Can Dynamic Contrast-Enhanced MRI Be Used to Differentiate Hepatic Hemangioma from Other Lesions in Early Infancy?

Background Confident diagnosis of hepatic hemangioma on imaging can avoid biopsy in early infancy and helps guide conservative management. Purpose This article aims to determine if dynamic contrast-enhanced magnetic resonance imaging (MRI) can be used to differentiate liver hemangioma from other lesions in infants ≤ 100 days and to determine association of MRI features with hepatic lesions. Methods MRI performed for liver lesions were retrospectively reviewed to note imaging characteristics and the MRI diagnosis. Final diagnosis was assigned based on pathology in available cases and by corroborative standard of reference including overall clinical features, lab findings, and follow-up. Results Of 30 infants (18 boys, 12 girls; average age 42.2 days) included, 18 had solitary and 12 had multifocal lesions. Diagnoses in total 33 lesions included hemangiomas (23), hepatoblastoma (6), arteriovenous malformation (2), neuroblastoma metastases (1), and infarction (1). MRI and final diagnosis matched in 94% lesions with almost perfect agreement (kappa 0.86) for reader 1, and matched in 88% lesions with substantial agreement (kappa 0.71) for reader 2. Interobserver agreement for MRI diagnosis was substantial (kappa 0.62). Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MRI in differentiating hemangioma from other lesions were 100, 90, 96, 100, and 97%, respectively. Centripetal (16/23) or flash (5/23) filling were only seen with hemangioma. There was no significant difference in alpha-fetoprotein elevation ( p 0.08), average size ( p 0.35), multifocality ( p 0.38), and intralesional hemorrhage ( p 1) between hemangioma and hepatoblastoma. Conclusion Centripetal filling on dynamic imaging and absence of washout are characteristic MRI features of hepatic hemangioma that can help to differentiate it from other lesions in early infancy.

Isolation and adipogenic differentiation of murine mesenchymal stem cells harvested from macrophage-depleted bone marrow and adipose tissue.

INTRODUCTION AND PURPOSE: Mouse mesenchymal stem cells (MSCs) provide a resourceful tool to study physiological and pathological aspects of adipogenesis. Bone marrow-derived MSCs (BM-MSCs) and adipose tissue-derived MSCs (ASCs) are widely used for these studies. Since there is a wide spectrum of methods available, the purpose is to provide a focused hands-on procedural guide for isolation and characterization of murine BM-MSCs and ASCs and to effectively differentiate them into adipocytes. METHODS AND RESULTS: Optimized harvesting procedures for murine BM-MSCs and ASCs are described and graphically documented. Since macrophages reside in bone-marrow and fat tissues and regulate the biological behaviour of BM-MSCs and ASCs, we included a procedure to deplete macrophages from the MSC preparations. The identity and stemness of BM-MSCs and ASCs were confirmed by flow cytometry using established markers. Since the composition and concentrations of adipogenic differentiation cocktails differ widely, we present a standardized four-component adipogenic cocktail, consisting of insulin, dexamethasone, 3-isobutyl-1-methylxanthine, and indomethacin to efficiently differentiate freshly isolated or frozen/thawed BM-MSCs and ASCs into adipocytes. We further included visualization and quantification protocols of the differentiated adipocytes. CONCLUSION: This laboratory protocol was designed as a step-by-step procedure for harvesting murine BM-MSCs and ASCs and differentiating them into adipocytes.

Imaging of pediatric gastrointestinal tumors: A tertiary center experience over 19 years.

