction and maturation of the connective tissue, the alveolar septa thickened, delimiting groups of alveoli that merged into air bullae. Few indistinctly visible (2/5), few clearly visible (1/5), multiple indistinctly visible (1/5), and multiple clearly visible (1/5) fibroblastic foci were present. Among the concomitant changes, areas of emphysema, bronchioloectasia, and bronchiectasis, as well as bronchial and vessel wall hypertrophy, and mucostasis in the alveoli and edema were observed. The differences in the histological appearance of usual interstitial pneumonia associated with systemic connective tissue diseases (CTD-UIP) versus the pattern associated with idiopathic pulmonary fibrosis (IPF-UIP) are discussed here. The main differences lie in spreading lung fibrosis, architectural lung remodeling, fibroblastic foci, and inflammatory infiltrates.

The influence of endurance exercise training on myocardial fibrosis and arrhythmogenesis in a coxsackievirus B3 myocarditis mouse model

Nonischaemic myocardial fibrosis is associated with cardiac dysfunction, malignant arrhythmias and sudden cardiac death. In the absence of a specific aetiology, its finding as late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging is often attributed to preceding viral myocarditis. Athletes presenting with ventricular arrhythmias often have nonischaemic LGE. Previous studies have demonstrated an adverse effect of exercise on the course of acute viral myocarditis. In this study, we have investigated, for the first time, the impact of endurance training on longer-term outcomes such as myocardial fibrosis and arrhythmogenicity in a murine coxsackievirus B3 (CVB)-induced myocarditis model. Male C57BL/6J mice (n = 72) were randomly assigned to 8 weeks of forced treadmill running (EEX) or no exercise (SED). Myocarditis was induced 2 weeks later by a single intraperitoneal injection with CVB, versus vehicle in the controls (PBS). In a separate study, mice (n = 30) were subjected to pretraining for 13 weeks (preEEX), without continuation of exercise during myocarditis. Overall, continuation of exercise resulted in a milder clinical course of viral disease, with less weight loss and better preserved running capacity. CVB-EEX and preEEX-CVB mice tended to have a lower mortality rate. At sacrifice (i.e. 6 weeks after inoculation), the majority of virus was cleared from the heart. Histological assessment demonstrated prominent myocardial inflammatory infiltration and cardiomyocyte loss in both CVB groups. Inflammatory lesions in the CVB-EEX group contained higher numbers of pro-inflammatory cells (iNOS-reactive macrophages and CD8+ T lymphocytes) compared to these in CVB-SED. Treadmill running during myocarditis increased interstitial fibrosis [82.4% (CVB-EEX) vs. 56.3% (CVB-SED); P = 0.049]. Additionally, perivascular and/or interstitial fibrosis with extensive distribution was more likely to occur with exercise [64.7% and 64.7% (CVB-EEX) vs. 50% and 31.3% (CVB-SED); P = 0.048]. There was a numerical, but not significant, increase in the number of scars per cross-section (1.9 vs. 1.2; P = 0.195), with similar scar distribution and histological appearance in CVB-EEX and CVB-SED. In vivo electrophysiology studies did not induce sustained monomorphic ventricular tachycardia, only nonsustained (usually polymorphic) runs. Their cumulative beat count and duration paralleled the increased fibrosis between CVB-EEX and CVB-SED, but the difference was not significant (P = 0.084 for each). Interestingly, in mice that were subjected to pretraining only without continuation of exercise during myocarditis, no differences between pretrained and sedentary mice were observed at sacrifice (i.e. 6 weeks after inoculation and training cessation) with regard to myocardial inflammation, fibrosis, and ventricular arrhythmogenicity. In conclusion, endurance exercise during viral myocarditis modulates the inflammatory process with more pro-inflammatory cells and enhances perivascular and interstitial fibrosis development. The impact on ventricular arrhythmogenesis requires further exploration.

