Search

Eosinophilic esophagitis (EoE) is an allergic inflammatory condition of the esophagus associated with elevated numbers of eosinophils. Disease diagnosis and monitoring require determining the concentration of eosinophils in esophageal biopsies, a time-consuming, tedious and somewhat subjective task currently performed by pathologists. Here, we developed a machine learning pipeline to identify, quantitate and diagnose EoE patients' at the whole slide image level. We propose a platform that combines multi-label segmentation deep network decision support system with dynamics convolution that is able to process whole biopsy slide. Our network is able to segment both intact and not-intact eosinophils with a mean intersection over union (mIoU) of 0.93. This segmentation enables the local quantification of intact eosinophils with a mean absolute error of 0.611 eosinophils. We examined a cohort of 1066 whole slide images from 400 patients derived from multiple institutions. Using this set, our model achieved a global accuracy of 94.75%, sensitivity of 94.13%, and specificity of 95.25% in reporting EoE disease activity. Our work provides state-of-the-art performances on the largest EoE cohort to date, and successfully addresses two of the main challenges in EoE diagnostics and digital pathology, the need to detect several types of small features simultaneously, and the ability to analyze whole slides efficiently. Our results pave the way for an automated diagnosis of EoE and can be utilized for other conditions with similar challenges.

BACKGROUND AND AIMS: Colonic eosinophilia, an enigmatic finding often referred to as eosinophilic colitis (EoC), is a poorly understood condition. Whether EoC is a distinct disease or a colonic manifestation of eosinophilic gastrointestinal diseases (EGIDs) or inflammatory bowel disease (IBD) is undetermined. METHODS: Subjects with EoC (n=27) and controls (normal [NL, n=20], Crohn disease [CD, n=14]) were enrolled across sites associated with the Consortium of Eosinophilic Gastrointestinal Disease Researchers (CEGIR). EoC was diagnosed as colonic eosinophilia (ascending ≥100, descending ≥85, sigmoid ≥65 eosinophils/high-power field) with related symptoms. Colon biopsies were subjected to RNA sequencing. Associations between gene expression and histologic features were analyzed with Spearman correlation; operational pathways and cellular constituents were computationally derived. RESULTS: We identified 987 differentially expressed genes (EoC transcriptome) between EoC and NL (>1.5-fold change, P < .05). Colonic eosinophil count correlated with 31% of EoC transcriptome, most notably with CCL11 and CLC (r=0.78 and 0.77, P < .001). Among EoC and other EGIDs, there was minimal transcriptomic overlap; and minimal evidence of a strong allergic type 2 immune response compared with other EGIDs. Decreased cell-cycle and increased apoptosis in EoC compared with NL were identified by functional enrichment analysis and immunostaining using Ki-67 and cleaved caspase-3. Pericryptal circumferential eosinophil collars were associated with the EoC transcriptome (P < .001). EoC transcriptome-based scores were reversible with disease remission and differentiated EoC from IBD, even after controlling for colonic eosinophil levels (P < .0001). CONCLUSION: We established EoC transcriptomic profiles, identified mechanistic pathways, and integrated findings with parallel IBD and EGID data. These findings establish EoC as a distinct disease compared with other EGIDs and IBD, thereby providing a basis for improving diagnosis and treatment.

Eosinophilic esophagitis (EoE) can progress to fibrostenosis by unclear mechanisms. Herein, we investigated gene dysregulation in fibrostenotic EoE, its association with clinical parameters and specific pathways, and the functional consequences.Esophageal biopsies from subjects with EoE were collected across 11 Consortium of Eosinophilic Gastrointestinal Disease Researchers sites (n = 311) and 2 independent replication cohorts (n = 83). Inclusion criteria for fibrostenotic EoE were endoscopic rings, stricture, and/or a history of dilation. Endoscopic, histologic, and molecular features were assessed by the EoE Endoscopic Reference Score, EoE Histology Scoring System, EoE Diagnostic Panel, and RNA sequencing. Esophageal endothelial TSPAN12 expression and functional effects on barrier integrity and gene expression were analyzed in vitro.TSPAN12 was the gene most correlated with fibrostenosis (r = -0.40, P.001). TSPAN12 was lower in fibrostenotic EoE and correlated with EoE Endoscopic Reference Score, EoE Diagnostic Panel, and EoE Histology Scoring System (r = 0.34-0.47, P.001). Lower TSPAN12 associated with smaller esophageal diameter (r = 0.44, P = .03), increased lamina propria fibrosis (r = -0.41, P.001), and genes enriched in cell cycle-related pathways. Interleukin (IL)-13 reduced TSPAN12 expression in endothelial cells. Conversely, anti-IL-13 therapy increased TSPAN12 expression. TSPAN12 gene silencing increased endothelial cell permeability and dysregulated genes associated with extracellular matrix pathways. Endothelial cell-fibroblast crosstalk induced extracellular matrix changes relevant to esophageal remodeling.Patients with fibrostenotic EoE express decreased levels of endothelial TSPAN12. We propose that IL-13 decreases TSPAN12, likely contributing to the chronicity of EoE by promoting tissue remodeling through fibroblast-endothelial cell crosstalk.

The aim of the study was to determine the mucosal microbiota associated with eosinophilic esophagitis and eosinophilic gastritis in a geographically diverse cohort of patients compared to controls.We conducted a prospective study of individuals with eosinophilic gastrointestinal disease in the Consortium of Eosinophilic Gastrointestinal Disease Researchers (CEGIR), including pediatric and adult tertiary care centers. Eligible individuals had clinical data, mucosal biopsies and stool collected. Total bacterial load was determined from mucosal biopsy samples by quantitative PCR. Community composition was determined by small subunit rRNA gene amplicons.139 mucosal biopsies were evaluated corresponding to 93 EoE, 17 EoG and 29 control specimens (18 esophageal) from 10 sites across the United States. Dominant community members across disease activity differed significantly. When comparing EoE and EoG with controls, the dominant taxa in individuals with EGIDs was increased (Streptococcus in esophagus; Prevotella in stomach). Specific taxa were associated with active disease for both EoE (Streptococcus, Gemella) and EoG (Leptotrichia), although highly individualized communities likely impacted statistical testing. Alpha diversity metrics were similar across groups, but with high variability amongst individuals. Stool analyses did not correlate with bacterial communities found in mucosal biopsy samples and was similar in patients and controls.Dominant community members (Streptococcus for EoE, Prevotella for EoG) were different in the mucosal biopsies but not stool of individuals with EGIDs compared to controls; taxa associated with EGIDs were highly variable across individuals. Further study is needed to determine if therapeutic interventions contribute to the observed community differences.

