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Soft tissue sarcomas in neonates are rare and heterogeneous tumors. We report an aggressive neonatal undifferentiated round cell sarcoma with a YWHAE:NUTM2B fusion. The tumor was identified antenatally and the neonate underwent surgical resection at four days of age. Whole-genome and transcriptome sequencing of tumour and germline was undertaken to provide molecular characterization and elucidate possible novel therapies. In addition to molecular characterization of a YWHAE:NUTM2B fusion, RNA expression outliers were described. Targeted therapy was not pursued due to rapid clinical decline. Understanding the genomic profile of rare tumors remains important in the development of novel therapeutic strategies.

Recent anatomical investigations have emphasized the variability in the knee extensor apparatus, with particular attention to a fifth component of the quadriceps femoris termed the tensor vastus intermedius or accessory “quinticeps femoris.” Disorders of this structure have not been described in the pediatric imaging literature. To review the clinical features, pathoanatomy and imaging findings of children presenting with derangement of the accessory quadriceps femoris, with a particular emphasis on the utility of early magnetic resonance imaging (MRI) of the thigh. This is a retrospective analysis of 3 children, ages 3–10 years at presentation, who underwent imaging evaluation with subsequent surgically proven accessory quadriceps femoris muscles. Their clinical histories, including duration of symptoms, MRI findings, intervention and surgical outcomes, are reported. All patients presented with progressive unilateral restricted knee flexion and had multiple imaging studies targeting the knee before diagnosis. Diagnosis in all patients was made on MRI of the thighs, which demonstrated a fusiform low signal intensity structure with muscle-like architecture arising from the anterior or anterolateral proximal femur and blending with the common quadriceps tendon distally. All patients underwent surgical release of the anomalous band with significant functional improvement. In cases of progressive limited knee flexion without intrinsic pathology, an accessory quadriceps muscle should be considered as an extrinsic cause. Our experience demonstrated this to be readily identifiable on MRI, with symptomatic improvement following surgical release. Early recognition of this condition should prevent unnecessary intervention such as knee arthroscopy and the debilitating loss of flexion due to delayed diagnosis.

Applications for bowel US in children have been well described; however, less focus has been placed on patterns of bowel wall architectural change in specific disease states. This pictorial essay reviews normal bowel wall architecture and covers a variety of inflammatory, infectious, vascular and neoplastic disorders outside the neonatal period as seen on US, with illustrative pathological correlation. A thorough understanding of normal and abnormal bowel wall architecture can enrich sonographic interpretation and provide a valuable adjunct to appropriate clinical investigation.

Recent anatomical investigations have emphasized the variability in the knee extensor apparatus, with particular attention to a fifth component of the quadriceps femoris termed the tensor vastus intermedius or accessory "quinticeps femoris." Disorders of this structure have not been described in the pediatric imaging literature.To review the clinical features, pathoanatomy and imaging findings of children presenting with derangement of the accessory quadriceps femoris, with a particular emphasis on the utility of early magnetic resonance imaging (MRI) of the thigh.This is a retrospective analysis of 3 children, ages 3-10 years at presentation, who underwent imaging evaluation with subsequent surgically proven accessory quadriceps femoris muscles. Their clinical histories, including duration of symptoms, MRI findings, intervention and surgical outcomes, are reported.All patients presented with progressive unilateral restricted knee flexion and had multiple imaging studies targeting the knee before diagnosis. Diagnosis in all patients was made on MRI of the thighs, which demonstrated a fusiform low signal intensity structure with muscle-like architecture arising from the anterior or anterolateral proximal femur and blending with the common quadriceps tendon distally. All patients underwent surgical release of the anomalous band with significant functional improvement.In cases of progressive limited knee flexion without intrinsic pathology, an accessory quadriceps muscle should be considered as an extrinsic cause. Our experience demonstrated this to be readily identifiable on MRI, with symptomatic improvement following surgical release. Early recognition of this condition should prevent unnecessary intervention such as knee arthroscopy and the debilitating loss of flexion due to delayed diagnosis.

