Mutational signature, cancer driver genes mutations and transcriptomic subgroups predict hepatoblastoma survival.

BACKGROUND: Hepatoblastoma is the most frequent pediatric liver cancer. The current treatments lead to 80% of survival rate at 5 years. In this study, we evaluated the clinical relevance of molecular features to identify patients at risk of chemoresistance, relapse and death of disease. METHODS: All the clinical data of 86 children with hepatoblastoma were retrospectively collected. Pathological slides were reviewed, tumor DNA sequencing (by whole exome, whole genome or target) and transcriptomic profiling with RNAseq or 300-genes panel were performed. Associations between the clinical, pathological, mutational and transcriptomic data were investigated. RESULTS: High-risk patients represented 44% of our series and the median age at diagnosis was 21.9 months (range: 0-208). Alterations of the WNT/ß-catenin pathway and of the 11p15.5 imprinted locus were identified in 98% and 74% of the tumors, respectively. Other cancer driver genes mutations were only found in less than 11% of tumors. After neoadjuvant chemotherapy, disease-specific survival and poor response to neoadjuvant chemotherapy were associated with 'Liver Progenitor' (p = 0.00049, p < 0.0001) and 'Immune Cold' (p = 0.0011, p < 0.0001) transcriptomic tumor subtypes, SBS35 cisplatin mutational signature (p = 0.018, p = 0.001), mutations in rare cancer driver genes (p = 0.0039, p = 0.0017) and embryonal predominant histological type (p = 0.0013, p = 0.0077), respectively. Integration of the clinical and molecular features revealed a cluster of molecular markers associated with resistance to chemotherapy and survival, enlightening transcriptomic 'Immune Cold' and Liver Progenitor' as a predictor of survival independent of the clinical features. CONCLUSIONS: Response to neoadjuvant chemotherapy and survival in children treated for hepatoblastoma are associated with genomic and pathological features independently of the clinical features.

Adverse Events and Morbidity in a Multidisciplinary Pediatric Robotic Surgery Program. A prospective, Observational Study.

OBJECTIVE: To report one-year morbidity of robotic-assisted laparoscopic surgery (RALS) in a dedicated, multidisciplinary, pediatric robotic surgery program. Summary Background Data. RALS in pediatric surgery is expanding, but data on morbidity in children is limited. METHODS: All children who underwent RALS (Da Vinci Xi, Intuitive Surgical, USA) were prospectively included (October 2016 to May 2020; follow-up ≥1 year). Analyzed data: patient characteristics, surgical indication/procedure, intraoperative adverse events (ClassIntra classification), blood transfusion, hospital stay, postoperative complications (Clavien-Dindo). RESULTS: Three hundred consecutive surgeries were included: urology/gynecology (n=105), digestive surgery (n=83), oncology (n=66), ENT surgery (n=28), thoracic surgery (n=18). Median age and weight at surgery were 9.5 [interquartile range (IQR)=8.8] years and 31 [IQR=29.3] kg, respectively. Over one year, 65 (22%) children presented with ≥1 complication, with Clavien-Dindo ≥III in 14/300 (5%) children at ≤30 days, 7/300 (2%) at 30-90 days, and 12/300 (4%) at >90 days. Perioperative transfusion was necessary in 15 (5%) children, mostly oncological (n=8). Eight (3%) robotic malfunctions were noted, one leading to conversion (laparotomy). Overall conversion rate was 4%. ASA ≥3, weight ≤15 kg, and surgical oncology did not significantly increase the conversion rate, complications, or intraoperative adverse events (ClassIntra ≥2). ASA score was significantly higher in children with complications (Clavien-Dindo ≥III) than without (p=0.01). Median hospital stay was 2 [IQR=3] days. Three children died after a median follow-up of 20 [IQR=16] months. CONCLUSIONS: RALS is safe, even in the most vulnerable children with a wide scope of indications, age, and weight. Robot-specific complications or malfunctions are scarce.