The Core Outcome Set for Therapeutic Studies in Eosinophilic Esophagitis (COREOS) collaborators are a group of more than 70 gastroenterologists, pathologists, allergists, researchers, dietitians, psychologists, and methodologists who convened in a series of in-person and virtual meetings between 2018 and 2020 with the aim of developing a core outcome set (COS) for use in therapeutic studies of pharmacologic and dietary therapies for the treatment of eosinophilic esophagitis (EoE). Given heterogeneity in reported outcomes and uncertainties regarding the most appropriate end points for use in both randomized controlled trials (RCTs) and observational studies involving EoE patients, the EoE experts launched the COREOS exercise in 2018 to standardize outcome definitions using methods established by the Core Outcome Measures in Effectiveness Trials (COMET) initiative.1,2 The COS was developed using a multiphase approach, which is summarized in Figure 1. In the first phase, systematic reviews of the literature and patient engagement surveys were conducted to identify candidate outcomes that have been previously measured and are important to patients with EoE. Next, this information was used to build a framework of different outcome domains, and working groups for each domain were assembled to review the literature for relevant end points.3–6 The relative importance of these domains was categorized in a Delphi survey as core, important, and research agenda domains, and discussed in a moderated in-person meeting on May 17, 2019 at Digestive Disease Week (San Diego, CA). In phase 3, a comprehensive list of outcome measures within each of the core domains was evaluated by the COREOS collaborators in a 2-round Delphi survey and, finally, outcomes were ratified in a virtual meeting on December 8, 2020. In this meeting summary, we highlight the major points of discussion that occurred during the development of the EoE COS.

Chronic graft failure (CGF) is the leading cause of mortality in pediatric heart transplant (PHT) patients and has multifactorial pathogenesis including cardiac allograft vasculopathy (CAV). CGF can present with microvessel disease (MVD) and myocardial fibrosis on endomyocardial biopsies (EMB). We investigated if CGF due to moderate- severe (M-S) CAV has histopathologic MVD and fibrosis prior to or at the time of CAV diagnosis.This retrospective case-control study included PHT with CGF secondary to M-S CAV. Control patients had no CAV or CGF. EMBs from CAV (3 sets: at one-year post-transplant 1yrCAV, pre-CAV, and at the time of CAV diagnosis) and non-CAV cohorts were reviewed to grade the fibrosis and quantify MVD. Histopathologic changes were correlated and compared between CAV/non-CAV groups.Each group had 8 patients. The median age at transplantation and time since transplant were similar between the two groups (p=0.71 and p=0.91, respectively). Fibrosis grade was 3.0 for CAV cohort compared to 1.0 for control (p= 0.003) and MVD score was 2.1 in CAV and 0.5 in non-CAV patients (p= 0.003). Similar degrees of fibrosis and MVD were present even before any evidence of CAV (1yrCAV fibrosis grade 2.5, pre-CAV fibrosis grade 2; 1yrCAV vs CAV p=0.75, pre-CAV vs CAV p=0.63; 1yrCAV MVD score 2, pre-CAV MVD score 2; 1yrCAV vs CAV p=1, pre-CAV vs CAV p=0.91). The degree of MVD correlated with fibrosis (r=0.63, p0.0001) for all EMBs.Simultaneous myocardial fibrosis and MVD are noted in CGF secondary to M-S CAV, changes that occur before angiographic CAV. EMBs can reveal significant changes in patients with subsequent development of CAV and may be used to modify the follow-up and treatment for these high-risk patients.

Patients with biallelic mutations in the nuclear-encoded mitochondrial gene C1QBP/p32 have been described with syndromic features and autosomal recessive cardiomyopathy. We describe the clinical course in two siblings who developed cardiomyopathy and ventricular fibrillation in infancy. We provide genomic analysis and clinical-pathologic correlation. Both siblings had profound cardiac failure with ventricular arrhythmia. One child died suddenly. The second sibling survived resuscitation but required extracorporeal cardiopulmonary support and died shortly afterward. On cardiac autopsy, the left ventricle was hypertrophied in both children. Histological examination revealed prominent cardiomyocyte cytoplasmic clearing, and electron microscopy confirmed abnormal mitochondrial structure within cardiomyocytes. DNA sequencing revealed compound heterozygous variants in C1QBP (p.Thr40Asnfs*45 and p.Phe204Leu) in both children. Family segregation analysis demonstrated each variant was inherited from an unaffected, heterozygous parent. Inherited loss of C1QBP/p32 is associated with recessive cardiomyopathy, ventricular fibrillation, and sudden death in early life. Ultrastructural mitochondrial evaluation in the second child was similar to findings in engineered C1qbp-deficient mice. Rapid trio analysis can define rare biallelic variants in genes that may be implicated in sudden death and facilitate medical management and family planning. (184/200).

Pediatric bone marrow assessment by MRI is challenging and primarily experiential and qualitative, with a paucity of clinically useful quantitative imaging techniques. MRI fat fraction (MRI-FF) is a technique used to quantify the degree of fat in other organ systems. The purpose of this study was to assess whether MRI-FF accurately measures bone marrow composition. This two-part study included a validation phase, followed by an application phase. For the validation phase, the MRI-FF of piglet bones (6 long bones, 8 axial bones) was performed at 1.5 tesla (T) and 3.0 T, and correlated to the histological fat fraction (H-FF). We used Bland–Altman plots to compare MRI-FF at 1.5 tesla T and 3.0 T. For the application phase, five children with malignant marrow disease were recruited along with seven age- and gender-matched control subjects. The MRI-FF in the children was correlated to the H-FF. Boxplots were used to compare the MRI-FF of patients and control subjects. For the validation animal study, the MRI-FF of piglet bones at both 1.5 T and 3.0 T demonstrated moderate positive correlation to H-FF (r=0.41 and 0.42, respectively). MRI-FF at 1.5 T and 3.0 T were in good agreement, on average 7.7% apart. For the application phase, we included 5 children (4 with leukemia, 1 rhabdomyosarcoma) with median age 7 years, range (3–10 years). All children had MRI-FF and H-FF below 10%. The MRI-FF in patients (3.8±1.2) was significantly lower than that of control subjects (46.1±12.3%) (P

