MRI of paediatric liver tumours: How we review and report

Accuracy of contrast-enhanced CT in liver neoplasms in children under 2 years age

BACKGROUND

Multiple differentials exist for pediatric liver tumors under 2 years. Accurate imaging diagnosis may obviate the need for tissue sampling in most cases.

OBJECTIVE

To evaluate the imaging features and diagnostic accuracy of computed tomography (CT) in liver tumors in children under 2 years.

METHODS

Eighty-eight children under 2 years with treatment naive liver neoplasms and baseline contrast-enhanced CT were included in this institutional review board approved retrospective study. Two blinded onco-radiologists assessed these tumors in consensus. Findings assessed included enhancement pattern, lobulated appearance, cystic change, calcifications, central scar-like appearance, and metastases. The radiologists classified the lesion as hepatoblastoma, infantile hemangioma, mesenchymal hamartoma, rhabdoid tumor, or indeterminate, first based purely on imaging and then after alpha-fetoprotein (AFP) correlation. Multivariate analysis and methods of comparing means and frequencies were used for statistical analysis wherever applicable. Diagnostic accuracy, sensitivity, and positive predictive values were analyzed.

RESULTS

The mean age of the sample was 11.4 months (95% CI, 10.9-11.8) with 50/88 (57%) boys. The study included 72 hepatoblastomas, 6 hemangiomas, 4 mesenchymal hamartomas, and 6 rhabdoid tumors. Presence of calcifications, multilobular pattern of arterial enhancement, lobulated morphology, and central scar-like appearance was significantly associated with hepatoblastomas (P-value < 0.05). Fourteen out of eighty-eight lesions were called indeterminate based on imaging alone; six lesions remained indeterminate after AFP correlation. Pure radiology-based diagnostic accuracy was 81.8% (95% CI, 72.2-89.2%), which increased to 92.1% (95% CI, 84.3-96.7%) (P-value > 0.05) after AFP correlation, with one hepatoblastoma misdiagnosed as a rhabdoid tumor. If indeterminate lesions were excluded for biopsy, the accuracy would be 98.8% (95% CI, 93.4-99.9%).

CONCLUSION

CT had high accuracy for diagnosing liver neoplasms in the under 2-year age population after AFP correlation. Certain imaging features were significantly associated with the diagnosis of hepatoblastoma. A policy of biopsying only indeterminate lesions after CT and AFP correlation would avoid sampling in the majority of patients.

Staging and Restaging Pediatric Abdominal and Pelvic Tumors: A Practical Guide

The most common abdominal malignancies diagnosed in the pediatric population include neuroblastoma, Wilms tumor, hepatoblastoma, lymphoma, germ cell tumor, and rhabdomyosarcoma. There are distinctive imaging findings and patterns of spread for each of these tumors that radiologists must know for diagnosis and staging and for monitoring the patient's response to treatment. The multidisciplinary treatment group that includes oncologists, surgeons, and radiation oncologists relies heavily on imaging evaluation to identify the best treatment course and prognostication of imaging findings, such as the image-defined risk factors for neuroblastomas, the PRETreatment EXtent of Disease staging system for hepatoblastoma, and the Ann Arbor staging system for lymphomas. It is imperative for radiologists to be able to correctly indicate the best imaging methods for diagnosis, staging, and restaging of each of these most prevalent tumors to avoid inconclusive or unnecessary examinations. The authors review in a practical manner the most updated key points in diagnosing and staging disease and assessing response to treatment of the most common pediatric abdominal tumors. ©RSNA, 2024 Supplemental material is available for this article.

Pediatric Hepatoblastoma After Neoadjuvant Chemotherapy: Diagnostic Performance of MR in Staging POSTTEXT and Vascular Involvement

BACKGROUND

The assessment of resectability after neoadjuvant chemotherapy of hepatoblastoma is dependent on Post-Treatment EXTENT of Disease (POSTTEXT) staging and its annotation factors P (portal venous involvement) and V (hepatic venous/inferior vena cava [IVC] involvement), but MR performance in assessing them remains unclear.

PURPOSE

To assess the diagnostic performance of contrast-enhanced MR imaging for preoperative POSTTEXT staging and diagnosing vascular involvement in terms of annotation factors P and V in pediatric hepatoblastoma following neoadjuvant chemotherapy.

