Histopathological findings from the investigation of paediatric acute hepatitis of unknown aetiology, United Kingdom 2022.

In 2022, there were global reports of increased numbers of acute hepatitis not explained by hepatitis A-E virus infection in children. This manuscript summarises histopathology results from 20 patients in the United Kingdom who underwent liver transplant or had a liver biopsy as part of aetiological investigations. All available histopathological samples were reviewed centrally as part of the outbreak investigation. A working group comprised of infection specialists, hepatologists and histopathologists met virtually to review the cases, presentation, investigations and histopathology. All 20 liver samples had evidence of inflammation without significant interface activity, and submassive confluent pan-lobular or multilobular hepatocellular necrosis. Overall, the predominant histopathological findings were of acute nonspecific hepatitis with submassive hepatic necrosis and central vein perivenulitis and endothelitis. Histopathological findings were a poor indicator of aetiology.

Barrier-Forming Potential of Epithelial Cells from the Exstrophic Bladder.

Bladder exstrophy (BEX) is a rare developmental abnormality resulting in an open, exposed bladder plate. Although normal bladder urothelium is a mitotically quiescent barrier epithelium, histologic studies of BEX epithelia report squamous and proliferative changes that can persist beyond surgical closure. The current study examined whether patient-derived BEX epithelial cells in vitro were capable of generating a barrier-forming epithelium under permissive conditions. Epithelial cells isolated from 11 BEX samples, classified histologically as transitional (n = 6) or squamous (n = 5), were propagated in vitro. In conditions conducive to differentiated tight barrier formation by normal human urothelial cell cultures, 8 of 11 BEX lines developed transepithelial electrical resistances of more than 1000 Ω.cm2, with 3 squamous lines failing to generate tight barriers. An inverse relationship was found between expression of squamous KRT14 transcript and barrier development. Transcriptional drivers of urothelial differentiation PPARG, GATA3, and FOXA1 showed reduced expression in squamous BEX cultures. These findings implicate developmental interruption of urothelial transcriptional programming in the spectrum of transitional to squamous epithelial phenotypes found in BEX. Assessment of BEX epithelial phenotype may inform management and treatment strategies, for which distinction between reversible versus intractably squamous epithelium could identify patients at risk of medical complications or those who are most appropriate for reconstructive tissue engineering strategies.

[Histological features of paediatric acute liver failure : Experiences from a tertiary referral centre for paediatric liver disease in the UK]. / Histologische Aspekte des akuten Leberversagens bei Kindern : Erfahrungen eines Überregionalen Referenzzentrums in Großbritannien.

Paediatric acute liver failure (PALF; also fulminant hepatic failure, fulminant hepatitis) is a critical clinical syndrome that is characterised by a sudden, rapid deterioration and disease progression in a usually previously healthy child. The pathogenesis is an advanced degree of hepatocellular necrosis that exceeds the rate of hepatocyte regeneration. The diagnostic criteria of PALF (modelled on adult criteria) were developed by the "Pediatric Acute Liver Failure (PALF) Study Group" (NIH). The rule of the liver biopsy in PALF is controversial and in some cases contraindicated (coagulopathic state). In addition, extensive necrosis is a common finding in PALFs but may not be predictive of the overall outcome (transplantation versus continuous treatment) due to sampling issues. There are, however, some histological patterns that offer a degree of specificity that can be carefully considered in the overall clinical picture. The histopathologists will be part of a multidisciplinary team and can contribute to the diagnostic and prognostic pathway.The aetiologies of PALF are numerous and depend on age and geographical region. For all age groups the main causes can be divided into infectious, immunological, metabolic and toxin drug related. Rarer causes include circulatory disorders and malignancies. In the paediatric group, up to 30-50% of causes leading to PALF remain unknown.

Loss of Janus Associated Kinase 1 Alters Urothelial Cell Function and Facilitates the Development of Bladder Cancer.

Inherited Primary Immunodeficiency (PID) disorders are associated with increased risk of malignancy that may relate to impaired antitumor immune responses or a direct role for PID germline mutations in tumorigenesis. We recently identified germline loss of function mutations in Janus Associated Kinase 1 (JAK1) causing primary immunodeficiency characterized by infections and associated with early onset, fatal high-grade bladder carcinoma. Somatic mutations in JAK1, required for immune cell signaling in response to interferon gamma (IFNγ), have been associated with several non-hematopoietic and hematopoietic cancer cell types but pathogenic mechanisms remain largely unexplored. Here we demonstrate that JAK1 is required for the intrinsic IFNγ response of urothelial cells impacting immunogenicity and cell survival. Specifically, JAK1-deficient urothelial cells showed reduced surface expression of major histocompatibility complex class II (MHC II), intercellular adhesion molecule-1 (ICAM-1) and programmed death-ligand-1 (PD-L1) after IFNγ stimulation and were resistant to IFNγ-induced apoptosis and lymphocyte-mediated killing. In addition, we identify a previously unknown role for IFNγ signaling in modulating urothelial differentiation. Together, our findings support a role for urothelial cell JAK1 in immune surveillance and development of bladder cancer. Our results have implications for patients with rare JAK1 PID and, more broadly, inform development of biomarker and targeted therapies for urothelial carcinoma.