Background Pathologic examination of conduction system (CS) is not routinely performed, and histologic changes are mostly reported in forensic practice. Methods We studied the value of dissecting the CS in a cohort of pediatric patients with unexplained sudden death or severe, inexplicable arrhythmias. Histopathologic changes present in CS components were recorded and correlated with findings noted in other cardiac structures. Results Twenty-one subjects (11 unexplained sudden deaths and 10 life-threatening arrhythmias) were identified; 18 (86%) had CS pathologic abnormalities. In 13 patients (62%), the CS findings mirrored those found in other cardiac sections (inflammation, allograft vasculopathy, vascular fibromuscular dysplasia, cardiomyopathy-related changes, and tumor/tumor-like conditions). Five cases (24%) had abnormalities restricted to CS (bundle of His [BH] with fibrotic scar and patch material following ventricular septal defect repair, inflammation, BH with fibrosis and calcifications, and intimal fibroplasia of sinoatrial node artery). Conclusions Pathologic changes within the CS are present in a high number of pediatric patients presenting with unexplained sudden death or life-threatening arrhythmias. Frequently, the findings mirror those observed in other cardiac structures. However, in a significant number of cases (24%), the changes are restricted to CS and likely explain the patients’ symptoms or cause of death, suggesting that systematic dissection of CS unveils valuable information.

OBJECTIVES: Mast cells (MCs) are increased in eosinophilic esophagitis (EoE). Endoscopic abnormalities, symptoms, and epithelial changes can persist after treatment despite a reduction of esophageal eosinophilia. It is unknown whether this could be due to persistent MC infiltration. We aimed to determine whether patients with histologically inactive (HI) EoE (defined as

BACKGROUND: Eosinophilic gastritis (EG) is a clinicopathologic disorder with marked gastric eosinophilia and clinical symptoms. There is an unmet need in EG for more precise diagnostic tools. OBJECTIVE: We aimed to develop tissue- and blood-based diagnostic platforms for EG. METHODS: Patients with EG and non-EG controls were enrolled across 9 Consortium of Eosinophilic Gastrointestinal Disease Researchers (CEGIR)-associated sites. An EG Diagnostic Panel (EGDP; gastric transcript subset) and EG blood biomarker panel (protein multiplex array) were analyzed. The EGDP(18) scores were derived from the expression of 18 highly dysregulated genes and Blood EG scores from dysregulated cytokines/chemokine levels. RESULTS: Gastric biopsies and blood samples from 185 subjects (EG 74, non-EG 111) were analyzed. The EGDP a) identified patients with active EG (P < .0001, AUC ≥0.95); b) effectively monitored disease activity in longitudinal samples (P = .0078); c) highly correlated in same-patient samples (antrum vs. body, r = 0.85, P < .0001); and d) inversely correlated with gastric peak eosinophil levels (r = −0.83, P < .0001), periglandular circumferential collars (r = − 0.73, P < .0001), and endoscopic nodularity (r = −0.45, P < .0001). For blood-based platforms, eotaxin-3, TARC, IL-5, and TSLP levels were significantly increased. Blood EG scores a) distinguished patients with EG from non-EG controls (P < .0001, AUC ≥0.91); b) correlated with gastric eosinophil levels (plasma r = 0.72, P = .0002; serum r = 0.54, P = .0015); and c) inversely correlated with EGDP(18) scores (plasma r = −0.64, P = .0015; serum r = −0.46, P = .0084). Plasma eotaxin-3 strongly associated with gastric CCL26 expression (r = 0.81, P < .0001). CONCLUSION: We developed tissue- and blood-based platforms for assessment of EG and uncovered robust associations between specific gastric molecular profiles and histologic and endoscopic features, providing insight and tools for this emerging rare disease.

Pigmented epithelioid melanocytoma (PEM) is considered an intermediate grade melanocytic lesion that is histologically indistinguishable from epithelioid blue nevi associated with Carney complex. PEM are characterized by an intradermal population of heavily pigmented epithelioid-shaped melanocytes along with some spindled and dendritic melanocytes with frequent melanophages. These melanocytic tumors occasionally involve regional lymph nodes but only rarely result in distant metastases. Recent studies have demonstrated a variable but limited number of specific genomic aberrations including protein kinase A regulatory subunit alpha (PRKAR1A), BRAF, GNAQ, and MAP2K1 mutations as well as protein kinase C alpha isoform (PRKCA) fusions. We performed an 8-year retrospective review of our database and identified 16 cases of PEM. Using targeted DNA sequencing and RNA-seq to assess 1714 cancer-related genes, we detected gene fusions involving PRKCA in 31% of cases (5/16) with 5' partners SCARB1(12q24) in 2 cases, CD63 (12q13) in 1 case, ATP2B4 (1q32) in 1 case, and MAP3K3 (17q23) in 1 case. Additional fusions were identified in TPR-NTRK1 (1/16), ALK (1/16), and MYO5A-NTRK3 (1/16). PRKCA fusion lesions tended to occur in younger-aged patients and histologic examination demonstrated sheets of monomorphic epithelioid-shaped melanocytes, moderate to high-grade nuclear atypia, and higher mitotic activity (P=0.037). Our gene panel also identified previously described mutations in PRKAR1A, GNAQ, MAP2K1, BRAF, NF1. To our knowledge, this is the largest and most comprehensive study of PEM integrating molecular data with histologic features that can be utilized in future studies for improved subclassification and prognostication of heavily pigmented melanocytic neoplasms.

Although the prenatal hippocampus displays deficits in cellular proliferation/migration and volume, which are later associated with memory deficits, little is known about the effects of trisomy 21 on postnatal hippocampal cellular development in Down syndrome (DS). We examined postnatal hippocampal neuronal profiles from autopsies of DS and neurotypical (NTD) neonates born at 38-weeks’-gestation up to children 3 years of age using antibodies against non-phosphorylated (SMI-32) and phosphorylated (SMI-34) neurofilament, calbindin D-28k (Calb), calretinin (Calr), parvalbumin (Parv), doublecortin (DCX) and Ki-67, as well as amyloid precursor protein (APP), amyloid beta (Aβ) and phosphorylated tau (p-tau). Although the distribution of SMI-32-immunoreactive (-ir) hippocampal neurons was similar at all ages in both groups, pyramidal cell apical and basal dendrites were intensely stained in NTD cases. A greater reduction in the number of DCX-ir cells was observed in the hippocampal granule cell layer in DS. Although the distribution of Calb-ir neurons was similar between the youngest and oldest NTD and DS cases, Parv-ir was not detected. Conversely, Calr-ir cells and fibers were observed at all ages in DS, while NTD cases displayed mainly Calr-ir fibers. Hippocampal APP/Aβ-ir diffuse-like plaques were seen in DS and NTD. By contrast, no Aβ1–42 or p-tau profiles were observed. These findings suggest that deficits in hippocampal neurogenesis and pyramidal cell maturation and increased Calr immunoreactivity during early postnatal life contribute to cognitive impairment in DS.