STUDY TYPE

Retrospective.

SUBJECTS

Thirty-five consecutive patients (17 males, median age, 24 months; age range, 6-98 months) with proven hepatoblastoma underwent preoperative MR imaging following neoadjuvant chemotherapy.

FIELD STRENGTH/SEQUENCE

3.0 T; T2-weighted imaging (T2WI), T2WI with fat suppression, diffusion weighted imaging, radial stack-of-the-star/Cartesian 3D Dixon T1-weighted gradient echo imaging.

ASSESSMENT

Three radiologists independently assessed the POSTTEXT stages and annotation factors P and V based on the 2017 PRE/POSTTEXT system. The sensitivities and specificities were calculated for 1) diagnosing each POSTTEXT stage; 2) discrimination of stages III and IV (advanced) from those stages I and II (non-advanced) hepatoblastomas; and 3) annotation factors P and V. The combination of pathologic findings and surgical records served as the reference standard.

STATISTICAL TESTS

Sensitivity, specificity, Fleiss kappa test.

RESULTS

The sensitivity and specificity ranges for discriminating advanced from non-advanced hepatoblastomas were 73.3%-80.0% and 80.0%-90.0%, respectively. For annotation factor P, they were 66.7%-100.0% and 90.6%, respectively. For factor V, they were 75.0% and 67.7%-83.9%, respectively. There was excellent, substantial, and moderate agreement on POSTTEXT staging (Fleiss kappa = 0.82), factors P (Fleiss kappa = 0.64), and factors V (Fleiss kappa = 0.60), respectively.

DATA CONCLUSION

MR POSTTEXT provides reliable discrimination between advanced and non-advanced tumors, and MR has moderate to excellent specificity at identifying portal venous and hepatic venous/IVC involvement.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 3.

Review on Pediatric Malignant Focal Liver Lesions with Imaging Evaluation: Part I

Malignant focal liver lesions (FLLs) are commonly reported in adults but rarely seen in the pediatric population. Due to the rarity, the understanding of these diseases is still very limited. In children, most malignant FLLs are congenital. It is very important to choose appropriate imaging examination concerning various factors. This paper will outline common pediatric malignant FLLs, including hepatoblastoma, hepatocellular carcinoma, and cholangiocarcinoma and discuss them against the background of the latest knowledge on comparable/similar tumors in adults. Medical imaging features are of vital importance for the non-invasive diagnosis and follow-up of treatment of FLLs in pediatric patients. The use of CEUS in pediatric patients for characterizing those FLLs that remain indeterminate on conventional B mode ultrasounds may be an effective option in the future and has great potential to be integrated into imaging algorithms without the risk of exposure to ionizing radiation.

Imaging of pediatric liver tumors: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper

Primary hepatic malignancies are relatively rare in the pediatric population, accounting for approximately 1%-2% of all pediatric tumors. Hepatoblastoma and hepatocellular carcinoma are the most common primary liver malignancies in children under the age of 5 years and over the age of 10 years, respectively. This paper provides consensus-based imaging recommendations for evaluation of patients with primary hepatic malignancies at diagnosis and follow-up during and after therapy.

Strategy for Accurate Diagnosis by Contrast-Enhanced Ultrasound of Focal Liver Lesions in Patients Not at High Risk for Hepatocellular Carcinoma: A Preliminary Study

OBJECTIVE

To develop an effective strategy for accurate diagnosis of focal liver lesions (FLLs) in patients with non-high risk for hepatocellular carcinoma (HCC).

METHODS

From January 2012 to December 2015, consecutive patients with non-high risk for HCC who underwent contrast-enhanced ultrasound (CEUS) were included in this retrospective double-reader study. All patients were stratified into 2 different risks (intermediate, low-risk) groups according to criteria based on clinical characteristics, known as clinical risk stratification criteria. For the intermediate-risk group, the CEUS criteria for identifying benign lesions and HCCs were constructed based on selected CEUS features. The diagnostic performance of the clinical risk stratification criteria, and CEUS criteria for identifying benign lesions and HCCs was evaluated.