Antithrombin supplementation for prevention of vascular thrombosis after pediatric liver transplantation.

AIMS: After liver transplantation (LT), synthesis of coagulation factors by the graft recovers faster for pro thrombotic than anti thrombotic factors, resulting in a potential pro thrombotic imbalance. We studied the thrombotic and hemorrhagic complications in our pediatric LT series, providing supplementation of fresh frozen plasma (FFP) and/or antithrombin (AT) in the prophylactic antithrombotic regimen. METHODS: This was a retrospective observational single center study. All isolated pediatric LTs performed between 1/11/2009 and 31/12/2019 (n = 181) were included. Postoperatively, in addition to low molecular weight heparin, 22 patients (12%) received FFP (10 ml/kg twice daily for 10 days), 27 patients (15%) were given FFP (reduced duration) and AT (50-100 IU/kg/day if AT activity remained <70%), and 132 (73%) received AT only. Complications, outcome, and coagulation profiles in postoperative days 0-10 were analyzed. RESULTS: In all three treatment groups, AT activity normalized by day 4 while prothrombin remained <70% of normal until day 9. Hepatic artery thrombosis (HAT), portal vein thrombosis (PVT), and hemorrhagic complications occurred in 2.8%, 3.3%, and 3.9% of LTs. One- and 5-year patient and graft survival were 88% (±2.4% Standard Error) and 84% (±2.5%), and 86% (±2.6%) and 84% (±2.7%), respectively, without difference between groups. HAT were associated with low AT on days 0 and 1, and PVT with low AT on day 0. CONCLUSIONS: Low antithrombin activity after LT was associated with postoperative thromboses. FFP and/or AT supplementation allowed early normalization of AT activity, while thrombotic or hemorrhagic complications were rare, suggesting efficient and safe management of post-LT coagulopathy.

Outcome of Total Colonic Aganglionosis Involving the Small Bowel Depends on Bowel Length, Liver Disease, and Enterocolitis.

OBJECTIVES: Total colonic aganglionosis involving the small bowel is a rare form of Hirschsprung disease. We aim to analyse the long-term outcomes, digestive autonomy, and complications, to suggest recommendations for prevention and treatment. METHODS: All patients born between 2000 and 2015 followed in our centre were retrospectively included. We analysed the length of aganglionosis, surgical procedures, growth, duration of parenteral nutrition (PN), enterocolitis, liver disease, intestinal transplantation. RESULTS: Twenty-five patients were followed for a median of 10.9 years. Fifteen patients had less than 80 cm of ganglionic small bowel (SB) with a median of 20 cm. Ten patients had more than 80 cm of ganglionic sB with a median of 115 cm. The median PN duration was significantly shorter for patients with more than 80 cm: 0.9 versus 7.5 years in those with less than 80 cm (P  < 0.001). No patient with less than 80 cm was weaned off PN, except 1 who underwent intestinal transplantation. Ten patients with less than 80 cm develop enterocolitis on the excluded segment, leading to emergency entero-colectomy in 5. Liver disease was more frequent in patients with less than 80 cm (11 vs 0). Three patients required combined liver-intestine transplantation; 2 underwent an isolated intestinal transplantation. CONCLUSIONS: Digestive autonomy was possible in most patients with more than 80 cm of ganglionic SB. The more severe complication was enterocolitis. Liver disease compromised long-term survival without transplantation. Both complications should be prevented by early diversion and enterectomy of the whole aganglionic segment. Follow-up in or together with a multidisciplinary intestinal rehabilitation centre is suggested.

Robotic Surgery in Pediatric Oncology: Lessons Learned from the First 100 Tumors-A Nationwide Experience.