A Rare Urachal Cyst in a Case of Ketamine-induced Cystitis Provides Mechanistic Insights.

OBJECTIVE: To establish whether the urothelial ulceration observed in ketamine-induced cystitis is triggered by urinary or systemic factors. This was achieved with a rare case where an urachal cyst was found near the bladder dome in a patient undergoing cystectomy for unremitting pain following ketamine abuse. METHODS: Clinical investigations included cystoscopy, video urodynamic investigation, and computed tomography of the kidneys, ureters, and bladder. Histological staining was combined with immunoperoxidase labeling for markers of transitional epithelial differentiation. RESULTS: The urachus found near the dome of the bladder was observed to be a separate cyst, with no evidence of patency found during surgery or video urodynamic investigation. The urachus was lined by a mildly reactive metaplastic epithelium of mixed transitional and columnar morphologies. Evidence of widespread cytokeratin 13, basal p75(NTR), and sparse superficial uroplakin 3a immunoreactivity suggested the urachal epithelium was fundamentally transitional in nature. Near total loss of bladder urothelium was observed from regions in contact with urine, whereas the urachal epithelium (not exposed to urine) remained healthy. CONCLUSION: This study supports the hypothesis that urinary (and not systemic) factors are the main driver of urothelial ulceration in ketamine-induced cystitis. The most likely excreted factors responsible are ketamine and potentially its metabolites. This study reinforces the importance of complete cessation of ketamine use in patients with ketamine-induced cystitis.

A fetal sheep model for studying compensatory mechanisms in the healthy contralateral kidney after unilateral ureteral obstruction.

INTRODUCTION: Fetal unilateral ureteral obstruction (UUO) triggers complex pathophysiology involving not only the affected organ but also the contralateral kidney, which undergoes evident compensatory changes. OBJECTIVE: We hypothesized that it would be possible to characterize a transcriptomic fingerprint and selected molecular mechanisms for compensatory growth of contralateral kidneys in UUO, specifically focusing on mediators, carriers, membrane transport, and organ crosstalk in an ovine fetal UUO model. STUDY DESIGN: A fetal ovine model of complete UUO was created on the 60th day of gestation. For transcriptomics profiling, total RNA was extracted from vital renal biopsies of contralateral (non-obstructed) kidneys harvested on the 80th day of gestation, and kidneys of untreated fetuses served as controls. Statistical analysis provided the set of differentially regulated genes further forwarded to bioinformatics analysis for identification of eventual compensatory molecular mechanisms. Histological analysis was performed with hematoxylin and eosin and periodic acid-Schiff stains. RESULTS: Contralateral kidneys showed compensatory hypertrophic renal growth, represented on the molecular side by 324 protein coding genes differentially regulated compared with the control kidney samples. Bioinformatics analysis identified an interactome (Figure) consisting of 102 genes with 108 interactions mainly involving transporters (protein transport and protein localization as well as in protein degradation), signaling molecules, DNA/nucleotide/RNA processing, and components of catabolism and cell cycle regulation. Within the interactome, nine receptors were identified as differentially regulated on the contralateral kidney, involving potential renoprotective ligands of the prostaglandin and the bradykinin receptor, arginine vasopressin receptor 1B, and integrin beta 4. Interestingly, a broad range of molecules found differentially expressed, has been previously described in stress response, renoprotection and repair (e.g., MAPK3, MCP1, DICER1, and others). DISCUSSION: The compensatory renal growth interactome provides a network of transcripts significantly altered in the contralateral kidney, potentially allowing novel insights into mechanisms, interactions, and signaling pathways associated with compensatory growth, and renal protection and repair. Interestingly, the finding of an embedded gene signature reflecting signaling and communication suggests a key role of these processes in CRG either by crosstalk, soluble substances, carriers, or membrane signaling. CONCLUSIONS: Using a transcriptomics approach, it was possible to identify a gene expression fingerprint of contralateral renal growth in a fetal UUO model. Further studies are warranted to validate those processes and to allow incorporation of this knowledge in new fetal diagnostic or even therapeutic strategies.