DICER1 tumor predisposition syndrome is a rare genetic disorder that predisposes individuals to multiple benign and malignant neoplasms. The phenotype is vast and includes pleuropulmonary blastoma (PPB), thyroid nodules, cystic nephroma, Wilms tumor, ovarian Sertoli–Leydig cell tumor, and medulloepithelioma, among others. Herein, we describe a patient with a DICER1 germline pathogenic variant presenting with two neoplasms that are not commonly encountered in the context of DICER1 syndrome. The first tumor is a multiloculated cystic hepatic lesion with a biphasic pattern, composed of cysts lined by bland biliary type (CK19-positive) epithelium surrounded by a condensation of sarcomatous spindled cell proliferation in a myxoid stroma. This neoplasm resembled PPB or cystic nephroma with malignant transformation. The second tumor is a chest nodule consistent with low-grade hidradenocarcinoma. Although it is difficult to speculate with just a single case, these unusual neoplasms occurring in particular at a young age raises the possibility that they can be inherent to, and thus, be part of the DICER1 tumor predisposition syndrome phenotype.

BACKGROUND: End points used to determine treatment efficacy in eosinophilic esophagitis (EoE) have evolved over time. With multiple novel therapies in development for EoE, harmonization of outcomes measures will facilitate evidence synthesis and appraisal when comparing different treatments. OBJECTIVE: We sought to develop a core outcome set (COS) for controlled and observational studies of pharmacologic and diet interventions in adult and pediatric patients with EoE. METHODS: Candidate outcomes were generated from systematic literature reviews and patient engagement interviews and surveys. Consensus was established using an iterative Delphi process, with items voted on using a 9-point Likert scale and with feedback from other participants to allow score refinement. Consensus meetings were held to ratify the outcome domains of importance and the core outcome measures. Stakeholders were recruited internationally and included adult and pediatric gastroenterologists, allergists, dieticians, pathologists, psychologists, researchers, and methodologists. RESULTS: The COS consists of 4 outcome domains for controlled and observational studies: histopathology, endoscopy, patient-reported symptoms, and EoE-specific quality of life. A total of 69 stakeholders (response rate 95.8%) prioritized 42 outcomes in a 2-round Delphi process, and the final ratification meeting generated consensus on 33 outcome measures. These included measurement of the peak eosinophil count, Eosinophilic Esophagitis Histology Scoring System, Eosinophilic Esophagitis Endoscopic Reference Score, and patient-reported measures of dysphagia and quality of life. CONCLUSIONS: This interdisciplinary collaboration involving global stakeholders has produced a COS that can be applied to adult and pediatric studies of pharmacologic and diet therapies for EoE and will facilitate meaningful treatment comparisons and improve the quality of data synthesis. ispartof: JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY vol:149 issue:2 pages:659-670 ispartof: location:United States status: published

Pediatric bone marrow assessment by MRI is challenging and primarily experiential and qualitative, with a paucity of clinically useful quantitative imaging techniques.MRI fat fraction (MRI-FF) is a technique used to quantify the degree of fat in other organ systems. The purpose of this study was to assess whether MRI-FF accurately measures bone marrow composition.This two-part study included a validation phase, followed by an application phase. For the validation phase, the MRI-FF of piglet bones (6 long bones, 8 axial bones) was performed at 1.5 tesla (T) and 3.0 T, and correlated to the histological fat fraction (H-FF). We used Bland-Altman plots to compare MRI-FF at 1.5 tesla T and 3.0 T. For the application phase, five children with malignant marrow disease were recruited along with seven age- and gender-matched control subjects. The MRI-FF in the children was correlated to the H-FF. Boxplots were used to compare the MRI-FF of patients and control subjects.For the validation animal study, the MRI-FF of piglet bones at both 1.5 T and 3.0 T demonstrated moderate positive correlation to H-FF (r=0.41 and 0.42, respectively). MRI-FF at 1.5 T and 3.0 T were in good agreement, on average 7.7% apart. For the application phase, we included 5 children (4 with leukemia, 1 rhabdomyosarcoma) with median age 7 years, range (3-10 years). All children had MRI-FF and H-FF below 10%. The MRI-FF in patients (3.8±1.2) was significantly lower than that of control subjects (46.1±12.3%) (P0.01).MRI-FF is a valid technique to assess bone marrow fat fraction at both 1.5 T and 3.0 T. The MRI-FF in children with malignant marrow processes is significantly lower than in control subjects with normal marrow.

Esophageal dilation improves dysphagia but not inflammation in eosinophilic esophagitis (EoE) patients. We investigated if dilation modifies the association between symptoms and peak esophageal eosinophils per high-power field (eos/hpf).Adults enrolled in a multisite prospective Consortium of Gastrointestinal Eosinophilic Disease Researchers Outcome Measures for Eosinophilic Gastrointestinal Diseases Across Ages observational study (NCT02523118) completed the symptom-based EoE activity index (EEsAI) patient-reported outcome instrument and underwent endoscopy with biopsy specimens. Patients were stratified based on dilation status as absent, performed 1 year or less before endoscopy, and performed more than 1 year before endoscopy. Assessments included Spearman correlations of the relationship between symptoms and eos/hpf and linear regression with EEsAI as the outcome, eos/hpf as predictor, and interaction for dilation and eos/hpf.Among 100 patients (n = 61 males; median age, 37 y), 15 and 40 patients underwent dilation 1 year or less and more than 1 year before index endoscopy, respectively. In nondilated patients, the association between eos/hpf and symptoms was moderate (ρ = 0.49; P.001); for a 10-eos/hpf increase, the predicted EEsAI increased by 2.69 (P = .002). In patients dilated 1 or less and more than 1 year before index endoscopy, this association was abolished (ρ = -0.38; P = .157 for ≤1 y and ρ = 0.02; P = .8831 y); for a 10-eos/hpf increase, the predicted EEsAI changed by -1.64 (P = .183) and 0.78 (P = .494), respectively. Dilation modified the association between symptoms and eos/hpf (P = .005 and P = .187 for interaction terms of eos/hpf and dilation 1 or less years before and more than 1 year before index endoscopy, respectively).In nondilated EoE adults, eos/hpf correlate modestly with symptoms; this correlation was no longer appreciated in dilated patients, and the dilation effects lasted longer than 1 year. Dilation status should be considered in studies evaluating EoE treatment and for clinical follow-up evaluation.