BACKGROUND: While robotics has become commonplace in adult oncology, it remains rare in pediatric oncology due to the rarity of childhood cancers. We present the results of a large nationwide experience with robotic oncology, with the aim of providing practical and feasible guidelines for child selection. METHODS: This was a prospective analysis performed over a period of 4 years. Treatment was delivered according to the Société Internationale d'Oncologie Pédiatrique/International Society of Paediatric Oncology Europe Neuroblastoma Group (SIOP/SIOPEN) protocols. Indications were approved by a certified tumor board. RESULTS: Overall, 100 tumors were resected during 93 procedures (abdomen, 67%; thorax, 17%; pelvis, 10%; retroperitoneum, 6%) in 89 children (56 girls). The median age at surgery was 8.2 years (range 3.6-13); 19 children (21%) harbored germinal genetic alterations predisposing to cancer. No intraoperative tumor ruptures occurred. Seven conversions (8%) to an open approach were performed. Neuroblastic tumors (n = 31) comprised the main group (18 neuroblastomas, 4 ganglioneuroblastomas, 9 ganglioneuromas) and renal tumors comprised the second largest group (n = 24, including 20 Wilms' tumors). The remaining 45 tumors included neuroendocrine (n = 12), adrenal (n = 9), germ-cell (n = 7), pancreatic (n = 4), thymic (n = 4), inflammatory myofibroblastic (n = 4), and different rare tumors (n = 5). Overall, 51 tumors were malignant, 2 were borderline, and 47 were benign. The median hospital stay was 3 days (2-4), and five postoperative complications occurred within the first 30 days. During a median follow-up of 2.4 years, one child (Wilms' tumor) presented with pleural recurrence. One girl with Wilms' tumor died of central nervous system metastasis. CONCLUSIONS: Robotic surgery for pediatric tumors is a safe option in highly selected cases. Indications should be discussed by tumor boards to avoid widespread and uncontrolled application.

Preservation of native sigmoid colon for secondary continent cystostomy after multivisceral transplantation for chronic intestinal pseudo-obstruction.

Chronic intestinal pseudo-obstruction (CIPO) is characterized by severe digestive +/- urinary dysmotility. If the conservative management fails, multivisceral transplantation (MVT) may be needed. However, urinary dysmotility remains after MVT and requires to continue urinary catheterizations and/or drainage. We report on a boy with severe CIPO complicated by (1) chronic intestinal obstruction requiring total parenteral nutrition, decompression gastrostomy, and ileostomy; (2) recurrent line infections; (3) hepatic fibrosis; and (4) distension of the bladder and upper urinary tract, and recurrent urinary infections, leading to non-continent cystostomy for urinary drainage. He underwent MVT at the age of 5 years. The transplant included the liver, stomach, duodenum and pancreas, small bowel, and right colon. The distal native sigmoid colon was preserved. Fifteen months later, he underwent a pull through of the transplanted right colon (Duhamel's procedure), together with a tube continent cystostomy (Monti's procedure) using the native sigmoid. Postoperative course was uneventful, and the remaining ileostomy was closed 3 months later. Five years post-transplant, he is alive and well. He is fed by mouth with complementary gastrostomy feeding at night. He has 3-6 stools per day, with occasional soiling. The cystostomy is used for intermittent urinary catheterization 4 times/day and continuous drainage at night. He is dry, with rare afebrile urinary infections, normal renal function, and un-dilated upper urinary tract. Conclusion: in severe CIPO with urinary involvement, preservation of the distal native sigmoid colon during MVT allows secondary creation of a continent tube cystostomy, which is useful to manage persistent urinary disease.

Population pharmacokinetics of intravenous and oral ciprofloxacin in children to optimize dosing regimens.