Liver disease in infancy caused by oxysterol 7 α-hydroxylase deficiency: successful treatment with chenodeoxycholic acid.

A child of consanguineous parents of Pakistani origin developed jaundice at 5 weeks and then, at 3 months, irritability, a prolonged prothrombin time, a low albumin, and episodes of hypoglycaemia. Investigation showed an elevated alanine aminotransferase with a normal γ-glutamyl-transpeptidase. Analysis of urine by electrospray ionisation tandem mass spectrometry (ESI-MS/MS) showed that the major peaks were m/z 480 (taurine-conjugated 3ß-hydroxy-5-cholenoic acid) and m/z 453 (sulphated 3ß-hydroxy-5-cholenoic acid). Analysis of plasma by gas chromatography-mass spectrometry (GC-MS) showed increased concentrations of 3ß-hydroxy-5-cholenoic acid, 3ß-hydroxy-5-cholestenoic acid and 27-hydroxycholesterol, indicating oxysterol 7 α-hydroxylase deficiency. The patient was homozygous for a mutation (c.1249C>T) in CYP7B1 that alters a highly conserved residue in oxysterol 7 α-hydroxylase (p.R417C) - previously reported in a family with hereditary spastic paraplegia type 5. On treatment with ursodeoxycholic acid (UDCA), his condition was worsening, but on chenodeoxycholic acid (CDCA), 15 mg/kg/d, he improved rapidly. A biopsy (after 2 weeks on CDCA), showed a giant cell hepatitis, an evolving micronodular cirrhosis, and steatosis. The improvement in liver function on CDCA was associated with a drop in the plasma concentrations and urinary excretions of the 3ß-hydroxy-Δ5 bile acids which are considered hepatotoxic. At age 5 years (on CDCA, 6 mg/kg/d), he was thriving with normal liver function. Neurological development was normal apart from a tendency to trip. Examination revealed pes cavus but no upper motor neuron signs. The findings in this case suggest that CDCA can reduce the activity of cholesterol 27-hydroxylase - the first step in the acidic pathway for bile acid synthesis.

Delayed presentation of a caecal haematoma initially managed as appendicitis.

A 15-year-old boy with caecal haematoma required a right hemicolectomy due to development of small bowel obstruction and near caecal perforation having presented several days after an episode of minor trauma. The position of the caecum between intraperitoneal and extraperitoneal bowel requires special treatment considerations. This is a unique case in an adolescent because caecal haematoma usually presents acutely with abdominal pain.

Nerve hyperplasia: a unique feature of ketamine cystitis.

BACKGROUND: There is an emerging association between ketamine abuse and the development of urological symptoms including dysuria, frequency and urgency, which have a neurological component. In addition, extreme cases are associated with severe unresolving bladder pain in conjunction with a thickened, contracted bladder and an ulcerated/absent urothelium. Here we report on unusual neuropathological features seen by immunohistology in ketamine cystitis. RESULTS: In all cases, the lamina propria was replete with fine neurofilament protein (NFP+) nerve fibres and in most patients (20/21), there was prominent peripheral nerve fascicle hyperplasia that showed particular resemblance to Morton's neuroma. The nerve fascicles, which were positive for NFP, S100 and the p75 low-affinity nerve growth factor receptor (NGFR), were generally associated with a well-developed and in places, prominent, epithelial membrane antigen+/NGFR+ perineurium. This peripheral nerve fascicle hyperplasia is likely to account for the extreme pain experienced by ketamine cystitis patients. Urothelial damage was a notable feature of all ketamine cystitis specimens and where urothelium remained, increased NGFR expression was observed, with expansion from a basal-restricted normal pattern of expression into the suprabasal urothelium. CONCLUSIONS: The histological findings were distinguishing features of ketamine cystitis and were not present in other painful bladder conditions. Ketamine cystitis afflicts predominantly young patients, with unknown long-term consequences, and requires a strategy to control severe bladder pain in order to remove a dependency on the causative agent. Our study indicates that the development of pain in ketamine cystitis is mediated through a specific neurogenic mechanism that may also implicate the urothelium.

Urinary schistosomiasis in children in the United Kingdom.

We report on two patients with urinary schistosomiasis, who both presented within a fortnight to our hospital with similar symptoms of persistent painless haematuria. Ultrasound, cystoscopic biopsies and histology were used to confirm diagnosis. Treatment with praziquantel was given. Symptoms of urinary schistosomiasis can easily be missed in non-endemic areas and possibly confused with a more sinister pathology. A thorough history and awareness of disease can avoid interventional investigations.