Congenital absence of the common bile duct (CBD), also known as âcholecystohepatic ductâ or âinterposition of the gallbladderâ is a rare extrahepatic biliary anomaly characterized by the hepatic ducts entering the gallbladder directly and the cystic duct draining the entire biliary tree into the duodenum. There have been only been four reports of children with congenital absence of the CBD, with three of these also carrying a diagnosis of esophageal atresia, suggesting an association between the two entities. We report an additional case of a child with a history of tracheoesophageal fistula and congenital absence of the CBD as well a review of the literature. Keywords: Gallbladder interposition, Biliary tract anomaly, Pediatric cholecystitis, Acalculous cholecystitis, Roux-en-y hepaticojejunostomy

The role of magnetic resonance imaging (MRI) in pediatric appendicitis is increasing; MRI findings predictive of appendiceal perforation have not been specifically evaluated. To assess the performance of MRI in differentiating perforated from non-perforated appendicitis. A retrospective review of pediatric patients undergoing contrast-enhanced MRI and subsequent appendectomy was performed, with surgicopathological confirmation of perforation. Appendiceal diameter and the following 10 MRI findings were assessed: appendiceal restricted diffusion, wall defect, appendicolith, periappendiceal free fluid, remote free fluid, restricted diffusion within free fluid, abscess, peritoneal enhancement, ileocecal wall thickening and ileus. Two-sample t-test and chi-square tests were used to analyze continuous and discrete data, respectively. Sensitivity and specificity for individual MRI findings were calculated and optimal thresholds for measures of accuracy were selected. Seventy-seven patients (mean age: 12.2 years) with appendicitis were included, of whom 22 had perforation. The perforated group had a larger mean appendiceal diameter and mean number of MRI findings than the non-perforated group (12.3 mm vs. 8.6 mm; 5.0 vs. 2.0, respectively). Abscess, wall defect and restricted diffusion within free fluid had the greatest specificity for perforation (1.00, 1.00 and 0.96, respectively) but low sensitivity (0.36, 0.25 and 0.32, respectively). The receiver operator characteristic curve for total number of MRI findings had an area under the curve of 0.92, with an optimal threshold of 3.5. A threshold of any 4 findings had the best ability to accurately discriminate between perforated and non-perforated cases, with a sensitivity of 82% and specificity of 85%. Contrast-enhanced MRI can differentiate perforated from non-perforated appendicitis. The presence of multiple findings increases diagnostic accuracy, with a threshold of any four findings optimally discriminating between perforated and non-perforated cases. These results may help guide management decisions as MRI assumes a greater role in the work-up of pediatric appendicitis.

We present a 3-month-old boy with a type IIA sling left pulmonary artery associated with imperforate anus and rectourethral fistula. Tracheobronchial abnormalities are demonstrated using multidetector CT with 3-D volume rendering of the airways. This case represents a novel variant of an already rare entity with an unusually high right upper lobe bronchus and no evidence of associated tracheobronchial stenosis.