Malignant ectomesenchymoma is a rare pediatric neoplasm with dual mesenchymal and neuroectodermal elements. Mesenchymal component is usually rhabdomyosarcoma, particularly embryonal subtype, whereas neuroectodermal derivatives are frequently a neuroblastic tumor. Ectomesenchymoma manifests in various sites given the wide migration of neural crest cells during development, though the pelvis/perineum is most often involved. Moreover, no unique unifying molecular abnormality has been determined.We conducted a retrospective study to analyze the spectrum of ectomesenchymal tumors encountered in our pediatric population. Six patients were identified and data pertaining to patients' demographic, tumor size and site, histologic components with immunophenotypic profile, molecular alterations, treatment, and outcome were collected.Mesenchymal elements, represented by rhabdomyosarcoma in all instances, were the dominant component in the majority of cases (5/6). Embryonal and alveolar morphology had similar distribution (3/6) and all patients with alveolar subtype harbored the characteristic translocations of this entity. The neuroectodermal component was most often a neuroblastic-like neoplasm (4/6); however, 2/6 cases demonstrated primitive neuroectodermal tumor-like morphology. No unifying alterations were found on molecular studies.Our analysis extends the histologic and molecular spectrum of these tumors and highlights their heterogeneity. The percentage of cases with alveolar rhabdomyosarcoma or primitive neuroectodermal-like tumor components suggests that these types of elements might be underreported. This study is also the first to demonstrate FOXO1 gene rearrangements in malignant ectomesenchymoma with alveolar rhabdomyosarcoma subtype.

Thrombotic complications are a significant source of morbidity and mortality following hematopoietic stem cell transplants. Among them, transplant-associated thrombotic microangiopathy (TA-TMA) is a well-recognized syndrome that can affect various organ systems. Its etiology is related to endothelial injury accompanied by complement activation. As many of the signs and symptoms of the disease are also encountered in other complications following hematopoietic stem cell transplant, it can often be difficult to establish the diagnosis based on clinical data alone. Histopathologic examination of various tissues may be performed in difficult cases. However, the microscopic features of TA-TMA also overlap with those seen in other posttransplant complications, suggesting a need for additional tests to help in diagnosis. Here we describe a patient who presented with hemolytic anemia, thrombocytopenia, renal and neurological impairment, who also developed significant bloody diarrhea. Flexible sigmoidoscopy with biopsies was performed to determine the exact etiology of his gastrointestinal bleed. A diagnosis of intestinal TA-TMA was established with the use of immunohistochemical stains for complement components C5b-9 and C4d. This is the first report that highlights the utility of complement staining on histologic sections from digestive samples to render a definitive diagnosis of intestinal TA-TMA.

Objectives Barrett esophagus (BE) and intestinal metaplasia of gastroesophageal junction (IMGEJ) are rare in the pediatric population. This multi-institutional retrospective study evaluated the clinicopathologic characteristics and natural history of BE and IMGEJ in children. Methods Data from 20 BE patients (70% boys, mean age: 14.9 years) and 17 IMGEJ patients (71% boys, mean age: 14 years) were retrospectively obtained from chart review. Endoscopic and pathologic findings from index and follow-up endoscopies were analyzed. Results Most patients (70% BE and 59% IMGEJ) had underlying conditions which put them at risk for gastroesophageal reflux disease. Increased body mass index (BMI) was observed in patients without underlying conditions (BE: 30.1 ± 9.8; IMGEJ: 23.9 ± 6.3) compared with those with underlying conditions (BE: 19.6 ± 7.8; IMGEJ: 16.4 ± 2.1) (BE, P = 0.02; IMGEJ, P = 0.01). Incomplete intestinal metaplasia (IM) was the predominant histology seen in BE (80%) and IMGEJ patients (75%). Dysplasia and malignancy were not identified in the initial and follow-up biopsies. Concurrent gastric biopsies showed various findings (79% BE and 40% IMGEJ were normal), with 1 IMGEJ patient showing coexisting gastric IM (7%). Follow-up in 12 BE patients (mean follow-up time 51.6 months) showed 100% persistent endoscopic disease and 58% persistent IM histologically. Three of 6 IMGEJ patients (mean follow-up time 24 months) demonstrated endoscopic and histologic features consistent with BE on subsequent procedures. Moreover, a subset of BE (57%) and IMGEJ patients (67%) who underwent endoscopy before initial diagnosis showed nongoblet columnar mucosa above the anatomic gastroesophageal junction. Conclusions Increased BMI may be a risk factor for BE and IMGEJ in pediatric patients without underlying conditions. Nongoblet columnar metaplasia and IMGEJ might represent incomplete forms of BE. Our data suggest that these patients should be closely monitored.

Context.— The Accreditation Council for Graduate Medical Education (ACGME) established a new system for accreditation of residency and fellowship programs in 2013. One key aspect of the Next Accreditation System is the 10-year self-study, which requires programs to conduct a comprehensive self-evaluation, including development of program aims and analysis of strengths, weaknesses, and environmental context, in order to plan improvements and take the program to the next level. Objective.— To provide a review of the recent changes and current state of ACGME accreditation, with a focus on the new 10-year self-study, and to share our institution's experience with conducting the first self-study of our pathology residency and accredited fellowship programs in 2018. Data Sources.— Review of English-language literature, published resources from the ACGME, and materials/data from our department's 2018 self-study. Conclusions.— The self-study process now required for ACGME accreditation is a useful way to assess program strengths and weaknesses in the context of current environmental and institutional factors, and helps develop an effective framework for improvements geared at achieving program aims and taking the program to the next level. Additionally, conducting residency and fellowship self-studies together allows for collaboration, effective use of shared resources, and the development of a cohesive educational mission.