PURPOSE: Gastrointestinal tract (GIT) tumors in children are rare and there is a scarcity of data on their imaging features. The purpose of this study was to determine thefrequency of various GIT tumor types in children and to identify key imaging characteristics. METHODS: This retrospective, single-center study was approved by the local ethics committee. Children with histologically proven GIT tumours (malignantand benign) who had imaging available on the institutional PACS between May 1, 2000 and Dec 31, 2019 were included. Demographic data and available imaging was reviewed by two blinded radiologists. RESULTS: In total, 90 children (45 male, mean age 9.3 ± 4.3 years) with GIT tumours were included. The final diagnoses included polyps (n = 28), lymphomas/PTLD (n = 27), neuroendocrine tumours (n = 16), adenocarcinoma (n = 6), adenoma (n = 5), gastrointestinal stromal tumor (GIST) (n = 3), inflammatory myofibroblastic tumours (n = 2) and lastly leiomyoblastoma, leiomyoma and lipoma (1 each). All GIT segments were affected, but overall the small and large bowel had most lesions. Eighty-one percent children had a single lesion while remaining 19 % had multiple lesions. The neoplastic process manifested as intra-luminal lesion (58 %) or wall thickening (42 %) on imaging. Multiple cystic areas and vascular pedicle for polyps; and hypoechogenecity of the mass or wall thickening and aneurysmal dilatation for lymphomas, were the characteristic imaging features. None of the neuroendocrine tumours affecting appendix were seen on pre-resection imaging. CONCLUSIONS: Variety of benign and malignant tumors are seen throughout the childhood. Polyps, lymphomas and appendiceal neuroendocrine tumors are common lesions. Characteristic imaging features of juvenile polyps and lymphomas on ultrasound may help narrowing the differentials, and guide further work up.

The genomic and evolutionary landscapes of anaplastic thyroid carcinoma.

Anaplastic thyroid carcinoma is arguably the most lethal human malignancy. It often co-occurs with differentiated thyroid cancers, yet the molecular origins of its aggressivity are unknown. We sequenced tumor DNA from 329 regions of thyroid cancer, including 213 from patients with primary anaplastic thyroid carcinomas. We also whole genome sequenced 9 patients using multi-region sequencing of both differentiated and anaplastic thyroid cancer components. Using these data, we demonstrate thatanaplastic thyroid carcinomas have a higher burden of mutations than other thyroid cancers, with distinct mutational signatures and molecular subtypes. Further, different cancer driver genes are mutated in anaplastic and differentiated thyroid carcinomas, even those arising in a single patient. Finally, we unambiguously demonstrate that anaplastic thyroid carcinomas share a genomic origin with co-occurring differentiated carcinomas and emerge from a common malignant field through acquisition of characteristic clonal driver mutations.

Use of a combined transient elastography and biochemical strategy to determine liver fibrosis in pediatric intestinal failure.

BACKGROUND & AIMS: Non-invasive monitoring of intestinal failure (IF) associated liver disease is an ongoing challenge in children with IF. Our objective was to develop a combined algorithm of clinical, transient elastography (TE) and biochemical parameters to identify liver fibrosis in this population. METHODS: A retrospective cohort study of IF patients followed by our intestinal rehabilitation program between November 2015 to October 2019. Patients with a liver biopsy and TE were included. Demographic and liver function tests were collected. Fibrosis on liver biopsies was graded using the modified Scheuer score. Decision tree based algorithms classified low (F0-F1) versus high (F2-F4) fibrosis scores based on a combination of TE, biochemical and demographic parameters, using 6-fold classification error, sensitivity and specificity cross-validation (CV) scores. RESULTS: 42 patients (74% male, median age 7.6 (4.6; 42.7) months) were evaluated. Median length of PN therapy was 182 (121; 556) days. High fibrosis was present in 40.5% with a median TE of 12.1 (6.7; 12.9) kPa in high fibrosis children. An algorithm, based on cut-off values for TE of 11.3 kPa and AST of 40 U/L, and grouping of the underlying etiology resulted in a correct classification of 88.1% of the pathology scores; with sensitivity 0.82 (95% CI 0.57; 0.96), specificity 0.92 (95% CI 0.74; 0.99), positive predictive value 0.88 (95% CI 0.64; 0.96) and negative predictive value 0.88 (95% CI 0.73; 0.96). The CV classification error was 28.6%, CV sensitivity 72.2% and CV specificity 75.5%. CONCLUSIONS: This algorithm shows promising results that could simplify non-invasive monitoring of liver fibrosis in children with IF. Validation in additional IF cohorts is needed.

Precision cut intestinal slices, a novel model of acute food allergic reactions.

