Pediatric Liver Transplant Pathology: An Update and Practical Consideration.

This review provides a summary of the diagnostic approach to pediatric liver transplantation (LT) pathology. It emphasizes the pathologic features of T-cell-mediated rejection, the most common finding on liver allograft biopsies, and discusses other forms of rejection, including the less frequent antibody-mediated rejection. The article incorporates insights from the recently published Banff 2022 Liver Group Meeting Report.

Challenges in Inter-rater Agreement on Lamina Propria Fibrosis in Esophageal Biopsies.

Background: Mucosal biopsies in eosinophilic esophagitis (EoE) can exhibit lamina propria (LP) fibrosis, which may portend stenotic complications; however, the histologic diagnosis of LP fibrosis is subjective. We sought to assess and improve the consistency of LP fibrosis diagnosis among our pathologist group.

Methods: At a large pediatric hospital, 25 esophageal biopsy slides from 19 patients (16 with EoE) exhibiting a wide spectrum of LP area, artifacts, and fibrosis severity were scanned into whole-slide images.

Calretinin Staining in Anorectal Line Biopsies Accurately Distinguished Hirschsprung Disease in a Retrospective Study.

Introduction: The absence of submucosal ganglion cells does not reliably distinguish Hirschsprung disease from non Hirschsprung disease in anorectal line biopsies. Calretinin staining might be helpful in these biopsies. To determine its value, we analyzed calretinin positive mucosal neurites in anorectal line biopsies.

Esophageal Fibrosis in Eosinophilic Gastrointestinal Diseases.

Objectives: Eosinophilic esophagitis (EoE), the most common eosinophilic gastrointestinal disease (EGID), is associated with lamina propria (LP) fibrosis. The relationship of EoE to other EGIDs is still unclear. We frequently observe cases of concurrent esophageal eosinophilia and extra-esophageal mucosal eosinophilia.

Epithelial Indoleamine 2,3-Dioxygenase 1 Modulates Aryl Hydrocarbon Receptor and Notch Signaling to Increase Differentiation of Secretory Cells and Alter Mucus-Associated Microbiota.

Background & Aims: Inflammation, injury, and infection up-regulate expression of the tryptophan metabolizing enzyme indoleamine 2,3-dioxygenase 1 (IDO1) in the intestinal epithelium. We studied the effects of cell-specific IDO1 expression in the epithelium at baseline and during intestinal inflammation in mice.

Methods: We generated transgenic mice that overexpress fluorescence-tagged IDO1 in the intestinal epithelium under control of the villin promoter (IDO1-TG).

Colonic Adventitial Fibromuscular Dysplasia: A Nonspecific Arteriopathy Associated With Hirschsprung Disease and Other Obstructive Disorders.

Background Smooth muscle differentiation ("adventitial fibromuscular dysplasia," AFD) was purported as specific to arteries in the transition zone of Hirschsprung disease (HSCR) patients. We investigated AFD in an HSCR population and controls and consider the pathogenesis and significance of the vascular pathology. Design Vascular histology in sections from colonic HSCR resections (n = 55) was compared with age- and site-matched controls with (n = 19) and without (n = 28) non-HSCR obstructive conditions.

Adenoid Stones - "Adenoliths".

Stones made of bacterial aggregates can be found in chronically inflamed lymphoid tissue such as hypertrophied tonsils. Although it is common to find tonsilloliths in cryptic tonsils, it is rare to find stones in adenoid tissue. Here we present an interesting case of a patient who underwent adenoidectomy for adenoid hypertrophy, recurrent malaise and upper respiratory infections.

IDO1 metabolites activate β-catenin signaling to promote cancer cell proliferation and colon tumorigenesis in mice.

Background & Aims: Indoleamine 2,3 dioxygenase-1 (IDO1) catabolizes tryptophan along the kynurenine pathway. Although IDO1 is expressed in inflamed and neoplastic epithelial cells of the colon, its role in colon tumorigenesis is not well understood. We used genetic and pharmacologic approaches to manipulate IDO1 activity in mice with colitis-associated cancer and human colon cancer cell lines.

Modeling colitis-associated cancer with azoxymethane (AOM) and dextran sulfate sodium (DSS).

Individuals with inflammatory bowel disease (IBD), such as Crohn's disease (CD) or ulcerative colitis (UC) are at increased risk of developing colorectal cancer (CRC) over healthy individuals. This risk is proportional to the duration and extent of disease, with a cumulative incidence as high as 30% in individuals with longstanding UC with widespread colonic involvement. Colonic dysplasia in IBD and colitis associated cancer (CAC) are believed to develop as a result of repeated cycles of epithelial cell injury and repair while these cells are bathed in a chronic inflammatory cytokine milieu.

Serum analysis of tryptophan catabolism pathway: correlation with Crohn's disease activity.

Background: Indoleamine 2,3 dioxygenase-1 (IDO1) is a tryptophan catabolizing enzyme with immunotolerance-promoting functions. We sought to determine if increased gut expression of IDO1 in Crohn's disease (CD) would result in detectable changes in serum levels of tryptophan and the initial IDO1 pathway catabolite, kynurenine.

Methods: Individuals were prospectively enrolled through the Washington University Digestive Diseases Research Center.