PURPOSE: This study aimed to characterize pharmacokinetics of intravenous and oral ciprofloxacin in children to optimize dosing scheme. METHODS: Children treated with ciprofloxacin were included. Pharmacokinetics were described using non-linear mixed-effect modelling and validated with an external dataset. Monte Carlo simulations investigated dosing regimens to achieve a target AUC0-24 h/MIC ratio ≥ 125. RESULTS: A total of 189 children (492 concentrations) were included. A two-compartment model with first-order absorption and elimination best described the data. An allometric model was used to describe bodyweight (BW) influence, and effects of estimated glomerular filtration rate (eGFR) and age were significant on ciprofloxacin clearance. CONCLUSION: The recommended IV dose of 10 mg/kg q8h, not exceeding 400 mg q8h, would achieve AUC0-24 h to successfully treat bacteria with MICs ≤ 0.25 (e.g. Salmonella, Escherichia coli, Proteus, Haemophilus, Enterobacter, and Klebsiella). A dose increase to 600 mg q8h in children > 40 kg and to 15 mg/kg q8h (max 400 mg q8h, max 600 mg q8h if augmented renal clearance, i.e., eGFR > 200 mL/min/1.73 m2) in children < 40 kg would be needed for the strains with highest MIC (16% of Pseudomonas aeruginosa and 47% of Staphylococcus aureus). The oral recommended dose of 20 mg/kg q12h (not exceeding 750 mg) would cover bacteria with MICs ≤ 0.125 but may be insufficient for bacteria with higher MIC and a dose increase according bodyweight and eGFR would be needed. These doses should be prospectively confirmed, and a therapeutic drug monitoring could be used to refine them individually.

Biliary and duodenal complications after « en bloc¼ liver-small bowel transplantation in children. A single center cohort study.

BACKGROUND: The technique of « en bloc¼ liver and small bowel transplantation (L-BT) spares a biliary anastomosis, but does not protect against biliary complications. We analyze biliary and duodenal complications (BDC) in our pediatric series. METHODS: Between 1994 and 2020, 54 L-BT were performed in 53 children. The procurement technique included in situ vascular dissection and pancreatic reduction to the head until 2009 (group A). Thereafter, the whole pancreas was recovered (group B). RESULTS: Nine BDCs occurred in 8/53 (15%) patients (7 in group A and 1 in group B): leak of the donor's duodenal stump (2), stenosis of the extra-pancreatic bile duct (5), and intra-pancreatic bile duct stenosis (2). Median delay for diagnosis of stricture was 8 months (4-168). Interventional radiology was successful in one child only, the others required reoperations. Two patients died, of biliary cirrhosis or cholangitis, 15-month and 12-year post-L-BT. One was listed and liver re-transplanted 13 years post-L-BT. At last follow-up, two patients only had normal liver tests and ultrasound. CONCLUSION: BDC after L-BT can cause severe morbidities. Pancreatic reduction might increase this risk. Early surgical complications or chronic pancreatic rejection might be co-factors. Early diagnosis and treatment are key to the long-term prognosis.

Peritoneovenous Shunt for Intractable Ascites in Children: A Series of 4 Cases.

ABSTRACT: Intractable ascites is a rare condition in children mainly caused by cirrhosis or lymphatic disorders. Internal drainage may be considered as rescue therapy. In our department, 4 patients ages from 2 months to 15 years old underwent a peritoneovenous shunt (PVS) placement between 2010 and 2020. The surgically inserted device was a pumping device that enabled to drain ascites from the peritoneum into the venous system via the internal jugular vein (Denver shunt, BD Company, NJ). Immediate efficient drainage was achieved in all cases and lasted up to 9 years. Two major complications occurred: a postoperative fat embolism requiring urgent temporary ligation of the shunt and endocarditis shortly after inguinal hernia repair performed 16 months after placement of the shunt. Implementation of a PVS may be a useful procedure in patients with refractory ascites. Chylous ascites should be drained and washed totally before activating the device to avoid fat embolism. Antibiotic prophylaxis is required when abdominal surgery is planned while the device is in place.

Arterial abnormalities identified in kidneys transplanted into children during the COVID-19 pandemic.

