Successful endoscopic approach for peripheral neuroblastic tumors in children.

BACKGROUND: Recently, reports of endoscopic approaches for neuroblastoma, ganglioneuroblastoma, and ganglioneuroma (peripheral neuroblastic tumor; PNTs) have been increasing. This study aimed to clarify the indications for endoscopic surgery for PNTs. METHODS: Pediatric patients who underwent endoscopic surgery for PNTs at our institution were included in this study. Image-defined risk factors (IDRFs) were analyzed using preoperative computed tomography (CT). RESULTS: Twenty-four patients underwent endoscopic surgery for PNTs. The diagnoses included neuroblastoma (n = 11), ganglioneuroma (n = 10), and ganglioneuroblastoma (n = 3). Regarding the tumor site, there were 18 cases of adrenal tumors, five cases of mediastinal tumors, and one case of retroperitoneal tumors. Image-defined risk factors were positive in eight cases (contacted with a renal vessel, n = 6; compression of principal bronchi, n = 2). Complete resection was accomplished in 21 cases (14 of 16 IDRF-negative cases and seven of eight IDRF-positive cases). All patients survived without recurrence during the follow-up period. CONCLUSIONS: The CT findings of contact with renal vessels and compression of principal bronchi do not seem to be indicators of incomplete resection. An endoscopic approach to PNTs in pediatric patients is feasible with a good prognosis if patients are selected strictly.

Potential role of stem cells from human exfoliated deciduous teeth in inducing liver regeneration.

BACKGROUND AND AIM: Even with advancement of medical technologies, liver transplantation still faces several major challenges. Hence, other treatment modalities are urgently needed for patients with end-stage liver disease. Stem cells from human exfoliated deciduous teeth (SHED) was discovered to have highly proliferative and pluripotent properties; including differentiation into hepatocyte-like cells. This study aims to investigate the capability of intrasplenic transplanted SHED and SHED-Hep cells in inducing proliferation of stem cells and native hepatocytes in order to accelerate liver regeneration in liver fibrosis mice models. METHODS: Three carbon tetrachloride (CCl4)-injured male mice groups were used in this study. Two of those groups were transplanted with either SHED or SHED-Hep, while the other did not undergo transplantation. One age- and sex- matched healthy mice group was used as control. All specimens were immunohistochemically stained with anti-Ki-67 antibodies and anti-proliferating cell nuclear antigen (PCNA) antibodies before counter stained with hematoxylin-eosin. RESULTS: Anti-Ki-67 antibodies staining: at both 8 and 12 weeks, proliferating activity was predominantly seen on both SHED- and SHED-Hep-transplanted CCl4-injured mice groups, while control and non-transplanted CCl4-injured mice group showed little to no sign of proliferation activity. Anti-PCNA staining: at both 8 and 12 weeks, significant proliferating activity was detected by PCNA staining, mainly on stem cells population area on SHED- and SHED-Hep-treated group. CONCLUSIONS: In conclusion, this study has provided the evidence that transplantation of SHED or SHED-Hep on liver-injured mice induced proliferation of both transplanted stem cells and native liver cells in order to accelerate liver regeneration.

The Effectiveness of Deflux® Treatment for Vesicoureteral Reflux Following Pediatric Renal Transplantation: A Single-Institution Challenging Experience.