BACKGROUND: Food allergy affects up to 10% of the pediatric population. Despite ongoing efforts, treatment options remain limited. Novel models of food allergy are needed to study response patterns downstream of IgE-crosslinking and evaluate drugs modifying acute events. Here, we report a novel human ex vivo model that displays acute, allergen-specific, IgE-mediated smooth muscle contractions using precision cut intestinal slices (PCIS). METHODS: PCIS were generated using gut tissue samples from children who underwent clinically indicated surgery. Viability and metabolic activity were assessed from 0 to 24 h. Distribution of relevant cell subsets was confirmed using single nucleus RNA sequencing. PCIS were passively sensitized using plasma from peanut allergic donors or peanut-sensitized non-allergic donors, and exposed to various stimuli including serotonin, histamine, FcɛRI-crosslinker, and food allergens. Smooth muscle contractions and mediator release functioned as readouts. A novel program designed to measure contractions was developed to quantify responses. The ability to demonstrate the impact of antihistamines and immunomodulation from peanut oral immunotherapy (OIT) was assessed. RESULTS: PCIS viability was maintained for 24 h. Cellular distribution confirmed the presence of key cell subsets including mast cells. The video analysis tool reliably quantified responses to different stimulatory conditions. Smooth muscle contractions were allergen-specific and reflected the clinical phenotype of the plasma donor. Tryptase measurement confirmed IgE-dependent mast cell-derived mediator release. Antihistamines suppressed histamine-induced contraction and plasma from successful peanut OIT suppressed peanut-specific PCIS contraction. CONCLUSION: PCIS represent a novel human tissue-based model to study acute, IgE-mediated food allergy and pharmaceutical impacts on allergic responses in the gut.

Digital quantitative tissue image analysis of hypoxia in resected pancreatic ductal adenocarcinomas.

Background: Tumor hypoxia is theorized to contribute to the aggressive biology of pancreatic ductal adenocarcinoma (PDAC). We previously reported that hypoxia correlated with rapid tumor growth and metastasis in patient-derived xenografts. Anticipating a prognostic relevance of hypoxia in patient tumors, we developed protocols for automated semi-quantitative image analysis to provide an objective, observer-independent measure of hypoxia. We further validated this method which can reproducibly estimate pimonidazole-detectable hypoxia in a high-through put manner. Methods: We studied the performance of three automated image analysis platforms in scoring pimonidazole-detectable hypoxia in resected PDAC (n = 10) in a cohort of patients enrolled in PIMO-PANC. Multiple stained tumor sections were analyzed on three independent image-analysis platforms, Aperio Genie (AG), Definiens Tissue Studio (TS), and Definiens Developer (DD), which comprised of a customized rule set. Results: The output from Aperio Genie (AG) had good concordance with manual scoring, but the workflow was resource-intensive and not suited for high-throughput analysis. TS analysis had high levels of variability related to misclassification of cells class, while the customized rule set of DD had a high level of reliability with an intraclass coefficient of more than 85%. Discussion: This work demonstrates the feasibility of developing a robust, high-performance pipeline for an automated, quantitative scoring of pimonidazole-detectable hypoxia in patient tumors.

Hepatic ultrastructural features distinguish paediatric Wilson disease from NAFLD and autoimmune hepatitis.

BACKGROUND AND AIMS: Wilson disease (WD) has diverse presentations that frequently mimic other liver diseases. Distinguishing WD from non-alcoholic fatty liver disease (NAFLD) and autoimmune hepatitis (AIH), can be difficult and has critical implications for medical management. This study aimed to examine the utility of histological features of WD in children compared to those with NAFLD and AIH. METHODS: A review of liver biopsy slides was performed in children with a clinical and/or genetic diagnosis of WD, seen at the Hospital for Sick Children between 1981 and 2019 and compared to controls with NAFLD and AIH. 37 children with WD and 37 disease controls (20 NAFLD; 17 AIH) were included. Three pathologists, blind to clinical details and diagnosis, reviewed all liver biopsies to reach consensus. Clinical and histopathologic features were compared between groups. RESULTS: Most WD cases displayed steatosis or steatohepatitis on histology (34/37), active AIH-pattern in 1 and inactive cirrhosis in 2 cases. Electron microscopy (EM) findings of mitochondrial abnormalities including dilated tips of cristae, pleomorphism, membrane duplication and dense matrix were more frequent in the WD group as compared to disease controls (p < 0.0001). In WD, dilated tips of mitochondrial cristae had a sensitivity of 91% and specificity of 86%, best among EM features. CONCLUSIONS: Light microscopic findings display considerable overlap among children with WD, NAFLD and AIH. Ultrastructural findings of mitochondrial abnormalities are important to distinguish WD from NAFLD and AIH. EM examination should be considered essential in the diagnostic work-up of paediatric liver biopsies.