RESULTS

This study included 348 FLLs in 348 patients. The sensitivity and specificity of the clinical risk stratification criteria for malignancy was 97.8 and 69.8%. Patients were classified as intermediate risk if they were male, or older than 40 years of age, or HBcAb positive, or having positive tumor markers. Otherwise, patients were classified as low risk. Among the 348 patients, 327 were in the intermediate-risk group and 21 were in the low-risk group. In the intermediate-risk group, the CEUS criteria for identifying benign lesions were any of the following features: 1) hyper/isoenhancement in the arterial phase without washout, 2) nonenhancement in all phases, 3) peripheral discontinuous globular enhancement in the arterial phase, 4) centrifugal enhancement or peripheral enhancement followed by no central enhancement, or 5) enhanced septa. The accuracy, sensitivity, and specificity of the CEUS criteria for identifying benign lesions were 94.5, 83.0, and 99.6%, respectively. Arterial phase hyperenhancement followed by mild and late washout (>60 seconds) was more common in HCC patients than in non-HCC patients (P < .001). Using arterial phase hyperenhancement followed by mild and late washout as the CEUS criteria for identifying HCCs, the sensitivity and specificity were 52.6 and 95.3%, but unfortunately, the positive predictive value was only 82.0%. For the low-risk group, no further analysis was performed due to the small sample size.

CONCLUSIONS

Initial clinical risk stratification followed by assessment of certain CEUS features appears to be a promising strategy for the accurate diagnosis of FLLs in patients not at high risk for HCC.

Imaging strategy for focal nodular hyperplasia in children: long-term experience from two specialist European centres

BACKGROUND

Focal nodular hyperplasia (FNH) in children is a rare but benign tumour, which must be differentiated from malignant entities to avoid unnecessary treatment, leading to potential morbidity.

OBJECTIVES

To provide data on imaging findings of these lesions with a suggested algorithm for diagnosis, sampling and follow-up.

MATERIALS AND METHODS

This retrospective review evaluated imaging of all patients diagnosed with FNH in two tertiary referral centres in Europe between 1975 and 2018.

RESULTS

One hundred and four patients with 137 tumours were reviewed. The mean age at presentation was 8.2 years. The median tumour size was 5 cm (range: 0.3-29 cm). Multiple lesions were seen in 16.3% of patients. The male-to-female ratio was 1:2.

CONCLUSION

FNH with typical features on imaging can be safely followed up once the diagnosis has been established. The use of contrast-enhanced ultrasound and magnetic resonance imaging allows accurate characterisation in most cases. Histological sampling is only advised when there is diagnostic doubt. Atypical arterial enhancement of FNH should prompt the search for a congenital portosystemic shunt.

Hepatocellular carcinoma requiring liver transplantation in hereditary tyrosinemia type 1 despite nitisinone therapy and α1-fetoprotein normalization

BACKGROUND

Hereditary tyrosinemia type 1 is a rare metabolic condition associated with an increased risk of hepatocellular carcinoma. Nitisinone (2-[2-nitro-4-trifluoromethylbenzoyl]-1,3-cyclohexanedione, NTBC) treatment has reduced but not eliminated the risk. The delayed initiation of nitisinone treatment, and persistently abnormal α1-fetoprotein (AFP) levels are recognized to be risk factors for late-onset hepatocellular carcinoma. We report three children diagnosed and treated with nitisinone since infancy who developed hepatocellular carcinoma despite long-term normalization of AFP.

METHODS

A retrospective review of all patients with tyrosinemia on nitisinone managed at our center was undertaken. Patient demographics, age at diagnosis, duration of therapy, timing of AFP normalization, and radiographic imaging findings were noted.

RESULTS

Three patients at our center with tyrosinemia type 1 developed hepatocellular carcinoma 9-13 years after diagnosis despite long-term nitisinone therapy and normalization of AFP. Two patients developed new nodules on imaging with an elevation of AFP leading to the diagnosis and subsequent liver transplant. The third patient proceeded with liver transplant because of a very nodular liver and increasing splenomegaly despite normal AFP and no change in surveillance gadoxetate magnetic resonance imaging. Early hepatocellular carcinoma was found in her liver explant. All three patients were cirrhotic at diagnosis.