Graft artery stenosis can have a significant short- and long-term negative impact on renal graft function. From the beginning of the COVID-19 pandemic, we noticed an unusual number of graft arterial anomalies following kidney transplant (KTx) in children. Nine children received a KTx at our center between February and July 2020, eight boys and one girl, of median age of 10 years. Seven presented Doppler features suggesting arterial stenosis, with an unusual extensive pattern. For comparison, over the previous 5-year period, persistent spectral Doppler arterial anomalies (focal anastomotic stenoses) following KTx were seen in 5% of children at our center. We retrospectively evidenced severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in five of seven children with arterial stenosis. The remaining two patients had received a graft from a deceased adolescent donor with a positive serology at D0. These data led us to suspect immune postviral graft vasculitis, triggered by SARS-CoV-2. Because the diagnosis of COVID-19 is challenging in children, we recommend pretransplant monitoring of graft recipients and their parents by monthly RT-PCR and serology. We suggest balancing the risk of postviral graft vasculitis against the risk of prolonged dialysis when considering transplantation in a child during the pandemic.

Analysis of enteric nervous system and intestinal epithelial barrier to predict complications in Hirschsprung's disease.

In Hirschsprung's disease (HSCR), postoperative course remains unpredictable. Our aim was to define predictive factors of the main postoperative complications: obstructive symptoms (OS) and Hirschsprung-associated enterocolitis (HAEC). In this prospective multicentre cohort study, samples of resected bowel were collected at time of surgery in 18 neonates with short-segment HSCR in tertiary care hospitals. OS and HAEC were noted during postoperative follow-up. We assessed the enteric nervous system and the intestinal epithelial barrier (IEB) in ganglionic segments by combining immunohistochemical, proteomic and transcriptomic approaches, with functional ex vivo analysis of motility and para/transcellular permeability. Ten HSCR patients presented postoperative complications (median follow-up 23.5 months): 6 OS, 4 HAEC (2 with OS), 2 diarrhoea (without OS/HAEC). Immunohistochemical analysis showed a significant 41% and 60% decrease in median number of nNOS-IR myenteric neurons per ganglion in HSCR with OS as compared to HSCR with HAEC/diarrhoea (without OS) and HSCR without complications (p = 0.0095; p = 0.002, respectively). Paracellular and transcellular permeability was significantly increased in HSCR with HAEC as compared to HSCR with OS/diarrhoea without HAEC (p = 0.016; p = 0.009) and HSCR without complications (p = 0.029; p = 0.017). This pilot study supports the hypothesis that modulating neuronal phenotype and enhancing IEB permeability may treat or prevent postoperative complications in HSCR.

Early Bacterial Infections After Pediatric Liver Transplantation in the Era of Multidrug-resistant Bacteria: Nine-year Single-center Retrospective Experience.

BACKGROUND: Early bacterial infection is a major and severe complication after liver transplantation (LT). The rise of antimicrobial resistance, especially extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE), is a growing concern for these patients. This study aimed to assess the epidemiology of early bacterial infections in a pediatric population, including those caused by multidrug-resistant (MDR) pathogens, and to identify risk factors for infection. METHODS: We conducted a monocentric retrospective study including 142 consecutive LTs performed in 137 children between 2009 and 2017. RESULTS: Ninety-three bacterial infections occurred after 67 (47%) LTs. Among the 82 isolated pathogens, the most common was Klebsiella pneumoniae (n = 19, 23%). Independent risk factors for early bacterial infection were low weight [odds ratio (OR) = 0.96; 95% confidence interval (CI): 0.9-0.99; P = 0.03] and the presence of a prosthetic mesh (OR = 2.4; 95% CI: 1.1-5.4; P = 0.046). Sixty-one children (45%) carried MDR bacteria and 16 infections were caused by MDR pathogens, especially ESBL-producing K. pneumoniae (n = 12). ESBL-PE stool carriage was associated with ESBL-PE infection (OR = 4.5; 95% CI: 1.4-17.4; P = 0.02). Four children died from an infection, three due to ESBL-producing K. pneumoniae. CONCLUSIONS: This study confirmed a shift toward a predominance of Gram-negative early bacterial infections after pediatric LT. The risk factors for infection were low weight and the presence of a prosthetic mesh. ESBL-PE stool carriage was associated with ESBL-PE infection. Adapted antimicrobial prophylaxis and personalized antibiotherapy are mandatory to reduce infection prevalence and mortality.