Merkel cell carcinoma - particularities and morphological aspect of a unique and rare entity

Abstract Introduction: Merkel cell carcinoma is a very rare malignant neoplasm which presents high aggressivity, high recurrence rate and has meta-static potential. Our purpose is to present the histological and immunohistochemical particularities of Merkel Cell Carcinoma while reviewing potential differential diagnoses and challenges that we can encounter in daily practice. Case presentation: We present the case of an 86-year-old female patient who presented with a nodular tumour located in the left forearm, raising suspicion of a soft tissue tumour. The histological appearance of this unique type of cancer is highlighted on the Haematoxylin-eosin stain as a solid tumour composed of nests and chords of monomorphic cells. The nuclei of these tumoral cells appear characteristically as enlarged with dispersed chromatin. The immunohistochemical reactions have been performed and it was observed that the tumoral cells exhibited positivity for synaptophysin, CD56, NSE, EMA, as well as a “dot-like” expression for CK20. These histopathological and immunohistochemical features were consistent with a diagnosis of MCC, stage pT3, based on the assessment of tumour size. Conclusions: Sometimes, differentiating this tumour from other primary malignant neoplasms of the skin or even cutaneous metastases can be difficult. Immunohistochemistry remains the most important tool of diagnosis, especially for differentiating this neoplasm from metastatic neuroendocrine tumours that can affect the skin.

The effect of a barrier membrane on the incorporation of deproteinized bovine bone mineral (DBBM) in experimental defects at the time of early implant placement. A preclinical study

ObjectivesThis study aimed to assess membrane use with a bone substitute graft for guided bone regeneration (GBR) in experimental dehiscence defects.Materials and methodsMaxillary second incisors (I2) in 9 dogs were extracted. Six weeks later, implants were inserted and experimental dehiscence defects (5 × 3 mm) created on the buccal aspect. The defects and surrounding bone were grafted with deproteinized bovine bone mineral. One side (test) was covered with a resorbable collagen membrane whereas the contralateral side (control) was not. After 6 weeks, histomorphometrical analysis was performed to evaluate: (a) first bone-to-implant contact (fBIC), (b) buccal bone thickness at 1 mm increments from implant shoulder, (c) regenerated area (RA), (d) area and percentages of new bone (B), bone substitute (BS) and mineralized tissue (MT).ResultsThe histological appearance was similar between test and control sites. At central and lateral sections, there were no differences between groups for fBIC, buccal bone thickness, RA, BS, B, %B, MT and %MT. At central sections, membrane use favoured more %BS and %MT (p = 0.052). There was significantly more B, %B and MT at lateral compared to central sections.ConclusionsMembrane use tended to retain more bone substitute, but had no effect on new bone ingrowth. Lateral sections showed significantly more bone ingrowth and mineralized tissue compared to central sections, confirming that new bone ingrowth takes place mainly from the lateral walls of the defect.Clinical relevancePreclinical research to clarify the dynamics of bone regeneration in GBR procedures is relevant in clinical practice.

Efek Pemberian Mesenchymal Stem Cell Wharton's Jelly (MSC-WJ) terhadap Gambaran Histologi Pankreas Hewan Model Diabetes Melitus Tipe 1

Objective: This study was conducted to determine the effect of administering Mesenchymal Stem Cell Wharton Jelly (MSC-WJ) on the histological appearance of the pancreas of rat in a type 1 diabetes mellitus model. Methods: This research is an experimental research with a Posttest-Only Control Group Design. The sample consisted of 3 groups (Normal, T1DM, T1DM + MSC-WJ). The treatment group was treated with MSC-WJ for 4 weeks. Data analysis used One Way ANOVA and Post Hoc Bonferroni tests. Results: WJ-MSC can increase the mean diameter and area of the islets of Langerhans in the T1DM rat group from 98.08 mm – 126.85 mm and from 4911.95 mm2 – 8995.35 mm2, but this difference is not yet significant (p > 0.05). Conclusion This research shows that there is improvement in pancreatic damage by administering WJ-MSC to diabetic rat due to alloxan induction.