PURPOSE: To validate the effectiveness of Deflux® treatment for vesicoureteral reflux (VUR) following pediatric renal transplantation (RT), based on our single-institution experience. METHOD: A retrospective study was conducted using the medical records of pediatric patients who underwent Deflux® treatment for VUR after RT from April 2008 to March 2022. RESULTS: Sixty-eight pediatric patients underwent RT. VUR was subsequently detected in 22 (32 %) of these patients. Seven of the 22 patients (32 %) underwent Deflux® treatment to avoid renal dysfunction due to urinary infection (UTI). The median age at the time of RT was 4 years (range:2-12). All 7 patients had urinary UTIs before Deflux® treatment. The median estimated glomerular filtration rate (eGFR) before Deflux® treatment was 67 ml/min/1.73 m2 (range:42-138 ml/min/1.73 m2). After Deflux® treatment, VUR was downgraded in three cases (43 %). Four patients (57 %) experienced postoperative UTI, two of who underwent a second Deflux® treatment, one underwent submuscular tunnel reconstruction, and the other one experienced UTI without VUR after 1st Deflux® treatment but did not reoccur. All seven patients continued prophylactic medication after Deflux® treatment, without any history of recurrent UTIs during the observation period after treatment (median 37 months [range 7-86 months]). Furthermore, the eGFRs did not significantly decrease after Deflux® treatment (median eGFR 58 ml/min/1.73 m2 [range:33-99 ml/min/1.73 m2], p > 0.1). CONCLUSION: Deflux® treatment for VUR after RT is technically challenging because the new ureteral orifice is ventrally anastomosed at the bladder. We believe our results indicate the possibility of reducing the frequency of UTIs and contributing to preservation of the renal function after RT. TYPE OF STUDY: Retrospective Study. LEVEL OF EVIDENCE: Level III.

The advantages of duct-to-duct biliary reconstruction in pediatric living donor liver transplantation.

BACKGROUND/PURPOSE: Whether Roux-en-Y hepatic jejunectomy (HJ) or duct-to-duct biliary reconstruction (DD) is more useful in pediatric living donor liver transplantation has not yet been fully investigated. Therefore, to assess the feasibility and safety of DD, we compared the surgical outcomes of DD to HJ. METHODS: We divided 45 patients, excluding those with biliary atresia, into the DD group (n = 20) and the HJ group (n = 25), according to the type of biliary reconstruction they received. RESULTS: The 5-year survival rates (DD vs. HJ = 79.7% vs. 83.6%, p = 0.70) and the incidence of biliary complications, including bile leakage and stricture (DD vs. HJ = 1 [5.0%] vs. 1 [4.0%], p = 0.87) were not significantly different between the groups. However, intestinal complications, including bowel perforation or ileus, were significantly common in the HJ group (9/25 [36.0%]) than in the DD group (1/20 [5.0%]; p = 0.01). The three patients in the HJ group with intestinal perforation all suffered perforation at the anastomosed site in the Roux-en-Y procedure. The subgroup analysis showed the non-inferiority of DD to HJ for biliary or intestinal complications in patients weighting < 10 kg. CONCLUSION: With a proper selection of cases, DD should be a safe method for biliary reconstruction in pediatric recipients with little risk of biliary complications equivalent to HJ and a reduced risk of intestinal complications.

Surgical outcome and prognosis of pediatric solid-pseudopapillary neoplasm.

BACKGROUND: The aim of this study was to clarify the characteristics and outcomes of pediatric patients with solid pseudopapillary neoplasms (SPNs) who underwent pancreatectomy. METHODS: Pediatric patients with SPNs who underwent pancreatectomy at our institution between 1995 and 2020 were included in the study. RESULTS: During the period under review, 12 patients underwent pancreatectomy for SPNs (median age: 10 years; range: 6-15 years). The surgical procedures included pancreatoduodenectomy (n = 2; 16.6%), distal pancreatectomy (n = 3; 25%), and enucleation (n = 7; 58.3%). The most common postoperative complication was postoperative pancreatic fistula (n = 6; 50%). Patients who underwent enucleation tended to have higher postoperative complication rates compared with those who underwent other procedures. All patients were alive without recurrence at the end of the study period. CONCLUSIONS: SPN is associated with a good prognosis, regardless of the surgical procedure. If surgeons select enucleation for pediatric SPNs, they should bear in mind that it is associated with a higher complication rate.

Cutting-edge regenerative therapy for Hirschsprung disease and its allied disorders.