Prospective Evaluation of Endoscopic and Histologic Indices in Pediatric Ulcerative Colitis Using Centralized Review.

INTRODUCTION: We aimed to evaluate the reliability and validity of the Ulcerative Colitis (UC) Endoscopic Index of Severity (UCEIS) and Mayo Endoscopy Score (MES) and to validate the Robarts Histopathology Index (RHI) and Nancy Index (NI) in pediatric UC. We examined rectosigmoid and pancolonic versions of each instrument. METHODS: Single-center cross-sectional study of 60 prospectively enrolled participants. Through central endoscopy review, 4 pediatric gastroenterologists assigned rectosigmoid and pancolonic (mean of 5 colonic segments) UCEIS and MES scores. Two blinded pathologists assigned rectosigmoid and pancolonic RHI and NI scores. We assessed reliability with intraclass correlation coefficients and weighted kappa statistics and explored construct validity with correlations, boxplots, and receiver operator characteristic curves. RESULTS: The UCEIS and MES displayed almost perfect intra-rater and inter-rater reliability (intraclass correlation coefficient and weighted kappa ≥0.85), moderate-to-strong correlation with histologic/clinical activity and fecal calprotectin (FC), and very strong correlation with global endoscopic severity (r > 0.9). Rectosigmoid UCEIS and MES scores of 0 were highly specific (≥95%) for endoscopic and histologic remission throughout the colon. Pancolonic endoscopy scores correlated more strongly with histologic activity, clinical activity, and systemic inflammatory markers and better discriminated between degrees of active disease. RHI and NI showed moderate-to-strong correlation (r = 0.5-0.83) with endoscopic/clinical activity and FC. DISCUSSION: Our findings support the reliability and construct validity of the UCEIS and MES and the construct validity of the RHI and NI in pediatric UC. Normal rectosigmoid findings predicted pancolonic healing, but, given active disease, pancolonic endoscopic assessment more accurately captured global disease burden.

Sequential paternal haploidentical donor liver and HSCT in EPP allow discontinuation of immunosuppression post-organ transplant.

BACKGROUND: EPP is characterized by photosensitivity and by liver disease. When LT is performed in EPP, recurrence often occurs in the allograft due to ongoing protoporphyrin production in bone marrow. Therefore, curative treatment requires allogeneic HSCT after LT. Long-term immunosuppression could be spared by using the same donor for both transplants. METHODS: A 2-year-old girl with EPP in liver failure underwent liver transplant from her father. Transfusion and apheresis therapy were used to lower protoporphyrin levels before and after liver transplant. Ten weeks after liver transplant, she underwent HSCT, using the same donor. Conditioning was with treosulfan, fludarabine, cyclophosphamide, and ATG. GVHD prophylaxis was with abatacept, methotrexate, MMF, and tacrolimus. We followed the patient's erythrocyte protoporphyrin and liver and skin health for 2 years after transplant. RESULTS: After hematopoietic stem cell engraftment, a decline in protoporphyrin levels was observed, with clinical resolution of photosensitivity. Liver biopsies showed no evidence of EPP. Mild ACR occurred and responded to steroid pulse. Two years post-HSCT, the patient has been weaned off all immunosuppression and remains GVHD and liver rejection free. CONCLUSIONS: Sequential liver and HSCT from the same haploidentical donor are feasible in EPP. This strategy can allow for discontinuation of immune suppression.

Gain-of-function variants in SYK cause immune dysregulation and systemic inflammation in humans and mice.