CONCLUSIONS

Patients with hereditary tyrosinemia type 1, especially those already cirrhotic at diagnosis, remain at high risk of developing hepatocellular carcinoma despite long-term nitisinone therapy and AFP normalization, and warrant close monitoring and surveillance.

Imaging findings of spontaneous intraabdominal hemorrhage: neoplastic and non-neoplastic causes

Contrary to traumatic and iatrogenic intraabdominal hemorrhages, spontaneous intraabdominal hemorrhage is a challenging clinical situation. A variety of neoplastic and non-neoplastic conditions may cause spontaneous intraabdominal bleeding. Imaging findings vary depending on the source of bleeding and the underlying cause. In this article, we aim to increase the awareness of imagers to the most common causes of spontaneous intraabdominal hemorrhage by using representative cases.

Liver Transplantation in Malignancies: A Comprehensive and Systematic Review on Oncological Outcome

Introduction

Liver transplantation (LT) is today's standard treatment for both end-stage liver disease and tumors; however, suitable grafts for LT are a scarce resource and outcome after LT is highly dependent on its underlying indication. Thus, patients must be carefully selected to optimize the number of life years gained per graft. This comprehensive and systematic review critically reflects the most recently published oncological outcome data after LT in malignancies based on the preoperative radiological findings.

Methods

A systematic literature search was conducted to detect preferentially most recent high-volume series or large database analysis on oncological outcomes after LT for both primary liver cancer and liver metastases between January 1, 2019, and November 14, 2020. A comprehensive review on the radiological assessment of the reviewed liver malignancies is included and its preoperative value for an outcome-driven indication reflected.

Results

Twenty most recent high-volume or relevant studies including a total number of 2,521 patients were identified including 4, 4, 4, 4, 3, and 1 publications on oncological outcome after LT for hepatocellular carcinoma, cholangiocellular carcinoma, hepatic epitheloid hemangioendothelioma, hepatoblastoma, and both metastatic neuroendocrine tumors and colorectal cancer, respectively. The overall survival is comparable to patients without tumors if patients with malignancies are well selected for LT; however, this is highly dependent on tumor entity, tumor stage, and both neoadjuvant and concomitant treatment.

Discussion/Conclusion

LT is a promising option for better survival in patients with malignant liver tumors in selected patients; however, the indication must be critically discussed prior to LT in every single case in the context of organ shortage.

Liver Tumours in Children: The Hepatologist's View

ABSTRACT

Diagnostic and therapeutic innovations have changed the way we now approach liver tumours in children and adolescents. Novel imaging tools, increasing awareness, and surveillance has led to early diagnosis of benign and malignant liver tumours. Multidisciplinary interventions have favourably altered the natural course in some liver tumours. The role of liver transplantation is expanding and has become fully integrated into today's therapeutic algorithms. Transarterial locoregional and ablation therapies have been successful in adults and are being explored in children to facilitate resectability and improve outcome. For the first time, North American, Japanese, and European experts have designed a global trial to optimize management of malignant liver tumours and aim to find signature molecular profiles that will translate to individualised treatment strategies.This article aims to offer an overview of recent advances in our understanding of liver tumours in children. It focuses on the paediatric hepatologist's view and their role in the multidisciplinary management of benign and malignant liver tumours.

Diagnostic Performance of LI-RADS Version 2018 for Evaluation of Pediatric Hepatocellular Carcinoma