Hirschsprung disease (HSCR) and its associated disorders (AD-HSCR) often result in severe hypoperistalsis caused by enteric neuropathy, mesenchymopathy, and myopathy. Notably, HSCR involving the small intestine, isolated hypoganglionosis, chronic idiopathic intestinal pseudo-obstruction, and megacystis-microcolon-intestinal hypoperistalsis syndrome carry a poor prognosis. Ultimately, small-bowel transplantation (SBTx) is necessary for refractory cases, but it is highly invasive and outcomes are less than optimal, despite advances in surgical techniques and management. Thus, regenerative therapy has come to light as a potential form of treatment involving regeneration of the enteric nervous system, mesenchyme, and smooth muscle in affected areas. We review the cutting-edge regenerative therapeutic approaches for managing HSCR and AD-HSCR, including the use of enteric nervous system progenitor cells, embryonic stem cells, induced pluripotent stem cells, and mesenchymal stem cells as cell sources, the recipient intestine's microenvironment, and transplantation methods. Perspectives on the future of these treatments are also discussed.

Present state of intestinal transplantation in Japan.

INTRODUCTION: Intestinal transplantation (ITx) is the ultimate treatment for intestinal failure (IF). In Japan, most cases of IF are a result of pediatric disease, including secondary or congenital intestinal disease or allied disorders of Hirschsprung's disease. Here, we report the results of the Japanese ITx registry. METHODS: A web-based survey form was completed. We investigated the number, age, sex, indication, surgical procedure, immunosuppressants, postoperative course, and the effects of transplantation in patients who underwent cadaveric or living-donor ITx. RESULTS: By the end of 2022, 42 cases of ITx have been performed in 38 patients in Japan. The donor sources included cadavers (29 cases) and living donors (13 cases). The surgical method was isolated ITx (N = 40) and combined liver and ITx (n = 2). Survival rates were 92%, 73%, and 59% at 1 year, 5 years, and 10 years, respectively. Ninety percent of patients completely discontinued parenteral nutrition. Approximately 80% of the patients had a performance status of 1 or less, indicating that the QOL of patients after ITx was extremely good. CONCLUSION: The results of ITx are acceptable to treat IF patients and the QOL after transplantation is also good.

Efficacy and Safety of Teduglutide in Infants and Children With Short Bowel Syndrome Dependent on Parenteral Support.

OBJECTIVES: Our objective was to evaluate the short- and long-term safety and efficacy of teduglutide treatment in infants and children with short bowel syndrome with intestinal failure (SBS-IF). METHODS: Two open-label phase 3 studies and 1 extension study investigated the short- and long-term safety and efficacy of teduglutide (0.05 mg/kg/day) in infants and children with SBS-IF: NCT03571516, 24-week study of infants who were randomized to receive teduglutide or standard of care (SoC); NCT02980666, 24-week study of infants and children who all received teduglutide; and NCT03268811, 24-week extension study of patients who completed NCT02980666 (patients could receive up to 48 weeks of total treatment). RESULTS: Twelve infants and 8 children enrolled in the core studies, and 2 infants and 7 children in the extension study. After 24 weeks of treatment, parenteral support (PS) requirements reduced by ≥20% from baseline for 4 infants (57.1%) and 4 children (66.7%) receiving teduglutide and for 2 infants receiving SoC (50.0%). One infant (50.0%) and 4 children (80.0%) receiving teduglutide maintained the ≥20% reduction in PS at 48 weeks of treatment. Two children receiving teduglutide achieved enteral autonomy, after 12 weeks and 28 weeks of treatment, respectively. All adverse events (AEs) were in line with known impacts of SBS-IF and adverse reactions to teduglutide. Only one serious AE (abdominal pain) was considered related to teduglutide. CONCLUSIONS: Short- and long-term treatment with teduglutide resulted in clinically meaningful reductions in PS requirements for infants and children with SBS-IF. Teduglutide was well tolerated, and efficacy improved with longer-term treatment.