Spleen tyrosine kinase (SYK) is a critical immune signaling molecule and therapeutic target. We identified damaging monoallelic SYK variants in six patients with immune deficiency, multi-organ inflammatory disease such as colitis, arthritis and dermatitis, and diffuse large B cell lymphomas. The SYK variants increased phosphorylation and enhanced downstream signaling, indicating gain of function. A knock-in (SYK-Ser544Tyr) mouse model of a patient variant (p.Ser550Tyr) recapitulated aspects of the human disease that could be partially treated with a SYK inhibitor or transplantation of bone marrow from wild-type mice. Our studies demonstrate that SYK gain-of-function variants result in a potentially treatable form of inflammatory disease.

Imaging and clinical features of pediatric hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is rare in children and there is limited data on its imaging features. OBJECTIVE: To describe imaging features of pediatric HCC and correlate them with clinical and laboratory findings. MATERIALS AND METHODS: We retrospectively reviewed imaging in all pediatric HCC cases seen between January 2000 and January 2019. Imaging features defined in LI-RADS (Liver Imaging Reporting and Data System) and tumor extent by PRETEXT (pretreatment extent of disease) criteria were noted by two radiologists. Patient charts were reviewed to collect clinical features, alpha-fetoprotein (AFP) level and pathology findings. RESULTS: Of the 15 children (7 boys, 8 girls; mean age: 11.8 years, age range: 6-17 years) included in the study, 12/15 had computed tomography, 9/15 had magnetic resonance imaging and 9/15 had ultrasound exams available for review. Pathological types of HCC included classic (11/15, 73%), fibrolamellar (3/15, 20%) and mixed cholangiocarcinoma-HCC (1/15, 7%). Eighty percent occurred de novo in normal liver and 67% showed elevated AFP levels. Arterial phase hyperenhancement was seen in 83% of cases, washout in 86%, capsule in 50% and tumor-in-vein in 33%. The mean tumor size was 9.8 cm and 40% were multifocal on imaging. Staging revealed PRETEXT II tumors in 47%, III in 20% and IV in 33%. There were no PRETEXT I tumors. The two most common PRETEXT annotation factors were portal vein and caudate lobe involvement in 71% and 43% of cases, respectively. Fibrolamellar HCC demonstrated central scar, normal AFP levels and normal background liver. CONCLUSION: Pediatric HCC are large heterogeneous tumors, as reflected by high PRETEXT staging, and commonly include portal vein and caudate involvement. This affects resectability of these tumors at presentation. Central scar, normal AFP level and normal liver background may help differentiate fibrolamellar HCC from other types of HCC.

Accurate Classification of Pediatric Colonic Inflammatory Bowel Disease Subtype Using a Random Forest Machine Learning Classifier.

BACKGROUND: The pediatric inflammatory bowel disease (PIBD) classes algorithm was developed to bring consistency to labelling of colonic IBD, but labels are exclusively based on features atypical for ulcerative colitis (UC). AIM: The aim of the study was to develop an algorithm and identify features that discriminate between pediatric UC and colonic Crohn disease (CD). METHODS: Baseline clinical, endoscopic, radiologic, and histologic data, including the PIBD class features in 74 colonic IBD (56: UC, 18: colonic CD) patients were collected. The PIBD class features and additional features common to UC were used to perform initial clustering, using similarity network fusion (SNF). We trained a Random Forest (RF) classifier on the full dataset and used a leave-one-out approach to evaluate model accuracy. The top-features were used to build a new classifier, which we tested on 15 previously unused patients. We then performed clustering with SNF on the top RF features and assessed ability to discriminate between UC and colonic-CD independent of a supervised model. RESULTS: The initial SNF clustering with 58 patients demonstrated 2 groups: group 1 (n = 39, 90% UC) and group 2 (n = 19, 68% colonic-CD). Our RF classifier correctly labelled 97% of the 58 patients based on leave-one-out cross validation and identified the 7 most important features (3 histological and 4 endoscopic) to clinically distinguish these groups. We trained a new RF classifier with the top 7 features and found 100% accuracy in a set of 15 held-out patients. Finally, post hoc clustering with these 7 features revealed 2 groups of patients: group 1 (n = 55, 98% UC) and group 2 (n = 18, 94% colonic-CD). CONCLUSIONS: A combination of supervised and unsupervised analyses identified a short list of features, which consistently distinguish UC from colonic CD. Future directions include validation in other populations.

Cancers from Novel Pole-Mutant Mouse Models Provide Insights into Polymerase-Mediated Hypermutagenesis and Immune Checkpoint Blockade.