EGID is a known post-transplant complication. Its etiology has been related to antirejection medication, but other factors may also play a role as only few transplant recipients develop EGID despite standardized treatment. This study aimed to determine whether EGID is associated with rejection events and with a specific phenotype of the rejection-positive graft biopsies in children with solid organ transplant. All patients with liver, heart, and kidney transplant followed at our institution were included in the study. Digestive tract eosinophilia was more common in heart and liver recipients and was a rare event after renal transplantation. Subjects with EGID had higher incidence of rejection and elevated peripheral blood AEC. The first rejection event and high AEC values preceded EGID diagnosis in the majority of patients. Histologically, the initial rejection-positive graft biopsy revealed accentuated eosinophilia in EGID patients compared with non-EGID cohort, which correlated with higher blood eosinophil counts at the time of first rejection episode. Prominent graft tissue and peripheral blood eosinophilia prior to EGID diagnosis suggests a predisposition for eosinophil activation in patients with post-transplant digestive eosinophilic disorder. These parameters can be used as markers for subsequent development of EGID.

Hematopoietic stem cell transplant (HSCT) is used for treatment of both oncologic and non-oncologic conditions (e.g., thalassemia, sickle cell disease). Infertility is a known late effect of HSCT. Prepubertal status does not protect male patients from gonadotoxicity of either the chemotherapy agents used in HSCT conditioning regimens or from the effects of total body irradiation. Spermatogenesis (development of mature sperm) does not begin until puberty. Therefore, the only fertility preservation option available to a prepubertal male is testicular tissue cryopreservation (TTC), an experimental option currently offered at limited number of pediatric institutions. TTC is investigational and thus should occur as part of an institutional review board-approved research protocol. Although TTC is experimental, a recent study indicates that most parents and patients will pursue TTC when faced with a diagnosis requiring gonadotoxic therapy such as HSCT.

Differentiating proliferative nodules (PNs) from melanomas arising in congenital nevi (CN) is a considerable challenge for dermatopathologists. Most of the specimens dermatopathologists assess that deal with this differential diagnosis involve proliferations of melanocytes arising in the dermis. In this study, we compare the clinical, histologic, and molecular findings of these 2 conditions. In our database, we found 22 examples of PNs arising in the dermis of CN and 2 cases of lethal melanomas arising from the dermis/epidermis of CN of children. Importantly, we found that among dermal melanocytic proliferations arising from CN in children, PNs are far more common than lethal melanomas. Clinically, multiplicity of lesions favored a diagnosis of PNs, whereas ulceration was infrequent in PNs compared with lethal melanomas. Histologically, PNs showed several distinct patterns including expansile nodules of epithelioid melanocytes with mitotic counts lower than that seen in the melanomas (1.67 vs. 12.5 mitoses/mm), a small round blue cell pattern often highly mitotically active, neurocristic-like, blue nevus-like, a nevoid melanoma-like pattern, or an undifferentiated spindle cell pattern. The lethal melanomas both featured expansile nodules of epithelioid melanocytes with high mitotic counts (range, 5 to 20 mitoses/mm) and an ulcerated overlying epidermis. At the molecular level, the PNs showed mostly whole chromosomal copy number aberrations, which in some cases were accompanied by rare partial chromosomal aberrations, whereas both lethal melanomas showed highly elevated copy number aberrations involving 6p25 without gains of the long arm of chromosome 6.

BACKGROUND AND AIMS: Over the last decade, clinical experiences and research studies raised concerns regarding use of proton pump inhibitors (PPIs) as part of the diagnostic strategy for eosinophilic esophagitis (EoE). We aimed to clarify the use of PPIs in the evaluation and treatment of children and adults with suspected EoE in order to develop updated international consensus criteria for EoE diagnosis. METHODS: A consensus conference was convened to address the issue of PPI use for esophageal eosinophilia using a process consistent with standards described in the Appraisal of Guidelines for Research and Evaluation II. Pediatric and adult physicians and researchers from gastroenterology, allergy, and pathology subspecialties representing 14 countries utilized on-line communications, teleconferences, and a face-to-face meeting to review the literature and clinical experiences. RESULTS: Substantial evidence documented that PPIs reduce esophageal eosinophilia in children, adolescents and adults, with several mechanisms potentially explaining the treatment effect. Based on these findings, an updated diagnostic algorithm for EoE was developed, with removal of the PPI trial requirement. CONCLUSIONS: EoE should be diagnosed when there are symptoms of esophageal dysfunction and at least 15 eosinophils per high-power field (or ~60 eosinophils per mm(2)) on esophageal biopsy, and after a comprehensive assessment of non-EoE disorders that could cause or potentially contribute to esophageal eosinophilia. The evidence suggests that PPIs are better classified as a treatment for esophageal eosinophilia that may be due to EoE than as a diagnostic criterion, and we have developed updated consensus criteria for EoE that reflect this change.

Background Noninvasive encapsulated follicular variant of papillary thyroid carcinoma (noniEFVPTC) has low risk of adverse outcome in adults, warranting reclassification as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). In children, thyroid nodules have higher risk of malignancy and it is unknown if encapsulated FVPTC (EFVPTC) and infiltrative FVPTC (IFVPTC) tumors have different behavior. We analyzed the clinicopathologic features of follicular variant of papillary thyroid carcinoma (FVPTC) subtypes in our pediatric population to determine if noniEFVPTC has an indolent course as reported in adults. Procedure We retrospectively studied all patients diagnosed with FVPTC at our institution. The clinicopathologic characteristics of the histologic subtypes were compared. Results Eighteen patients were identified, all treated with total thyroidectomy. No significant differences in age, sex, tumor size, focality, or prior malignancy were detected between subtypes. Extrathyroidal extension had significantly higher incidence in IFVPTC (5/8) compared with EFVPTC (1/10, P = 0.03), translating in significantly more T3 tumors within IFVPTC subtype (5/8), whereas most EFVPTC cases had T1 staging (6/10, T1 vs. T3, P = 0.05). EFVPTC had significantly lower rate of lymph node involvement (N1 in 2/8) compared with IFVPTC (N1 in 8/8, P = 0.003). Only one patient diagnosed with IFVPTC developed extranodal recurrence. When noniEFVPTC and iEFVPTC were separately compared, the noninvasive form showed no propensity for invasive growth (T3 staging: 0/4 vs. 2/6), lymph node metastasis (N1: 0/3 vs. 2/5) or extranodal recurrence. Conclusion In children, noniEFVPTC/NIFTP has indolent behavior, warranting consideration of less aggressive management, similar to adults.