The Volume of Intestinal Decompression can Predict the Necessity of Surgical Intervention for Adhesive Small Bowel Obstruction.

BACKGROUND: There is no standard timing for switching to surgical management for children with adhesive small bowel obstruction (ASBO) who initially receive conservative treatment. We hypothesized that an increased gastrointestinal drainage volume may indicate the need for surgical intervention. METHODS: The study population included 150 episodes in the patients less than 20 years of age who received treatment for ASBO in our department from January 2008 to August 2019. Patients were divided into two groups: the successful conservative treatment group (CT) and the eventual surgical treatment group (ST). Following the analysis of all episodes (Study 1), we limited our analysis to only first ASBO episodes (Study 2). We retrospectively reviewed their medical records. RESULTS: There were statistically significant differences in the volume on the 2nd day in both Study 1 (9.1 ml/kg vs. 18.7 ml/kg; p < 0.01) and study 2 (8.1 ml/kg vs. 19.7 ml/kg; p < 0.01). The cut-off value was the same for both Study 1 and Study 2 (11.7 ml/kg). CONCLUSIONS: The gastrointestinal drainage volume on the 2nd day in ST was significantly larger than that in CT. Accordingly, we considered that the drainage volume may predict eventual surgical intervention for children with ASBO who initially receive conservative treatment. LEVEL OF EVIDENCE: Level IV.

COVID19 detection in appendix of acute appendicitis in a child: a case report and review of literature.

BACKGROUND: Gastrointestinal symptoms are one of the most common presentations of Coronavirus disease-19 (COVID-19), even in children. Higher rates of complicated appendicitis have been demonstrated in the era of the COVID-19 outbreak, and it has been recently suggested that acute appendicitis may occur as a complication of COVID-19. However, the relationship between appendicitis and COVID-19 remains unclear. CASE PRESENTATION: A 7-year-old male presented to the pediatric emergency department with 2 days' history of lower abdominal discomfort and tenderness. On examination, his abdomen was distended with diffuse mild tenderness at the lower abdomen, which was aggravated by movement. He was also tested and was found to be positive for SARS-CoV-2. Computed tomography showed perforated appendicitis with a fecalith. The patient was admitted and laparoscopic appendectomy was successfully performed. Postoperatively, a minor intra-abdominal abscess was present, which successfully treated with antibiotics. Histopathology showed a markedly inflamed appendix with mucosal ulceration and transmural neutrophilic inflammation, which was consistent with phlegmonous appendicitis. Reverse transcription quantitative polymerase chain reaction using a surgically extracted appendix specimen revealed the presence of SARS-CoV-2 virus, which indicated a pathophysiological relationship between appendicitis and COVID-19. CONCLUSION: The present case will provide further understanding of pediatric patients with concomitant COVID-19 and acute appendicitis.

The Factors Associated with the Selection of Early Excision Surgery for Congenital Biliary Dilatation with a Prenatal Diagnosis.

PURPOSE: The aim of this study was to clarify the appropriate management after birth for congenital biliary dilatation (CBD, choledochal cyst) patients with a prenatal diagnosis. METHOD: Thirteen patients with a prenatal diagnosis of CBD who underwent liver biopsy during excision surgery were divided into two groups and retrospectively analyzed: group A, with liver fibrosis above F1 and group B, without liver fibrosis. RESULTS: Excision surgery was performed earlier in group A (F1-F2), at a median of 106 days old (p = 0.04). There were significant differences between the two groups in the presence symptoms and sludge, the cyst size, and the level of serum bilirubin and gamma glutamyl transpeptidase (GGT) before excision surgery (p < 0.05). Especially, in group A, prolonged serum GGT elevation and larger cysts were consistently observed from birth. The cut-off values of predictions for the presence of liver fibrosis in serum GGT and cyst size were 319 U/l and 45 mm. No significant differences were observed in the postoperative liver function or complications during the follow-up period. CONCLUSION: In patients with prenatally diagnosed CBD, the postnatal serial changes of serum GGT values and cyst size, in addition to symptoms, could help to prevent progressive liver fibrosis. LEVEL OF EVIDENCE: Ⅲ. TYPE OF STUDY: Treatment Study.

