Pediatric Hepatobiliary Neoplasms

Diagnosis and Follow-up of Incidental Liver Lesions in Children

Incidental liver lesions are identified in children without underlying liver disease or increased risk of hepatic malignancy in childhood. Clinical and imaging evaluation of incidental liver lesions can be complex and may require a multidisciplinary approach. This review aims to summarize the diagnostic process and follow-up of incidental liver lesions based on review of the literature, use of state-of-the-art imaging, and our institutional experience. Age at presentation, gender, alpha fetoprotein levels, tumor size, and imaging characteristics should all be taken into consideration to optimize diagnosis process. Some lesions, such as simple liver cyst, infantile hemangioma, focal nodular hyperplasia (FNH), and focal fatty lesions, have specific imaging characteristics. Recently, contrast-enhanced ultrasound (CEUS) was Food and Drug Administration (FDA)-approved for the evaluation of pediatric liver lesions. CEUS is most specific in lesions smaller than 3 cm and is most useful in the diagnosis of infantile hemangioma, FNH, and focal fatty lesions. The use of hepatobiliary contrast in MRI increases specificity in the diagnosis of FNH. Recently, lesion characteristics in MRI were found to correlate with subtypes of hepatocellular adenomas and associated risk for hemorrhage and malignant transformation. Biopsy should be considered when there are no specific imaging characteristics of a benign lesion. Surveillance with imaging and alpha fetoprotein (AFP) should be performed to confirm the stability of lesions when the diagnosis cannot be determined, and whenever biopsy is not feasible.

[Imaging of hepatic tumors in children and adolescents]

BACKGROUND

Pediatric liver tumors are relatively rare, but thorough knowledge of their imaging features is still important.

OBJECTIVES

Frequency and imaging features of benign and malignant liver masses during childhood and adolescence.

MATERIALS AND METHODS

Discussion of relevant original articles, review manuscripts and expert recommendations concerning imaging of childhood liver tumors.

RESULTS

The most common malignant tumors of the liver are hepatoblastoma, which usually occur in younger children, as well as in some regions hepatocellular carcinoma. In contrast to most benign masses, such as focal nodular hyperplasia, simple cysts or fatty liver infiltrations, their imaging morphology is not very characteristic. Radiologically, sonography and magnetic resonance imaging (MRI) are used for assessment. Both methods benefit from intravenous contrast agent administration.

CONCLUSIONS

Childhood liver tumors show a broad spectrum of morphological manifestations. Some entities can be characterized using standard imaging, some require multimodal imaging or histological assessment. In addition to morphological imaging criteria, age and the medical history as well as laboratory data play an important role in establishing the correct diagnosis.

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.

Biliary Rhabdomyosarcoma in an Infant Male With Neurofibromatosis Type 1

Different types of malignancies can be seen in patients with neurofibromatosis type 1 (NF-1). Herein we present a rare combination of NF-1 and biliary rhabdomyosarcoma in a male infant. An 11-month-old boy, who was recently diagnosed with NF-1, presented to the outpatient clinic with a 3-month history of prolonged jaundice, and failure to thrive. Clinical examination showed >20 café au let spots distributed mainly over the abdominal trunk. Hepatomegaly (4 cm below the costal margin) was additionally observed. His father was diagnosed with NF-1. Radiologic imaging studies showed a 6×5×5 cm in diameter cystic mass with multiple septations in the segment 4A of the liver. Surgical excision of the left hepatic lobe followed by hepatojejunostomy was further performed. Histopathology examination showed embryonal type rhabdomyosarcoma originating from the biliary duct. Chemotherapy regimen consisting of cyclophosphamide, actinomycin D, and vincristine, and radiotherapy were then initiated. This treatment led to a significant improvement in the patient's clinical status, and radiologic finding portrayed attainment of complete resolution. He is still in complete remission without any sequelae for 8 years.

Ex vivo liver resection and autotransplantation with cardiopulmonary bypass for hepatoblastoma in children: A case report

Some primary and secondary liver carcinomas cannot be resected using a conventional approach due to their size, location, or major vascular invasion. The aim of this study was to explore the application of ex vivo liver resection and autotransplantation for complicated HB in children. A 1.5-year-old girl with HB after repeated chemotherapy was analyzed. In this patient, tumor invasion includes the IV, V, and VIII liver segments, and thrombosis formed in the inferior vena cava and right atrium. It is difficult to obtain complete tumor resection using conventional hepatectomy. The patient was treated via ex vivo liver resection and autotransplantation, and tumor thrombus in the inferior vena cava and right atrium was removed via cardiopulmonary bypass. Operative methods and precautions were analyzed during and after the operation. The operation was completed successfully within 8 hours, and the liver's cold ischemia time was 190 minutes. The patient recuperated successfully, and the liver's function and AFP levels gradually tended to normalize 2 weeks after the operation. Ultrasonic examination revealed that the blood flow velocity of the hepatic vein, portal vein, and hepatic artery was good. The patient recovered and was discharged 3 weeks after the operation. Ex vivo liver resection and autotransplantation have great application value for complicated HB in children that is not suitable for conventional hepatic lobectomy.

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.

Applications of contrast-enhanced ultrasound in the pediatric abdomen

Contrast-enhanced ultrasound (CEUS) is a radiation-free, safe, and in specific clinical settings, highly sensitive imaging modality. Over the recent decades, there is cumulating experience and a large volume of published safety and efficacy data on pediatric CEUS applications. Many of these applications have been directly translated from adults, while others are unique to the pediatric population. The most frequently reported intravenous abdominal applications of CEUS in children are the characterization of focal liver lesions, monitoring of solid abdominal tumor response to treatment, and the evaluation of intra-abdominal parenchymal injuries in selected cases of blunt abdominal trauma. The intravesical CEUS application, namely contrast-enhanced voiding urosonography (ceVUS), is a well-established, pediatric-specific imaging technique entailing the intravesical administration of ultrasound contrast agents for detection and grading of vesicoureteral reflux. In Europe, all pediatric CEUS applications remain off-label. In 2016, the United States Food and Drug Administration (FDA) approved the most commonly used worldwide second-generation ultrasound contrast SonoVue®/Lumason® for pediatric liver and intravesical applications, giving new impetus to pediatric CEUS worldwide.