Background The Liver Imaging Reporting and Data System (LI-RADS) has standardized the evaluation of adult but not pediatric hepatocellular carcinoma (HCC). Purpose To evaluate the performance of LI-RADS version 2018 for diagnosis of pediatric HCC. Materials and Methods This multi-institution retrospective study evaluated all available dynamic CT and/or MRI scans of pediatric (≤18 years) HCC from five institutions between July 2009 and April 2019. The control group included an equal number of other enhancing hepatic lesions. Blinded to final diagnosis, three radiologists independently applied LI-RADS version 2018 criteria. The reference standard was pathologic examination or more than 1 year follow-up. Sensitivity and specificity of LI-RADS were computed using a dichotomous classification of LR-1, LR-2, or LR-3 versus LR-4, LR-5, LR-TIV (tumor in vein), or LR-M (probably or definitely malignant but not HCC-specific) for predicting hepatic malignancy in the entire cohort and in patients at risk for HCC. Results The cohort consisted of 116 children: 58 with HCC (mean age, 12 years ± 5; 31 girls) and 58 with other enhancing hepatic masses (mean age, 12 years ± 5; 42 girls). Frequencies of major criteria in classic HCC for the three readers were as follows: nonrim arterial phase hyperenhancement, 49%-62% (19-24 of 39 patients); nonperipheral "washout," 36%-59% (14-23 of 39 patients); and enhancing "capsule," 28%-38% (11-15 of 39 patients). For the full cohort, the sensitivity of LR-4, LR-5, LR-TIV, or LR-M for malignancy among the three readers ranged from 85% (95% CI: 76, 94) to 88% (95% CI: 80, 96); specificity of LR-1, LR-2, or LR-3 for benignity ranged from 54% (95% CI: 40, 68) to 70% (95% CI: 57, 83). In the at-risk subgroup, sensitivity ranged from 58% (95% CI: 36, 80) to 68% (95% CI: 48, 89); specificity ranged from 56% (95% CI: 37, 74) to 63% (95% CI: 45, 81). All lesions categorized as LR-TIV (n = 10-13) were HCCs. Conclusion Liver Imaging Reporting and Data System version 2018 had moderate sensitivity but low specificity for the diagnosis of pediatric hepatocellular carcinoma (HCC), which had low frequencies of the major criteria used for adult HCC diagnosis. © RSNA, 2021 See also the editorial by Paltiel in this issue.

Pediatric Hepatoblastoma: What the Sonographer Needs to Know for the Sonographic Evaluation of Complications After Treatment and After Liver Transplantation

Hepatoblastoma (HB) is a common primary pediatric liver tumor, and its typical presentation is a palpable, nontender abdominal mass that is detected through sonographic imaging. The current treatment standard for HB includes chemotherapy followed by liver resection or transplantation. Throughout the management of HB, high-quality sonographic images inform diagnosis, treatment interventions, and detection of surgical treatment complications. It is important that sonographers be familiar with the presentation and complications of HB on imaging examinations. The authors review sonographic detection, evaluation of HB at presentation, and common complications after liver resection and transplantation.

Rare primary hepatic malignancies: A case-based review

The two most common primary liver malignancies that radiologists encounter in clinical practice are hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC). However, there are other less common primary hepatic malignancies that radiologists should be aware of. The correct radiographic and pathologic diagnosis of these entities have important treatment and prognostic implications. In this paper, we review a series of five cases that we have encountered in clinical practice at our institution that were initially thought to be HCC or ICC, but turned out to be a rarer primary hepatic malignancy. We will review the radiographic and pathologic characteristics of each of these rare primary hepatic malignancies as well as discuss the prognosis and treatment for each.

Liver Transplantation for Pediatric Liver Cancer

Unresectable hepatocellular carcinoma (HCC) was first removed successfully with total hepatectomy and liver transplantation (LT) in a child over five decades ago. Since then, children with unresectable liver cancer have benefitted greatly from LT and a confluence of several equally important endeavors. Regional and trans-continental collaborations have accelerated the development and standardization of chemotherapy regimens, which provide disease control to enable LT, and also serve as a test of unresectability. In the process, tumor histology, imaging protocols, and tumor staging have also matured to better assess response and LT candidacy. Significant trends include a steady increase in the incidence of and use of LT for hepatoblastoma, and a significant improvement in survival after LT for HCC with each decade. Although LT is curative for most unresectable primary liver sarcomas, such as embryonal sarcoma, the malignant rhabdoid tumor appears relapse-prone despite chemotherapy and LT. Pediatric liver tumors remain rare, and diagnostic uncertainty in some settings can potentially delay treatment or lead to the selection of less effective chemotherapy. We review the current knowledge relevant to diagnosis, LT candidacy, and post-transplant outcomes for these tumors, emphasizing recent observations made from large registries or larger series.