Necrotizing enterocolitis associated with food protein-induced enterocolitis syndrome: A case report.

INTRODUCTION: Food protein-induced enterocolitis syndrome (FPIES) is a T-cell-mediated allergy that can occur in newborns and infants who are introduced to milk protein. Some of the serious complications of FPIES include necrotizing enterocolitis (NEC), massive bloody stools, and disseminated intravascular coagulation. Here we report a case of NEC caused by FPIES. PRESENTATION OF CASE: A 28-day-old girl born at full term suddenly developed marked abdominal distention and shock a few hours after being fed highly regulated milk protein. Emergency laparotomy was performed, and extensive small-intestinal necrosis was found. The histological examination showed chronic inflammation with typical ghost crypts, hemorrhage, and extensive pneumatosis intestinalis, a presentation consistent with NEC. DISCUSSION: In this case, the fragile intestinal mucosa associated with FPIES was stimulated by milk protein, leading to NEC. The greatest diagnostic difficulty is the lack of a definitive method for distinguishing between NEC and FPIES. The allergen-specific lymphocyte stimulation test with lactotransferrin was positive, indicating that the primary condition was FPIES. However, no eosinophilic infiltrate was found in the histological examination, but there was chronic inflammation with typical ghost crypts, hemorrhage, and extensive pneumatosis intestinalis. Consequently, the final histological diagnosis in our case was NEC rather than FPIES. CONCLUSION: FPIES has a variable clinical course, and severe FPIES may become exacerbated even after ingestion of highly regulated milk protein. Taking appropriate actions after correct diagnosis can prevent progression to surgical emergency and secondary NEC.

Massive bleeding from a duodenal ulcer in a child with influenza infection: A case report of endoscopic findings.

Gastrointestinal bleeding or perforation following influenza infection is rare. We encountered a pediatric case of hemorrhagic duodenal ulcer following influenza A infection. The patient was a 1-year and 4-month-old boy who was diagnosed with influenza A infection and treated with laninamivir octanoate. After inhalation, he had diarrhea, poor appetite, and melena. The next day, he had hematochezia and developed hemorrhagic shock. Contrast-enhanced computed tomography showed extravasation in the descending part of the duodenum. Esophagogastroduodenoscopy revealed spurting bleeding from a Dieulafoy's lesion on the oral side of the major papilla, and he underwent hemostasis by clipping. From the bulb to the descending part of the duodenum, the mucosa appeared atrophic with spotty redness on the circular folds and multiple and irregularly shaped erosions. Almost all mucosal lesions had healed by the eighth day, and he was monitored as an outpatient for more than one year without re-bleeding. Intestinal ischemia, viral invasion, and drug reaction of laninamivir octanoate may be involved in duodenal mucosal injury. Acute duodenal ulcers may occur in children with influenza infection, especially young children.

Targeting hepatic oxidative stress rescues bone loss in liver fibrosis.