Metabolic pathway-based subtypes associate glycan biosynthesis and treatment response in head and neck cancer

Head and Neck Squamous Cell Carcinoma (HNSCC) is a heterogeneous malignancy that remains a significant challenge in clinical management due to frequent treatment failures and pronounced therapy resistance. While metabolic dysregulation appears to be a critical factor in this scenario, comprehensive analyses of the metabolic HNSCC landscape and its impact on clinical outcomes are lacking. This study utilized transcriptomic data from four independent clinical cohorts to investigate metabolic heterogeneity in HNSCC and define metabolic pathway-based subtypes (MPS). In HPV-negative HNSCCs, MPS1 and MPS2 were identified, while MPS3 was enriched in HPV-positive cases. MPS classification was associated with clinical outcome post adjuvant radio(chemo)therapy, with MPS1 consistently exhibiting the highest risk of therapeutic failure. MPS1 was uniquely characterized by upregulation of glycan (particularly chondroitin/dermatan sulfate) metabolism genes. Immunohistochemistry and pilot mass spectrometry imaging analyses confirmed this at metabolite level. The histological context and single-cell RNA sequencing data identified the malignant cells as key contributors. Globally, MPS1 was distinguished by a unique transcriptomic landscape associated with increased disease aggressiveness, featuring motifs related to epithelial-mesenchymal transition, immune signaling, cancer stemness, tumor microenvironment assembly, and oncogenic signaling. This translated into a distinct histological appearance marked by extensive extracellular matrix remodeling, abundant spindle-shaped cancer-associated fibroblasts, and intimately intertwined populations of malignant and stromal cells. Proof-of-concept data from orthotopic xenotransplants replicated the MPS phenotypes on the histological and transcriptome levels. In summary, this study introduces a metabolic pathway-based classification of HNSCC, pinpointing glycan metabolism-enriched MPS1 as the most challenging subgroup that necessitates alternative therapeutic strategies.

#3108 Rituximab in adult-onset IgA vasculitis

Abstract Background and Aims Adult-onset IgA Vasculitis (IgAV) is poorly responsive to glucocorticoids (GC) and conventional immunosuppressive therapies, such as cyclophosphamide. Rituximab has been successfully used in a few cases and may represent a safer and potentially more effective option [1]. Crescentic IgA Nephropathy (cIgAN), a rare entity that shares features of renal vasculitis with IgAV, is also frequently refractory to cyclophosphamide, while response to rituximab is unknown. We investigated outcomes after rituximab in a multicentre European cohort of adult-onset IgAV and cIgAN. Method We screened clinical records of patients followed at 18 European consorted centres who were ≥18 years old at the onset of IgAV and received ≥1 rituximab dose. Furthermore, we identified patients with cIgAN (≥25% crescentic glomeruli and rapidly progressive glomerulonephritis), who were treated with rituximab. Remission was defined as Birmingham Vasculitis Activity Score (BVAS) <3 at month 6 after rituximab and renal response as stable or improved eGFR and ≥50% proteinuria reduction. Relapse was defined as an increase in BVAS requiring a change in immunosuppressive therapy. Outcomes of IgAV with severe nephritis (eGFR <60 mL/min) were compared with those of cIgAN. Results We included 61 patients with IgAV and 15 with cIgAN (Table). Rituximab was administered as initial therapy in 23/61 (38%) patients with IgAV and 13/15 with cIgAN (87%), while the remainder had refractory or relapsing disease. Active skin involvement was present in 49 patients (80%) and nephritis in 55 patients (90%) with IgAV at the time of starting rituximab. This was given alone in 13/61 (21%) or combined with GC in 48 (79%) patients with IgAV and in all those with cIgAN. Furthermore, cyclophosphamide was used in 15% of patients with IgAV and 40% of those with cIgAN. Remission at 6 months was achieved by 52 (85%) patients with IgAV and 12/13 (92%) of those treated with rituximab alone. A renal response was observed among 49/55 (89%) of those with nephritis. Patients with IgAV and severe nephritis had similar eGFR to those with cIgAN at the time of starting rituximab, but the latter had lower rate of remission and a higher frequency of kidney failure. A relapse occurred in 15/52 patients (29%) who achieved remission a median of 13 months (10-15) after rituximab. Eight patients resumed rituximab and achieved again remission. Conclusion Rituximab alone or in combination with GC and immunosuppressants appeared to achieve a high rate of remission in this cohort of adult-onset IgAV. Renal response among those with severe nephritis was also good, while this was worse among patients with cIgAN, suggesting substantial differences among these conditions despite similar histological appearances.