POLE mutations are a major cause of hypermutant cancers, yet questions remain regarding mechanisms of tumorigenesis, genotype-phenotype correlation, and therapeutic considerations. In this study, we establish mouse models harboring cancer-associated POLE mutations P286R and S459F, which cause rapid albeit distinct time to cancer initiation in vivo, independent of their exonuclease activity. Mouse and human correlates enabled novel stratification of POLE mutations into three groups based on clinical phenotype and mutagenicity. Cancers driven by these mutations displayed striking resemblance to the human ultrahypermutation and specific signatures. Furthermore, Pole-driven cancers exhibited a continuous and stochastic mutagenesis mechanism, resulting in intertumoral and intratumoral heterogeneity. Checkpoint blockade did not prevent Pole lymphomas, but rather likely promoted lymphomagenesis as observed in humans. These observations provide insights into the carcinogenesis of POLE-driven tumors and valuable information for genetic counseling, surveillance, and immunotherapy for patients. SIGNIFICANCE: Two mouse models of polymerase exonuclease deficiency shed light on mechanisms of mutation accumulation and considerations for immunotherapy.See related commentary by Wisdom and Kirsch p. 5459.

Liver transplantation for Gaucher disease presenting as neonatal cholestasis: Case report and literature review.

BACKGROUND: We present a rare case of neonatal cholestasis in a female infant with Gaucher Disease (GD), who received liver transplantation. We review the relevant literature on similar disease presentations. METHODS: A chart review of the index case was performed. PubMed and Medline databases were searched to identify other cases. RESULTS: A 4-day-old female was referred with conjugated hyperbilirubinemia. Physical examination revealed icterus with hepatosplenomegaly and normal neurologic examination. The diagnosis of GD was confirmed through liver biopsy, low glucocerebrosidase enzyme activity, and two pathogenic mutations in GBA gene. Despite early initiation of ERT, the patient had worsening of her liver failure and underwent a left lateral segment liver transplant from a living donor at 7 months of age. She experienced improvement of her liver enzymes and coagulation, but passed away at 8 months due to the late onset of neurologic involvement. Nine other cases of GD presenting with neonatal cholestasis have been reported. Forty-four percent (4/9) of cases received ERT and none were considered for transplant. Overall, the literature suggests a poor prognosis with death reported in 77% (7/9) cases. CONCLUSIONS: Neonatal presentation of GD represents a poor prognosis despite early initiation of treatment. Diagnosis remains a challenge as the presentation is rare and multiple tests such as BM biopsy, liver biopsy with both light and electron microscopy, enzymology, and genetic testing may need to be completed to reach a diagnosis. Neurological sequelae may manifest later making the decision to proceed with liver transplantation a difficult one.

Quantifying Reoxygenation in Pancreatic Cancer During Stereotactic Body Radiotherapy.

Hypoxia, the state of low oxygenation that often arises in solid tumours due to their high metabolism and irregular vasculature, is a major contributor to the resistance of tumours to radiation therapy (RT) and other treatments. Conventional RT extends treatment over several weeks or more, and nominally allows time for oxygen levels to increase ("reoxygenation") as cancer cells are killed by RT, mitigating the impact of hypoxia. Recent advances in RT have led to an increase in the use stereotactic body radiotherapy (SBRT), which delivers high doses in five or fewer fractions. For cancers such as pancreatic adenocarcinoma for which hypoxia varies significantly between patients, SBRT might not be optimal, depending on the extent to which reoxygenation occurs during its short duration. We used fluoro-5-deoxy-α-D-arabinofuranosyl)-2-nitroimidazole positron-emission tomography (FAZA-PET) imaging to quantify hypoxia before and after 5-fraction SBRT delivered to patient-derived pancreatic cancer xenografts orthotopically implanted in mice. An imaging technique using only the pre-treatment FAZA-PET scan and repeat dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) scans throughout treatment was able to predict the change in hypoxia. Our results support the further testing of this technique for imaging of reoxygenation in the clinic.

Prevalence and Clinical Features of Inflammatory Bowel Diseases Associated With Monogenic Variants, Identified by Whole-Exome Sequencing in 1000 Children at a Single Center.