OBJECTIVE: Chronic liver diseases often involve metabolic damage to the skeletal system. The underlying mechanism of bone loss in chronic liver diseases remains unclear, and appropriate therapeutic options, except for orthotopic liver transplantation, have proved insufficient for these patients. This study aimed to investigate the efficacy and mechanism of transplantation of immature hepatocyte-like cells converted from stem cells from human exfoliated deciduous teeth (SHED-Heps) in bone loss of chronic liver fibrosis. METHODS: Mice that were chronically treated with CCl4 received SHED-Heps, and trabecular bone density, reactive oxygen species (ROS), and osteoclast activity were subsequently analyzed in vivo and in vitro. The effects of stanniocalcin 1 (STC1) knockdown in SHED-Heps were also evaluated in chronically CCl4 treated mice. RESULTS: SHED-Hep transplantation (SHED-HepTx) improved trabecular bone loss and liver fibrosis in chronic CCl4-treated mice. SHED-HepTx reduced hepatic ROS production and interleukin 17 (Il-17) expression under chronic CCl4 damage. SHED-HepTx reduced the expression of both Il-17 and tumor necrosis factor receptor superfamily 11A (Tnfrsf11a) and ameliorated the imbalance of osteoclast and osteoblast activities in the bone marrow of CCl4-treated mice. Functional knockdown of STC1 in SHED-Heps attenuated the benefit of SHED-HepTx including anti-bone loss effect by suppressing osteoclast differentiation through TNFSF11-TNFRSF11A signaling and enhancing osteoblast differentiation in the bone marrow, as well as anti-fibrotic and anti-ROS effects in the CCl4-injured livers. CONCLUSIONS: These findings suggest that targeting hepatic ROS provides a novel approach to treat bone loss resulting from chronic liver diseases.

Characteristics of intussusception in the period of arbitrary Rotavirus vaccination.

BACKGROUND: In November 2011, rotavirus (RV) vaccine was launched in Japan as a voluntary vaccination to prevent RV-associated gastroenterocolitis. We examined the characteristics of intussusception following RV vaccination in our two centers. METHODS: We investigated intussusception patients <16 years old from January 2006 to September 2020. Patients were categorized according to the period (before [Group A] or after the introduction of arbitrary RV vaccination [Group B]). The patient characteristics and treatment of intussusception were retrospectively investigated. RESULTS: During the study period, 560 patients (group A, n = 233; group B, n = 327) were identified. The distribution of patients who were 0-6 months old was not significantly different between the groups (group A, n = 12, 5.2%; group B, n = 18, 5.5%). Among these 18 patients in Group B, 7 were vaccinated against RV, and 10 were not. One patient was excluded due to incomplete data. On comparing patients with and without RV vaccination, the mean age at the onset of intussusception was 3.3 ± 0.4 versus 4.0 ± 0.3 months (P = 0.19), the mean interval from the onset to treatment was 7.5 ± 2.4 versus 16.0 ± 2.2 h (P = 0.03), the time of the contrast enema for treatment was 9.1 ± 3.3 versus 7.7 ± 2.8 min (P = 0.76), and the final pressure of the contrast enema was 92.5 ± 4.4 versus 92.2 ± 4.4 cmH2 O (P = 0.97). CONCLUSIONS: Arbitrary RV vaccination did not influence the age distribution of intussusception, and the interval from the onset to treatment was significantly shorter in the patients with RV vaccination than in those without it. Recognizing the presence of intussusception following RV vaccination enables accurate treatment.

Effects of changes in skeletal muscle mass on the prognosis of pediatric malignant solid tumors.

PURPOSE: This study aims to clarify the relationship between changes in skeletal muscle mass during treatment and prognosis of pediatric malignant solid tumors. METHODS: Patients with pediatric malignant solid tumors who were treated at Kyushu University Hospital from 2007 to 2017 were divided into two groups: the progression-free survival (PFS) group and the relapse/death (R/D) group; the psoas major muscle volume (PMV) was then compared. We also measured the PMV and psoas muscle area (PMA) of pediatric patients with no complications who underwent surgery for acute appendicitis (control) and compared the values with those of patients with malignant tumors. RESULTS: No significant differences were observed in the PMV and PMA between patients with appendicitis and those with malignant tumors. Significant differences were found in the rate of change in PMV between the PFS (1.424) and R/D groups (1.071) (P = 0.0024). When the cut-off value of the rate of change in the PMV was 1.20, patients whose rate of change in PMV was ≥ 1.20 had longer PFS (P = 0.0231) and overall survival (P = 0.0229) than those whose rate of change was < 1.20. CONCLUSION: Pediatric patients with malignant solid tumors and increased skeletal muscle mass during treatment have a good prognosis.