Bile acid-CoA ligase deficiency--a new inborn error of bile acid metabolism.

Born at 27 weeks gestation, a child of consanguineous parents of Pakistani origin required prolonged parenteral nutrition. She developed jaundice, with extensive fibrosis and architectural distortion at liver biopsy; jaundice resolved with supportive care. Serum γ-glutamyl transpeptidase values were within normal ranges. The bile acids in her plasma and urine were >85% unconjugated (non-amidated). Two genes encoding bile-acid amidation enzymes were sequenced. No mutations were found in BAAT, encoding bile acid-CoA : aminoacid N-acyl transferase. The patient was homozygous for the missense mutation c.1012C > T in SLC27A5, predicted to alter a highly conserved amino-acid residue (p.H338Y) in bile acid-CoA ligase (BACL). She also was homozygous for the missense mutation c.1772A > G in ABCB11, predicted to alter a highly conserved amino-acid residue (p.N591S) in bile salt export pump (BSEP). BACL is essential for reconjugation of bile acids deconjugated by gut bacteria, and BSEP is essential for hepatocyte-canaliculus export of conjugated bile acids. A female sibling born at term had the same bile-acid phenotype and SLC27A5 genotype, without clinical liver disease. She was heterozygous for the c.1772A > G ABCB11 mutation. This is the first report of a mutation in SLC27A5. The amidation defect may have contributed to cholestatic liver disease in the setting of prematurity, parenteral nutrition, and homozygosity for an ABCB11 mutation.

Tissue engineering potential of urothelial cells from diseased bladders.

PURPOSE: We examined the suitability of urothelium from patients with abnormal bladders for use in surgical reconstruction using a tissue engineering approach that would require autologous urothelium to be expanded by propagation in cell culture. MATERIALS AND METHODS: Resection specimens from 8 children (median age 9.8 years) with abnormal bladders (neuropathic in 4, posterior urethral valves in 2, epispadias in 1, nonneurogenic in 1) were collected with informed parental consent during planned urological procedures. Six patients had recurrent urinary tract infections and 7 underwent frequent intermittent catheterization. A representative sample was immunohistologically processed to assess urothelial proliferation and differentiation status, and the remaining 7 cases were processed for urothelial cell culture. Five normal adult urothelial samples were included as controls. RESULTS: Immunohistological assessment indicated that 3 of 8 samples lacked urothelial differentiation associated expression of UPK3a or CK20. Four of 7 samples resulted in successful primary culture, with 1 sample lost to underlying infection and 2 not surviving in culture. All 4 cultures grew beyond passage 3 before senescence but all showed reduced proliferation capacity and a compromised ability to form a barrier urothelium compared to controls. CONCLUSIONS: While normal human urothelium is highly regenerative and derived cells are highly proliferative in culture, our results with urothelium from abnormal pediatric bladders indicate a reduced capacity for proliferation and differentiation in vitro. This finding may indicate a need to identify alternative cell sources for engineered bladder reconstruction.

Multicystic dysplastic kidney disease and hypertension: clinical and pathological correlation.

We report on a child with hypertension secondary to MCDK who underwent an elective retroperitoneoscopic nephrectomy and is normotensive on follow up. We looked at the pathological correlation with respect to the hypertension caused by a non-functioning kidney.

Value of mismatch repair, KRAS, and BRAF mutations in predicting recurrence and benefits from chemotherapy in colorectal cancer.

PURPOSE: It is uncertain whether modest benefits from adjuvant chemotherapy in stage II colorectal cancer justify the toxicity, cost, and inconvenience. We investigated the usefulness of defective mismatch repair (dMMR), BRAF, and KRAS mutations in predicting tumor recurrence and sensitivity to chemotherapy. PATIENTS AND METHODS: Immunohistochemistry for dMMR and pyrosequencing for KRAS/BRAF were performed for 1,913 patients randomly assigned between fluorouracil and folinic acid chemotherapy and no chemotherapy in the Quick and Simple and Reliable (QUASAR) trial. RESULTS: Twenty-six percent of 695 right-sided colon, 3% of 685 left-sided colon, and 1% of 407 rectal tumors were dMMR. Similarly, 17% of right colon, 2% of left colon, and 2% of rectal tumors were BRAF mutant. KRAS mutant tumors were more evenly distributed: 40% right colon, 28% left colon, and 36% rectal tumors. Recurrence rate for dMMR tumors was half that for MMR-proficient tumors (11% [25 of 218] v 26% [438 of 1,695] recurred; risk ratio [RR], 0.53; 95% CI, 0.40 to 0.70; P < .001). Risk of recurrence was also significantly higher for KRAS mutant than KRAS wild-type tumors (28% [150 of 542] v 21% [219 of 1,041]; RR, 1.40; 95% CI, 1.12 to 1.74; P = .002) but did not differ significantly between BRAF mutant and wild-type tumors (P = .36). No marker predicted benefit from chemotherapy with efficacy not differing significantly by MMR, KRAS, or BRAF status. The prognostic value of MMR and KRAS was similar in the presence and absence of chemotherapy. CONCLUSION: MMR assays identify patients with a low risk of recurrence. KRAS mutational analysis provides useful additional risk stratification to guide use of chemotherapy.