Human IgA binds a diverse array of commensal bacteria.

In humans, several grams of IgA are secreted every day in the intestinal lumen. While only one IgA isotype exists in mice, humans secrete IgA1 and IgA2, whose respective relations with the microbiota remain elusive. We compared the binding patterns of both polyclonal IgA subclasses to commensals and glycan arrays and determined the reactivity profile of native human monoclonal IgA antibodies. While most commensals are dually targeted by IgA1 and IgA2 in the small intestine, IgA1+IgA2+ and IgA1-IgA2+ bacteria coexist in the colon lumen, where Bacteroidetes is preferentially targeted by IgA2. We also observed that galactose-α terminated glycans are almost exclusively recognized by IgA2. Although bearing signs of affinity maturation, gut-derived IgA monoclonal antibodies are cross-reactive in the sense that they bind to multiple bacterial targets. Private anticarbohydrate-binding patterns, observed at clonal level as well, could explain these apparently opposing features of IgA, being at the same time cross-reactive and selective in its interactions with the microbiota.

Long-term outcome of methylmalonic aciduria after kidney, liver, or combined liver-kidney transplantation: The French experience.

Organ transplantation is discussed in methylmalonic aciduria (MMA) for renal failure, and poor quality of life and neurological outcome. We retrospectively evaluated 23 French MMA patients after kidney (KT), liver-kidney (LKT), and liver transplantation (LT). Two patients died, one after LKT, one of hepatoblastoma after KT. One graft was lost early after KT. Of 18 evaluable patients, 12 previously on dialysis, 8 underwent KT (mean 12.5 years), 8 LKT (mean 7 years), and 2 LT (7 and 2.5 years). At a median follow-up of 7.3 (KT), 2.3 (LKT), and 1.0 years (LT), no metabolic decompensation occurred except in 1 KT. Plasma and urine MMA levels dramatically decreased, more after LKT. Protein intake was increased more significantly after LKT than KT. Enteral nutrition was stopped in 7/8 LKT, 1/8 KT. Early complications were frequent after LKT. Neurological disorders occurred in four LKT, reversible in one. Five years after KT, four patients had renal failure. The metabolic outcomes were much better after LKT than KT. LKT in MMA is difficult but improves the quality of life. KT will be rarely indicated. We need more long-term data to indicate early LT, in the hope to delay renal failure and prevent neurodevelopmental complications.

Management of Biliary Atresia in France 1986 to 2015: Long-term Results.

OBJECTIVES: This study analyses the prognosis of biliary atresia (BA) in France since 1986, when both Kasai operation (KOp) and liver transplantation (LT) became widely available. METHODS: The charts of all patients diagnosed with BA born between 1986 and 2015 and living in France were reviewed. RESULTS: A total of 1428 patients were included; 1340 (94%) underwent KOp. Total clearance of jaundice (total bilirubin ≤20 µmol/L) was documented in 516 patients (39%). Age at KOp (median 59 days, range 6-199) was stable over time. Survival with native liver after KOp was 41%, 35%, 26%, and 22% at 5, 10, 20, and 30 years, stable in the 4 cohorts. 25-year survival with native liver was 38%, 27%, 22%, and 19% in patients operated in the first, second, third month of life or later, respectively (P = 0.0001). Center caseloads had a significant impact on results in the 1986 to 1996 cohort only. 16%, 7%, 7%, and 8% of patients died without LT in the 4 cohorts (P = 0.0001). A total of 753 patients (55%) underwent LT. Patient survival after LT was 79% at 28 years. Five-year patient survival after LT was 76%, 91%, 88%, and 92% in cohorts 1 to 4, respectively (P < 0.0001). Actual BA patient survival (from diagnosis) was 81%. Five-year BA patient survival was 72%, 88%, 87%, and 87% in cohorts 1986 to 1996, 1997 to 2002, 2003 to 2009, and 2010 to 2015, respectively (P < 0.0001). CONCLUSIONS: In France, 87% of patients with BA survive nowadays and 22% reach the age of 30 years without transplantation. Improvement of BA prognosis is mainly due to reduced mortality before LT and better outcomes after LT.