BACKGROUND & AIMS: A proportion of infants and young children with inflammatory bowel diseases (IBDs) have subtypes associated with a single gene variant (monogenic IBD). We aimed to determine the prevalence of monogenic disease in a cohort of pediatric patients with IBD. METHODS: We performed whole-exome sequencing analyses of blood samples from an unselected cohort of 1005 children with IBD, aged 0-18 years (median age at diagnosis, 11.96 years) at a single center in Canada and their family members (2305 samples total). Variants believed to cause IBD were validated using Sanger sequencing. Biopsies from patients were analyzed by immunofluorescence and histochemical analyses. RESULTS: We identified 40 rare variants associated with 21 monogenic genes among 31 of the 1005 children with IBD (including 5 variants in XIAP, 3 in DOCK8, and 2 each in FOXP3, GUCY2C, and LRBA). These variants occurred in 7.8% of children younger than 6 years and 2.3% of children aged 6-18 years. Of the 17 patients with monogenic Crohn's disease, 35% had abdominal pain, 24% had nonbloody loose stool, 18% had vomiting, 18% had weight loss, and 5% had intermittent bloody loose stool. The 14 patients with monogenic ulcerative colitis or IBD-unclassified received their diagnosis at a younger age, and their most predominant feature was bloody loose stool (78%). Features associated with monogenic IBD, compared to cases of IBD not associated with a single variant, were age of onset younger than 2 years (odds ratio [OR], 6.30; P = .020), family history of autoimmune disease (OR, 5.12; P = .002), extra-intestinal manifestations (OR, 15.36; P < .0001), and surgery (OR, 3.42; P = .042). Seventeen patients had variants in genes that could be corrected with allogeneic hematopoietic stem cell transplantation. CONCLUSIONS: In whole-exome sequencing analyses of more than 1000 children with IBD at a single center, we found that 3% had rare variants in genes previously associated with pediatric IBD. These were associated with different IBD phenotypes, and 1% of the patients had variants that could be potentially corrected with allogeneic hematopoietic stem cell transplantation. Monogenic IBD is rare, but should be considered in analysis of all patients with pediatric onset of IBD.

Differentiation of Colonic Inflammatory Bowel Disease: Re-examination of Paediatric Inflammatory Bowel Disease Classes Algorithm With Resected Colon As the Criterion Standard.

OBJECTIVES: Differentiation of Crohn disease (CD) from ulcerative colitis (UC) is challenging when inflammation is predominantly colonic. The paediatric inflammatory bowel disease (PIBD) classes algorithm was developed to bring consistency to labelling, but used physician-assigned diagnosis as the criterion standard. We aimed to reassess the PIBD classes using pathology of subsequently resected colon as the criterion standard. METHOD: Single-centre study of patients diagnosed with colonic IBD between 2002 and 2017 and subsequently treated with colectomy. Baseline pretreatment data were reviewed and the PIBD classes algorithm was independently applied by 2 reviewers to assign a label of UC/IBD-unclassified (IBD-U)/colonic-CD. Concordance between the algorithm-based, precolectomy clinical, and pathologic examination of resected colon diagnosis were assessed. Changes in diagnosis during postcolectomy follow-up were recorded. RESULTS: Sixty-two children underwent colectomy for medically refractory colonic IBD. Diagnosis based on pathologic review of resected colon CD:4;UC:56;IBDU:2. The clinical, PIBD classes algorithm, and colectomy diagnoses were concordant in 51 of 62 patients (81%, Fleiss kappa 0.48). Precolectomy clinical diagnosis was concordant with colectomy diagnosis in 58 of 62 patients (94%, weighted-kappa 0.65). The PIBD classes label was concordant with colectomy diagnosis in 51 of 62 patients (82%, weighted-kappa 0.38); resected colon pathology was typical of UC in 6 patients with PIBD classes label of IBD-U based on single class 2 feature and in 3 with PIBD classes label of CD based on single class 1 feature. CONCLUSIONS: Concordance of PIBD classes algorithm diagnosis applied before colectomy with a diagnostic label based on pathologic examination of a subsequently resected colon is only fair. Caution is needed in stringent application of colonic CD and IBD-U labels based on presence of single feature.