Anesthesia management in living-donor liver transplantation in a patient with carbamoyl phosphate synthetase deficiency: a case report.

BACKGROUND: Carbamoyl phosphate synthetase deficiency (CPS1D) is a urea-cycle disorder (UCD). We report successful perioperative management of pediatric living donor liver transplantation (LDLT) in a CPS1D patient. CASE PRESENTATION: A 10-year-old female patient with CPS1D underwent LDLT. Proper administration of dextrose 50% and 60 kcal/kg/day with L-arginine and L-carnitine resulted in the avoidance of intraoperative hyperammonemia induced by hypercatabolism. Serum ammonia level transiently increased to 61 mmol/L in the anhepatic phase and decreased to 44 mmol/L after reperfusion. CONCLUSIONS: We suggest anesthesia management with administration of dextrose to avoid hyperammonemia during LDLT in patients with CPS1D.

"A salvage technique using a fibrous sheath to avoid the loss of the central veins in cases of pediatric intestinal failure".

PURPOSE: The number of accessible central veins (CVs) affects the prognosis of patients with intestinal failure (IF). The loss of residual CVs should be avoided. We, therefore, evaluated the efficacy of a new CV catheter-exchange technique using a subcutaneous fibrous sheath (FS) in pediatric IF patients. METHODS: We retrospectively collected the CV catheter (CVC) data of pediatric IF patients managed from January 2009 to December 2019. The data were divided into two groups; Groups 1 (CVCs placed with the FS method) and Group 2 (CVCs placed by the primary or another insertion). The main outcome was the CVC indwelling time. RESULTS: Eighty-five CVCs were analyzed. The FS method was attempted in 47 cases and succeeded in 40 (85%). No significant difference was observed between the groups regarding characteristics. A log-rank test revealed an equivalent CVC indwelling time between the two groups (Group 1: 268 [126-588] days vs. Group 2: 229 [126-387] days, p = 0.256). CONCLUSIONS: The FS method is highly recommended for pediatric IF patients, as its attempt showed a high success rate with an indwelling time equivalent to primary insertion. The FS method leads to the prolonged use of a single CV and thereby contributes to improving the outcomes of pediatric IF patients.

M-CSFR expression in the embryonal component of hepatoblastoma and cell-to-cell interaction between macrophages and hepatoblastoma.

Tumor-associated macrophages (TAMs) have protumor functions in various cancers. However, their significance in hepatoblastoma, the most common liver tumor in children, remains unclear. The aim of this study was to explore the potential roles of TAMs in hepatoblastoma. Immunohistochemical analysis revealed that the density of CD204-positive TAMs was significantly higher in the embryonal component than in other histological subtypes of hepatoblastoma. An in vitro co-culture study with Huh6 cells and human monocyte-derived macrophages (HMDMs) showed that macrophage-colony-stimulating factor receptor (M-CSFR) was strongly up-regulated in the Huh6 cells that were directly co-cultured with HMDMs. The expressions of M-CSFR ligands (interleukin-34 and M-CSF) were also increased by co-culture with HMDMs. The proliferation of HepG2 cells (another hepatoblastoma cell line expressing M-CSFR) was inhibited by an M-CSFR inhibitor. M-CSFR was found to be highly expressed in the embryonal component and in recurrent lesions. The number of CD204-positive macrophages was also higher in the M-CSFR-positive areas than in the M-CSFR-negative areas. Thus, M-CSFR expression appeared to be induced by cell-cell contact with macrophages in hepatoblastoma cells, and M-CSFR inhibitor is potentially effective against M-CSFR-positive hepatoblastoma, especially recurrent cases.