Long term outcomes of intestinal rehabilitation in children with neonatal very short bowel syndrome: Parenteral nutrition or intestinal transplantation.

BACKGROUND & AIMS: Intestinal rehabilitation is the preferred treatment for children with short bowel syndrome (SBS) whatever the residual bowel length, and depends on the accurate management of long-term parenteral nutrition (PN). If nutritional failure develops, intestinal transplantation (ITx) should be discussed and may be life-saving. This study aimed to evaluate survival, PN dependency and nutritional status in children with neonatal very SBS on PN or after ITx, in order to define indications and timing of both treatments. PATIENTS AND METHODS: This retrospective cross-sectional study enrolled 36 children with very SBS (<40 cm) who entered our intestinal rehabilitation program from 1987 to 2007. RESULTS: All the children on long-term PN (n = 16) survived with a follow-up of 17 years (9-20). Six of them were eventually weaned off PN. Twenty children underwent ITx: eight children died (40%) 29 months (0-127) after Tx. The others 12 patients were weaned off PN 73 days (13-330) after Tx. Follow-up after transplantation was 14 years (6-28). Seven out of 8 (88%) patients with a history of gastroschisis required ITx. Patients who required ITx had longer stoma duration. CONCLUSION: Survival rate of children with very short bowel was excellent if no life-threatening complications requiring transplantation developed. Gastroschisis and delayed ostomy closure are confirmed as risk factor for nutritional failure. Intestinal rehabilitation may allow a total weaning of PN before adulthood. A follow-up by a multidisciplinary team is necessary to avoid PN complications in order to minimize indications for ITx.

Solid pseudopapillary neoplasms of the pancreas do not express major pancreatic markers in pediatric patients.

Solid pseudopapillary neoplasms (SPNs) of the pancreas are classified as "exocrine" pancreatic tumors by the World Health Organization. However, despite numerous studies using immunohistochemistry, electron microscopy, animal models, and molecular biology, the histogenesis of SPN remains unclear. At the same time, our knowledge of human pancreas development has significantly increased. It is now well known that the undifferentiated PDX1+ pancreatic progenitors proliferate and differentiate into endocrine, ductal, and acinar cells, thanks to the expression of numerous transcription factors, which can be used to better characterize pancreatic tumors. In a series of 14 pediatric SPN, we investigated the expression of 4 transcription factors associated with pancreatic development (PDX1, SOX9, PTF1A, and NKX2.2) to obtain new insights into the pathogenesis of SPN. In addition, we tested the expression of different markers of epithelial, endocrine, exocrine, and neural differentiation using both immunohistochemical and immunofluorescence analyses. All tumors displayed the typical histologic features of SPN, with both pseudopapillary and solid patterns. The immunoprofile was characterized by immunoreactivity for ß-catenin (100%), progesterone receptor (100%), cyclin D1 (100%), synaptophysin (65%), and S100 (15%). In all cases, tumor cells were negative for the following markers: PDX1, SOX9, PTF1A, NKX2.2, chromogranin A, glucagon, insulin, somatostatin, ghrelin, pancreatic polypeptide, amylase, GFAP, calretinin, EPCAM, and estrogen receptor α. To conclude, SPNs do not express major transcription factors involved in pancreatic development and differentiation, which does not allow for precise pancreatic lineage of tumor cells. Thus, additional studies are still required to determine the origin of SPN.