Imaging predictors for surgery in children with Crohn disease are lacking. To identify imaging features of the terminal ileum on short-interval bowel ultrasound (US) and MR enterography (MRE) in children with Crohn disease requiring surgical bowel resection and those managed by medical therapy alone. This retrospective study evaluated patients 18 years and younger with Crohn disease undergoing short-interval bowel US and MRE (within 2 months of one another), as well as subsequent ileocecectomy or endoscopy within 3 months of imaging. Appearance of the terminal ileum on both modalities was compared between surgical patients and those managed with medical therapy, with the following parameters assessed: bowel wall thickness, mural stratification, vascularity, fibrofatty proliferation, abscess, fistula and stricture on bowel US; bowel wall thickness, T2 ratio, enhancement pattern, mesenteric edema, fibrofatty proliferation, abscess, fistula and stricture on MRE. A two-sided t-test was used to compare means, a Mann–Whitney U analysis was used for non-parametric parameter scores, and a chi-square or two-sided Fisher exact test compared categorical variables. Imaging findings in surgical patients were correlated with location-matched histopathological scores of inflammation and fibrosis using a scoring system adapted from the Simple Endoscopic Score for Crohn Disease, and a Spearman rank correlation coefficient was used to compare inflammation and fibrosis on histopathology. Twenty-two surgical patients (mean age: 16.5 years; male/female: 13/9) and 20 nonsurgical patients (mean age: 14.8; M/F: 8/12) were included in the final analysis. On US, the surgical group demonstrated significantly increased mean bowel wall thickness (6.1 mm vs. 4.7 mm for the nonsurgical group; P = 0.01), loss of mural stratification (odds ratio [OR] = 6.3; 95% confidence interval [CI]: 1.4-28.4; P = 0.02) and increased fibrofatty proliferation (P = 0.04). On MRE, the surgical group showed increased mean bowel wall thickness (9.1 mm vs. 7.2 mm for the nonsurgical group; P = 0.02), increased mean T2 ratio (4.6 vs. 3.6 for the nonsurgical group; P = 0.03), different enhancement patterns (P = 0.03), increased mesenteric edema (P = 0.001) and increased stricture formation (OR = 8.2; 95% CI: 1.8-36.4; P = 0.005). Nineteen of 22 ileocecectomy specimens showed severe inflammation and 21/22 showed severe fibrosis, with significant correlation between inflammation and fibrosis scores (ρ = 0.55; P = 0.008); however, correlation with imaging findings was limited by the uniformity of findings on histopathology. Children with terminal ileal Crohn disease requiring surgical bowel resection demonstrate more severe manifestations of imaging features traditionally associated with both active inflammation and chronic fibrosis than those managed medically on US and MRE, findings that are corroborated by histopathology. These features may potentially serve as imaging biomarkers indicating the necessity for surgical intervention.

Developmental dysplasia of the hip is a spectrum disorder of hip development that ranges in severity from abnormal acetabular morphology to complete hip dislocation. While treatment with a Pavlik harness is highly effective in infants younger than 6 months, older infants and children and those with orthotic failure often warrant surgical reduction and placement of a spica cast, which limits subsequent imaging evaluation. Magnetic resonance (MR) imaging has been described in the evaluation of the adequacy of hip reduction for more than 2 decades, but the practice is still not widespread and is performed routinely at relatively few centers. MR imaging is a robust tool for outcome assessment after hip reduction and placement of a spica cast, facilitating multiplanar confirmation of concentric reduction independent of an ossific nucleus or orthopedic hardware. Excellent image contrast of soft tissues allows identification of obstacles to concentric reduction, which may be extra-articular or intra-articular. Extra-articular obstacles include tightening of the adductor muscles and tightening of the iliopsoas tendon with constriction of the joint capsule. Intra-articular obstacles include limbus formation, labral inversion, an enlarged pulvinar, and hypertrophy of the ligamentum teres and/or the transverse acetabular ligament. Intravenous contrast material administration may demonstrate altered epiphyseal blood flow and help identify patients at risk for early ischemia. Imaging technique and image interpretation can be optimized to facilitate the performance of postreduction MR imaging studies where they may be of benefit. (©)RSNA, 2016.

Magnetic resonance (MR) imaging may provide a radiation-sparing alternative to CT in diagnosing appendicitis in children in whom US is equivocal. However, comparability with CT in the detection of the appendix remains to be established. To determine the detection rate of the normal appendix in children on oral and IV contrast-enhanced MRI. MR imaging of 58 patients who had previously undergone MR enterography was retrospectively reviewed. Detection rate, body mass index, age and gender were recorded. The normal appendix was detected in 28 cases (48 %), with greatest detection rate on the axial fast imaging employing steady-state acquisition (FIESTA) sequence. Children in whom the appendix was detected had significantly higher BMI compared to children in whom the appendix was not seen. Neither age nor gender demonstrated a significant association with detection rate. The detection rate of the normal appendix in children on oral and IV contrast-enhanced MRI was 48 %, which is comparable to detection rates on CT, as well as to previously reported detection rates on MR imaging with neither oral nor IV contrast agents. These findings may serve to guide the development of MRI protocols for pediatric appendicitis.