Imaging of a glomus tumor of the liver in a child

Glomus tumors occur preferentially in the subcutaneous tissue of the fingers and toes, but are extremely rare in visceral organs. Although, there have been several reports of glomus tumors in the liver in adult patients, there have yet been no publications reporting glomus tumors of the liver in children. Here, we report a case of an 11-year-old girl who was admitted with a 2-week history of progressive dyspnea on exertion and vomiting. Upon physical examination, she was found to have hypertension and a palpated smooth, firm mass at the epigastrium. Abdominal MRI revealed a well-defined exophytic hypervascular mass with intratumoral hemorrhage at segment 3/4b of the liver. Ultrasound-guided biopsy revealed it to be a glomus tumor. An ultrasound conducted at a 1-month follow-up after preoperative embolization revealed that the mass had decreased in size. A subsequent exploratory laparotomy with left hepatectomy was performed and the histologic results confirmed the diagnosis.

[Imaging of abdominal tumors in childhood and adolescence : Part I: Background, hepatic, splenic and pancreatic tumors]

In comparison to adult patients, other specific entities of abdominal tumors occur in childhood and adolescence. These include malignant tumors originating from embryonic tissue, such as hepatoblastoma. Some of the abdominal tumors are already diagnosed prenatally or in neonates. Sonography functions as the primary radiological basic diagnostics of pediatric abdominal space-occupying lesions, if necessary supplemented by administration of ultrasound contrast medium or the implementation of novel techniques (e.g. innovative Doppler and elastography procedures). Magnetic resonance imaging (MRI) is used for a comprehensive and detailed depiction of the tumors including the question of resectability and vascular supply. Various weighting and different MRI sequences are used in order to be able to assess the signal behavior of the tumor and therefore the possible presence of calcification, necrosis or hemorrhage, the behavior of dynamic contrast enhancement, and the presence and extent of diffusion disorders. This information is decisive in order to be able to assess the entity and malignancy of the abdominal space-occupying lesion. Rare but relevant tumors with respect to the entity occur in childhood and adolescence in the abdominal organs liver, spleen and pancreas.

Use of Eovist in Pediatric Patients: Pearls and Pitfalls

Magnetic resonance imaging is excellent at characterizing pediatric hepatobiliary pathology. Noncontrast MRI is helpful due to T2 hyperintensity associated with bile, but contrast enhancement offers additional means of lesional characterization. In particular, hepatocyte-specific contrast agents such as gadoxetate disodium (Eovist) exhibit partial hepatobiliary excretion which may be leveraged in these contexts. In this review, we will discuss gadoxetate disodium usage, including a sample-imaging protocol, and demonstrate applications and limitations in the pediatric population.

Contrast-enhanced ultrasound in the diagnosis of pediatric focal nodular hyperplasia and hepatic adenoma: interobserver reliability

BACKGROUND

Focal nodular hyperplasia and hepatic adenoma are rare liver tumors in which specific features on contrast-enhanced ultrasound (US) have been reported but are little known in children.

OBJECTIVE

To assess the interobserver agreement in diagnosing and differentiating focal nodular hyperplasia and hepatic adenoma in children using established adult contrast-enhanced US characteristics.

MATERIALS AND METHODS

Thirty children with a definite or probable diagnosis of focal nodular hyperplasia or hepatic adenoma on magnetic resonance imaging (MRI)/histology who underwent contrast-enhanced US studies were included. Typical and additional contrast-enhanced US features of focal nodular hyperplasia and hepatic adenoma were included. The lesions were classified as definite/probable focal nodular hyperplasia, definite/probably hepatic adenoma or unclassified. The interobserver kappa of contrast-enhanced US characteristics was calculated.

RESULTS

Focal nodular hyperplasia and hepatic adenoma in children demonstrate contrast-enhanced US characteristics similar to those in adults. Among the nine lesions with confirmed histological diagnosis, correct diagnosis was made in 7 (77.8%) based on contrast-enhanced US criteria. Two lesions were unclassified by both observers due to a mixed arterial filling pattern. Interobserver kappa for contrast-enhanced US diagnosis was 0.64 (P<0.0001).

CONCLUSION

There is a good interobserver kappa for separating focal nodular hyperplasia from hepatic adenoma in children using established adult contrast-enhanced US features.