Pediatric renal tumors (PRT) with small round blue or spindle cell morphology can be diagnostically challenging and only a limited number of immunohistochemical markers have been documented to help in the diagnosis: paired box (Pax) 2 and nerve growth factor receptor (NGFR) positivity have been demonstrated in Wilms tumor (WT) and clear cell sarcoma of the kidney (CCSK), respectively. However, the immunohistochemical expression of these markers in other PRT remains unknown. This study investigated Pax8, Pax2, and NGFR immunophenotype in a large series of PRT. Pax8 and Pax2 showed an identical staining pattern, and were expressed in all (100%) WT while most CCSK were negative. All congenital mesoblastic nephromas, metanephric stromal tumors, primitive neuroectodermal tumors, desmoplastic small round blue cell tumors, most rhabdoid tumors, and synovial sarcomas were negative for Pax8. NGFR was expressed in 96% of CCSK (diffuse expression in 91%). Only a minority of WT stained for NGFR: 16% showed expression in the blastemal and 25% in the mesenchymal components. NGFR expression was noted in synovial sarcomas (67%, with diffuse expression seen in only 1 case, 8%), rhabdoid tumors (19%), cellular congenital mesoblastic nephromas (13%) and metanephric stromal tumors (12.5%). Primitive neuroectodermal tumors and desmoplastic small round blue cell tumors were negative for NGFR. In conclusion, Pax8/Pax2 and NGFR are sensitive markers for the diagnosis of WT and CCSK, respectively. However, their specificity is limited by variable reactivity within a subset of other renal neoplasms.

Infantile fibrosarcoma is a rare soft tissue tumor that usually presents either at birth or in the 1st year of life. Here we describe a case of a 4-month-old female who presented with a congenital right axillary mass. The initial clinical impression was benign vascular/lymphatic malformation. The core biopsy showed a spindle cell lesion with abundant vasculature represented by small vascular channels. However, immunohistochemical analysis did not support a diagnosis of vascular lesion/tumor. Polymerase chain reaction study for ETS Translocation Variant 6/neurotrophic tyrosine kinase receptor, type 3 fusion transcript was positive, and the diagnosis of infantile fibrosarcoma was established. The patient underwent resection of the axillary mass. Microscopic examination of the resection specimen showed numerous vascular channels. Intermixed there were also cellular areas composed of spindle cells similar to those seen in the biopsy material. Molecular studies were repeated and confirmed the diagnosis of infantile fibrosarcoma. Infantile fibrosarcoma has been previously reported in the literature to clinically masquerade as hemangioma. In addition, this case proves that infantile fibrosarcoma could also mimic vascular malformations on clinical, radiologic, and pathologic exams. In fact, the vascular component of the tumor is very unusual in our patient and represents a histologic feature that has not been described before. The case highlights the diagnostic challenges at clinical, radiologic, and pathologic levels in some cases of infantile fibrosarcoma and raises awareness among clinicians and pathologists related to another peculiar pattern that can be encountered in this disease.

The tumor suppressor p53 gene is mutated in minimally half of all cancers. It is therefore reasonable to assume that naturally occurring polymorphic genetic variants in the p53 stress response pathway might determine an individual's susceptibility to cancer. A central node in the p53 pathway is the MDM2 protein, a direct negative regulator of p53. In this report, a single nucleotide polymorphism (SNP309) is found in the MDM2 promoter and is shown to increase the affinity of the transcriptional activator Sp1, resulting in higher levels of MDM2 RNA and protein and the subsequent attenuation of the p53 pathway. In humans, SNP309 is shown to associate with accelerated tumor formation in both hereditary and sporadic cancers. A model is proposed whereby SNP309 serves as a rate-limiting event in carcinogenesis.

In cancer cells, the function of the tumor suppressor protein p53 is usually blocked. Impairment of the p53 pathway results in tumor cells with endogenous overexpression of Mdm2 via a naturally occurring single nucleotide polymorphism (SNP) in the mdm2 gene at position 309. Here we report that in mdm2 SNP309 cells, inactivation of p53 results in a chromatin-associated Mdm2-p53 complex without clearance of p53 by protein degradation. Nuclear accumulation of p53 protein in mdm2 SNP309 cells results after 6 h of camptothecin, etoposide, or mitomycin C treatment, with the p53 protein phosphorylated at Ser15. Chromatin immunoprecipitation demonstrated p53 and Mdm2 bound to p53 responsive elements. Interestingly, although the p53 protein was able to bind to DNA, quantitative PCR showed compromised transcription of endogenous target genes. Additionally, exogenously introduced p53 was incapable of activating transcription from p53 responsive elements in SNP309 cells, confirming the trans-acting nature of the inhibitor. Inhibition of Mdm2 by siRNA resulted in transcriptional activation of these p53 targets. Our data suggest that overproduction of Mdm2, resulting from a naturally occurring SNP, inhibits chromatin-bound p53 from activating the transcription of its target genes.

Bone lesions, both neoplastic and non-neoplastic, are common in children. The accurate diagnosis is usually established following tissue sampling with histopathologic examination. However, those entities with predominant small round blue cell morphology can be diagnostically challenging. This review highlights distinctive morphologic and molecular features that can help pathologists when encountering these cases.

10-Decarbamoyl-mitomycin C (DMC), a mitomycin C (MC) derivative, generates an array of DNA monoadducts and interstrand cross-links stereoisomeric to those that are generated by MC. DMC was previously shown in our laboratory to exceed the cytotoxicity of MC in a human leukemia cell line that lacks a functional p53 pathway (K562). However, the molecular signal transduction pathway activated by DMC–DNA adducts has not been investigated. In this study, we have compared molecular targets associated with signaling pathways activated by DMC and MC in several human cancer cell lines. In cell lines lacking wild-type p53, DMC was reproducibly more cytotoxic than MC, but it generated barely detectable signal transduction markers associated with apoptotic death. Strikingly, DMC’s increased cytotoxicity was not associated with an increase in DNA double-strand breaks but was associated with early poly(ADP-ribose) polymerase (PARP) activation and Chk1 kinase depletion. Alkylating agents can induce increased PARP activity associated with programmed necrosis, and the biological activity of DMC in p53-null cell lines fits this paradigm. In cell lines with a functional p53 pathway, both MC and DMC induced apoptosis. In the presence of p53, both MC and DMC activate procaspases; however, the spectrum of procaspases involved differs for the two drugs, as does induction of p73. These studies suggest that in the absence of p53, signaling to molecular targets in cell death can shift in response to different DNA adduct structures to induce non-apoptotic cell death.