We present a case of NUT midline carcinoma (NMC) mimicking lymphoma in an adolescent boy, with attention to multidetector CT appearance and pattern of metastasis on [F-18]2-fluoro-2-deoxyglucose positron emission tomography (FDG PET/CT). Few case reports have focused on the imaging characteristics of this rare tumor in the pediatric imaging literature. A newly described but increasingly recognized disease entity, NMC should enter the differential of pediatric midline tumors displaying particularly aggressive characteristics on imaging.

Crohn’s disease has been associated with restricted diffusion in diseased small bowel segments on diffusion-weighted imaging (DWI). However, data addressing longitudinal changes in DWI findings and their potential clinical ramifications in the pediatric population are lacking. The purpose of this study was to follow DWI changes in diseased small bowel segments between serial magnetic resonance enterography (MRE) examinations, and to correlate these changes with other imaging parameters and clinical status. This retrospective study evaluated patients less than 21 years of age undergoing serial MRE examinations including DWI for Crohn’s disease involving the small bowel. All patients carried a diagnosis of Crohn’s disease established by pathology or corroborative clinical and imaging findings. Longitudinal changes in mean apparent diffusion coefficient (ADC) values within the wall of affected small bowel lesions were recorded and normalized to both unaffected bowel and skeletal muscle. ADC changes were correlated with qualitative imaging phenotype, as reflected by a defined set of non-DWI imaging parameters, as well as with clinical disease activity. Seventeen lesions were evaluated longitudinally, distributed among 13 patients (9 boys and 4 girls, mean age at baseline 16.6 years), each of whom had two sequential MRE examinations. Lesions demonstrating a fibrostenotic imaging phenotype at follow-up MRE had a significantly lower change in mean ADC value between examinations than lesions that did not have a fibrostenotic imaging phenotype (p = 0.0005), an effect that persisted when ADC values were normalized to unaffected bowel and skeletal muscle. Across all studies, lesions with a fibrostenotic imaging phenotype had lower ADC values than those with an inflammatory imaging phenotype, which were in turn lower than those with a normal imaging phenotype (p = 0.0001). Patterns of longitudinal DWI changes in Crohn’s disease may differ among small bowel lesions depending upon their specific natural histories. These findings may assist in the evaluation of the ADC value as a potential imaging surrogate when evaluating lesion status, particularly as it pertains to relative contributions of inflammation and fibrosis.

Pancreatic involvement in neuroblastoma is extremely rare, with few cases reported in the literature. We present imaging findings of pancreatic involvement in neuroblastoma with clinical and pathologic correlation in the largest documented series to date.We prospectively reported pancreatic involvement evident on multimodality imaging in neuroblastoma patients presenting to our institution from 1997 to 2011. Lesions were classified according to location within the pancreas, and imaging features were correlated with cytogenetic and surgicopathologic findings.Neuroblastoma involving the pancreas was evident on imaging of seven of 1031 patients (mean age, 6.6 years). One patient had pancreatic involvement at presentation, and six developed pancreatic disease at relapse or disease progression. Pancreatic lesions were most frequently initially identified on concurrent CT and (123)I-metaiodobenzylguanidine scintigraphy, and additional lesions initially were found on MRI and ultrasound. Five of seven patients had focal lesions, one had diffuse pancreatic involvement, and one had pancreatic extension from contiguous disease. The distribution of lesions favored the pancreatic body and tail. All patients had International Neuroblastoma Staging System stage 3 or 4 disease, Children's Oncology Group intermediate- or high-risk disease, and unfavorable histology at initial diagnosis. For the five patients with surgical correlation, pancreatic surgical specimens revealed neuroblastoma in three cases and ganglioneuroblastoma in two cases.Although rare, pancreatic involvement in neuroblastoma occurs. Its variable imaging appearance should be considered when evaluating the retroperitoneum in patients with known or suspected neuroblastoma, particularly because increased patient survival holds the potential for uncommon patterns of recurrence.