Magnetic resonance imaging features of common focal liver lesions in children

Magnetic resonance imaging (MRI) is commonly used to characterize focal liver masses in the pediatric population. MRI is the preferred modality because of its superior contrast resolution and utility for obtaining functional sequences such as diffusion-weighted imaging (DWI). MR exams performed with a hepatocyte-specific gadolinium-based contrast agent can characterize focal liver lesions, which helps in differentiating a common benign entity such as focal nodular hyperplasia from other liver pathology when the background liver is normal. The most common benign focal lesion is a hemangioma, and metastases followed by hepatoblastoma are the most common malignant lesions. This article can help radiologists become familiar with the pre- and post-contrast imaging features of common pediatric liver masses.

Staging and following common pediatric malignancies: MRI versus CT versus functional imaging

Most pediatric malignancies require some form of cross-sectional imaging, either for staging or response assessment. The majority of these are solid tumors and this review addresses the role of MRI, as well as other cross-sectional and functional imaging techniques, for evaluating the most common pediatric solid tumors. The primary emphasis is on neuroblastoma, hepatoblastoma and Wilms tumor, three of the most common non-central-nervous-system (CNS) pediatric solid tumors encountered in young children. The initial focus will be a review of the imaging techniques and approaches used for diagnosis, staging and early post-treatment response assessment, followed by a discussion of the role surveillance imaging plays in pediatric oncology and a brief review of other emerging imaging techniques. The lessons learned here can be applied to most other pediatric tumors, including rhabdomyosarcoma, Ewing sarcoma and osteosarcoma, as well as germ cell tumors, neurofibromatosis and other rare tumors. Although lymphoma, in particular Hodgkin lymphoma, represents one of the more common pediatric malignancies, this is not discussed in detail here. Rather, many of the lessons that we have learned from lymphoma, specifically with regard to how we integrate both anatomical imaging and functional imaging techniques, is applied to the discussion of the other pediatric solid tumors.

Pedunculated focal nodular hyperplasia in a healthy toddler

Focal nodular hyperplasia (FNH) is a benign hepatic tumor rarely seen in pediatric patients, with most cases reported in school-aged children with a history of malignancy, liver disease, chemotherapy, or hematopoietic stem cell therapy. Despite having advanced radiographic imaging, diagnosing FNH before surgical resection can be difficult. We report a rare case of pedunculated FNH presenting as a large abdominal mass palpated on physical exam in a healthy 3-year-old girl with no history of malignancy or underlying liver disease. Ultrasound, computed tomography, and magnetic resonance imaging (MRI) did not demonstrate the typical imaging characteristics of FNH, because the mass was pedunculated with a poorly visualized central scar. Because approximately 75% of all primary hepatic tumors in this age group are malignant, this report also discusses the importance of adding hepatobiliary phase imaging with MRI to avoid, if possible, the need for biopsy or surgical resection of a benign hepatic tumor.

Fractures in children with newly diagnosed hepatoblastoma

BACKGROUND

Hepatoblastoma is the most common primary hepatic malignancy in children. We have recently noticed an increased incidence of unsuspected fractures in children with newly diagnosed hepatoblastoma. This association has been suggested in the past, but the incidence and pathophysiology remain uncertain.

OBJECTIVE

To define the incidence and imaging features of fractures in children with newly diagnosed hepatoblastoma.

MATERIALS AND METHODS

We searched the oncology database and the radiology picture archiving and communication system of our large tertiary care children's hospital between January 2000 and August 2013 for all patients who presented to our institution with newly diagnosed hepatoblastoma. We reviewed all available imaging exams (radiographs, CT scans, MRIs, and nuclear medicine studies) to identify children who had radiologically apparent fractures on exams during the 50 days prior to diagnosis or up to 2 weeks after the date of hepatoblastoma diagnosis.

RESULTS

Forty-five children were included in this retrospective study. Eight children (17.8%) had fractures within 50 days prior to diagnosis or up to 2 weeks after the date of diagnosis, with a mean number of 4.9 fractures per patient (range 1-13). Only 21 of the 39 fractures (54%) were diagnosed during the initial image interpretation. Fractures most commonly occurred in the ribs (n=21) and vertebral bodies (n=10). The presence of a fracture was not associated with an identified demographic, tumor or laboratory finding.

CONCLUSION

Unsuspected fractures are relatively common in children with newly diagnosed hepatoblastoma.