O21 Raman spectroscopy for detection of squamous cell carcinoma in recessive dystrophic epidermolysis bullosa skin

Abstract Introduction and aims Recessive dystrophic epidermolysis bullosa (RDEB) is a genetic skin disorder caused by biallelic pathogenic variants in COL7A1, which encodes type VII collagen (C7). Lack of C7 leads to blistering, chronic wounds, scarring and early onset of life-shortening squamous cell carcinomas (SCCs). Currently, the suspicion of SCC is mostly determined by clinical observation of visible changes in chronic wounds, and often requires multiple biopsies for histological diagnosis. This project aims to improve clinical care by developing a new noninvasive means of detecting SCC. To achieve this, we used Raman spectroscopy, a nondestructive analytical technique to study the changes occurring in RDEB skin when SCC is present, with the goal of creating a bedside test that can aid clinicians in the early diagnosis of SCC. Methods Raman spectroscopic imaging was performed on 7-µm frozen skin sections from RDEB (n = 3), RDEB SCC (n = 3) and normal skin (n = 3) to identify signalling changes between nonlesional and lesional states. An in-depth molecular composition analysis of the samples was performed using multivariate analysis with the goal of highlighting changes in abundance of specific molecules when SCC is present. Results For both nonmalignant and RDEB SCC skin sites we found specific Raman peaks associated with protein (1004 cm−1, 1650 cm−1) or lipids (1450 cm−1). RDEB SCC indicated a relative increase in DNA and protein. High-quality Raman spectroscopic images could be acquired that showed clear correlation with histological appearances. Current work is under way to determine which specific biological compounds contribute to the Raman spectra observed. Conclusions Raman spectroscopic imaging can provide comprehensive and noninvasive molecular tissue mapping with resolution comparable to histological sections, enabling molecular-based detection of SCC. Future work will focus on characterization of the SCC molecular profile, in addition to determining whether fibre optic Raman spectroscopy can be used to guide the biopsy/resection of RDEB lesions.

Fumarate Hydratase-Deficient Renal Cell Carcinoma—A Clinicopathological Study of a Series of 11 Cases

Abstract Introduction Fumarate hydratase (FH)-deficient renal cell carcinoma (RCC) is a rare, molecularly defined renal tumor with aggressive behavior. The diagnosis of these tumors is challenging because of varied morphology and limited access to molecular testing and immunohistochemistry (IHC) for FH and 2-succinocysteine. We aim to elucidate the histomorphology, clinical presentation, and follow-up of this tumor in this first series of cases of FH-deficient RCCs from India. Objectives This article aims to understand and elucidate the clinical presentation, pathologic findings, treatment options, and outcomes of FH-deficient RCC. Materials and Methods Diagnosed cases of FH-deficient RCC between January 2021 and January 2023 including clinical details were retrieved from the electronic medical record database. Histopathological and immunohistochemical slides were reviewed. Results Out of 11 cases of FH-deficient RCC, 36% had been referred with a diagnosis of type 2 papillary RCC. One patient presented with metastatic disease. All had mixed histologic patterns with the predominant pattern being papillary and showed FH loss on IHC. The classically described inclusion like nucleoli was present only focally in most cases. A subset of tumors had low-grade solid-nested morphology and these patients presented at an earlier stage (T2a). Two patients on multikinase inhibitors are alive with disease at 14 months' follow-up. Conclusion FH-deficient RCCs can have varied histologic patterns within the same tumor and show loss of FH expression by IHC. A subset has low grade morphology and tends to have a more indolent course. It is important to have a high index of suspicion for this diagnosis due to its varied histological appearance and aggressive behavior.