Epstein-Barr virus (EBV) has oncogenic potential and has been implicated in the etiology of a wide range of malignancies. Certain EBV-driven neoplasms, such as smooth muscle tumors (SMTs), manifest typically in immunocompromised patients. In children, these neoplasms have been encountered in the setting of primary immune disorders, specifically severe combined and common variable immunodeficiency syndromes. Human immunodeficiency virus infection and posttransplant immunosuppression, in particular liver and kidney transplantation, likewise increase the risk in the pediatric population. The location of these neoplasms appears related to the type of immunodeficiency: in acquired immunodeficiency syndrome they are frequently located intracranially or intraspinally, whereas after transplant they usually involve the liver or lung. We report 2 distinct cases of EBV-related SMT, unique through their coassociated immunosuppressive state or location: the 1st occurred in a patient with immunodeficiency secondary to NEMO gene mutation following hematopoietic stem cell transplantation; the 2nd developed in the orbit after heart transplant.

Since the discovery of coronins in 1991 significant research has been carried out to understand their molecular structure and cellular mechanisms of the action. While a number of binding partners have been discovered, the precise mechanisms of action of Coronin-1A are still being elucidated, both in vitro and in vivo. The role of Coronin-1A in the development and function of the immune system is irrefutable, in both humans and mice, and deficiency of Coronin-1A results in CID. Although some immunological manifestations of Coronin-1A deficiency differed between the patients described so far, absence of Coronin-1A affected the T cell compartment in all patients. B cell numbers were lower than normal and antibody responses were impaired. Variable NK cell defects associated with absent Coronin-1A to date will require detailed analysis of further patients. HCT was curative for patients with Coronin-1A deficiency when the disease was diagnosed early, before onset of irreversible complications arising from infections and EBV associated malignancy. With new evidence about the potential of anti-Coronin-1A monoclonal antibodies to treat B cell malignancies and T cell-mediated auto-inflammatory diseases, Coronin-1A can now be said to be involved in the overall regulation of the immune system, and inappropriate expression can lead to either immune deficiency or autoimmunity.

Background The current literature suggests that approximately 5% to 10% of melanonychia striata cases in adults are the result of subungual melanoma. Objective We sought to evaluate the clinical and histopathologic features and to determine the outcomes and causes of melanonychia striata in a cohort of children. Methods We assessed 30 childhood cases of melanonychia striata for features typically associated with melanoma such as Hutchinson sign, width of the pigmented band, evolution, color, and nail dystrophy. We assessed the histopathology of lesional biopsy specimens, including melanocyte counts and suprabasal movement of melanocytes. Clinical follow-up information was reviewed when available. Results Histopathologic diagnoses included subungual lentigo in 20 cases, subungual nevus in 5 cases, and atypical melanocytic hyperplasia in 5 cases. Although a number of cases exhibited worrisome clinical or histopathologic features, none showed evidence of aggressive behavior or warranted a diagnosis of melanoma. Limitations The sample size and follow-up times are limited. Conclusions Melanonychia striata is typically associated with benign stable melanocytic proliferations in childhood. The overwhelming majority of cases can be managed conservatively. Biopsy is required in select cases.

In children the percentage of “Atypia of undetermined significance/follicular lesion of undetermined significance” (“AUS/FLUS”) cases is greater and the risk of malignancy is higher than expected. Our study aimed to determine if cytologically atypical nodules can be better characterized using imaging techniques for appropriate management of pediatric patients.Thyroid fine needle aspiration (FNA) specimens were reclassified using the Bethesda System for Reporting Thyroid Cytopathology (BSRTC). Cytologic-histologic correlation was performed to determine if the cytopathologic groups had different associations with the surgical outcome. The “AUS/FLUS” lesions were then subdivided based on radiologic features and the outcome was analyzed for each subgroup.Histologically benign follicular nodules showed uniform distribution between the “benign” vs. “AUS/FLUS” (p=0.09) or between the “AUS/FLUS” vs. “follicular neoplasm” (“FN”) cytologic groups (p=0.27). The follicular neoplasms were also evenly distributed between the “FN” vs. “AUS/FLUS” categories (p=0.31). “Benign”, “AUS/FLUS”, and “FN” designations showed comparable associations with papillary thyroid carcinoma classical variant (PTC-cv). Reclassification of atypical lesions based on ultrasound findings yielded two subcategories with different risk of malignancy: one similar to the “benign” group (11% malignancy rate) and one comparable with the “FN” category (28% risk of malignant neoplasm).“AUS/FLUS” designation does not add significant value in categorization of pediatric thyroid nodules. These lesions can be reclassified based on radiologic features to provide accurate information for follow-up.

Biliary atresia is an inflammatory cholangiopathy of still undetermined etiology. Correlations between histologic findings and clinical outcome in this disease have largely been based on evaluation of liver parenchyma. This study aimed to characterize the pattern of inflammation within the biliary remnant and identify associations between the type and degree of inflammation and clinical outcome as reflected by the transplant-free interval. The inflammation within the fibrous plates and livers of 41 patients with biliary atresia was characterized using immunohistochemical markers and the cell populations were digitally quantified. The type and quantity of cells within the infiltrate were then correlated with length of time from Kasai portoenterostomy until transplant. Histologic and immunohistochemical features of the biliary remnant allowed stratification of patients into "inflammatory plate" and "fibrotic plate" groups. Overall there was no significant difference in transplant-free interval between the two cohorts; however, there was a trend towards a longer time to transplant among patients in the "fibrotic plate" group. In addition, the composition of the inflammatory infiltrate in the fibrous plate was distinctly different from that present in the liver and only the characteristics of the inflammation in the fibrous plate, in particular the number of Foxp3+ T regulatory lymphocytes correlated with clinical outcome. The results of this study support the view of the extra-hepatic biliary tree as the primary site of injury in BA with the changes seen in the liver as secondary manifestations of outflow obstruction. The association between specific inflammatory cell subtypes within the fibrous plate and the length of transplant-free interval also supports the role of the immune system in the initial process of bile duct damage in biliary atresia.