Cellular integration and vascularisation promoted by a resorbable, particulate-leached, cross-linked poly(ε-caprolactone) scaffold.

Flexible, strong scaffolds were created by crosslinking PCL with 1,6-hexamethylenediisocyanate, using paraffin beads as a porogen. Particulate leaching generated homogeneous scaffolds with interconnected spherical pores of 5-200 µm. Subcutaneous implantation in rats for 3 months resulted in minimal scaffold resorption and a non-inflammatory regenerative host response, with complete infiltration by alternatively-activated CD68(+) macrophages. In addition, scaffolds were populated extensively along microfractures by a stromal matrix, which was highly vascularised and contained a subset of stromal cells that expressed the anti-inflammatory CD163 antigen. Such microfractures may be an important physical feature for directing stromal integration and vascularisation events.

Transplantation of autologous differentiated urothelium in an experimental model of composite cystoplasty.

BACKGROUND: Enterocystoplasty is associated with serious complications resulting from the chronic interaction between intestinal epithelium and urine. Composite cystoplasty is proposed as a means of overcoming these complications by substituting intestinal epithelium with tissue-engineered autologous urothelium. OBJECTIVE: To develop a robust surgical procedure for composite cystoplasty and to determine if outcome is improved by transplantation of a differentiated urothelium. DESIGN, SETTING, AND PARTICIPANTS: Bladder augmentation with in vitro-generated autologous tissues was performed in 11 female Large-White hybrid pigs in a well-equipped biomedical centre with operating facilities. Participants were a team comprising scientists, urologists, a veterinary surgeon, and a histopathologist. MEASUREMENTS: Urothelium harvested by open biopsy was expanded in culture and used to develop sheets of nondifferentiated or differentiated urothelium. The sheets were transplanted onto a vascularised, de-epithelialised, seromuscular colonic segment at the time of bladder augmentation. After removal of catheters and balloon at two weeks, voiding behaviour was monitored and animals were sacrificed at 3 months for immunohistology. RESULTS AND LIMITATIONS: Eleven pigs underwent augmentation, but four were lost to complications. Voiding behaviour was normal in the remainder. At autopsy, reconstructed bladders were healthy, lined by confluent urothelium, and showed no fibrosis, mucus, calculi, or colonic regrowth. Urothelial morphology was transitional with variable columnar attributes consistent between native and augmented segments. Bladders reconstructed with differentiated cell sheets had fewer lymphocytes infiltrating the lamina propria, indicating more effective urinary barrier function. CONCLUSIONS: The study endorses the potential for composite cystoplasty by (1) successfully developing reliable techniques for transplanting urothelium onto a prepared, vascularised, smooth muscle segment and (2) creating a functional urothelium-lined augmentation to overcome the complications of conventional enterocystoplasty.

Histologic oddities at the porta hepatis in biliary atresia.

PURPOSE: Highly unusual histologic findings at the porta hepatis in 3 infants who underwent Kasai portoenterostomy for biliary atresia are reported. METHODS: Portoenterostomy was performed using a standard operative technique. Serial transverse sections of the excised portal plate were examined by light microscopy along with sections from the distal extrahepatic biliary remnants, gallbladder, and liver biopsy. RESULTS: Of 61 consecutive infants who underwent Kasai portoenterostomy for biliary atresia, 3 were found to have highly unusual histologic features at the porta hepatis. All had type 3 biliary atresia. Two had hilar biliary ductules lined in part by squamous epithelium, and the third had a focus of mature hyaline cartilage surrounded by perichondrium adjacent to biliary ductules. In each case, these unusual histologic features were localized to the porta hepatis in the region of the transected portal plate. CONCLUSIONS: The presence of hyaline cartilage at the portal plate is likely to be an expression of defective morphogenesis, thus supporting the concept of disordered embryogenesis in the etiology of biliary atresia. Squamous epithelium within biliary ductules might also reflect a similar mechanism but could alternatively be an unusual metaplastic response to inflammation at this site.