The role of diagnostic imaging and liver biopsy in the diagnosis of focal nodular hyperplasia in children

Congenital focal nodular hyperplasia-like lesion mimicking hepatoblastoma: anecdotal but plausible

Focal nodular hyperplasia (FNH)-like lesions of the liver are rare in the pediatric population and are seldom reported as congenital lesions. The differential diagnosis between these lesions and pure-fetal hepatoblastoma (HBL) is challenging. We present a case of a congenital FNH-like hepatic lesion, managed with a right hepatectomy due to suspected fetal HBL. Additionally, a review of all published cases of congenital FNH-like lesions of the liver was carried out.MRI.

Focal Nodular Hyperplasia-Like Lesions With Glypican-3 Positivity in Infancy

PURPOSE AND CONTEXT

Glypican-3 is often used to discriminate between neoplastic and nonneoplastic liver. In focal lesions, positivity may be considered suggestive of a malignancy such as hepatoblastoma. However, glypican-3 is also normally expressed in the immature liver. We present a series of 5 cases of focal nodular hyperplasia (FNH)-like lesions arising in very young patients with glypican-3 expression and highlight the challenges these lesions present in the differential diagnosis of hepatoblastoma.

METHODS

Cases were obtained from the files of 3 tertiary pediatric hospitals. Clinical data were obtained from the electronic medical record and histopathologic material including immunohistochemical stains were reviewed.

KEY RESULTS

Patients were aged 2 weeks to 6 months with peak AFP levels ranging from 88.6 to 204,696 ng/mL. Microscopically, all were variably demarcated hepatocellular lesions with cords of hepatocytes, marked sinusoidal dilatation, and occasional fibrous bands and areas reminiscent of central scar with bile ducts. No significant cytologic atypia or increased mitotic activity were present. All showed glypican-3 expression and were negative for nuclear beta-catenin with intact reticulin framework.

CONCLUSIONS

Our study highlights the pitfalls of evaluating focal liver lesions in infants when high AFP levels and glypican-3 expression may reflect immaturity rather than neoplasia.

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.

Liver Tumors in Pediatric Patients

The most recent advance in the care of children diagnosed with hepatoblastoma and hepatocellular carcinoma is the Pediatric Hepatic International Tumor Trial, which opened to international enrollment in 2018. It is being conducted as a collaborative effort by the pediatric multicenter trial groups in North America, Europe, and the Far East. This international effort was catalyzed by a new unified global risk stratification system for hepatoblastoma, an international histopathologic consensus classification for pediatric liver tumors, and a revised 2017 collaborative update of the PRE-Treatment EXTent of disease radiographic based staging system.

Can diffusion-weighted imaging distinguish between benign and malignant pediatric liver tumors?

BACKGROUND

There are limited data on utility of diffusion-weighted imaging (DWI) in the evaluation of pediatric liver lesions.

OBJECTIVE

To determine whether qualitative and quantitative DWI can be used to differentiate benign and malignant pediatric liver lesions.

MATERIALS AND METHODS

We retrospectively reviewed MRIs in children with focal liver lesions to qualitatively evaluate lesions noting diffusion restriction, T2 shine-through, increased diffusion, hypointensity on DWI and apparent diffusion coefficient (ADC) maps, and intermediate signal on both, and to measure ADC values. Pathology confirmation or a combination of clinical, laboratory and imaging features, and follow-up was used to determine final diagnosis.

RESULTS

We included 112 focal hepatic lesions in 89 children (median age 11.5 years, 51 female), of which 92 lesions were benign and 20 malignant. Interobserver agreement was almost perfect for both qualitative (kappa 0.8735) and quantitative (intraclass correlation coefficient [ICC] 0.96) diffusion assessment. All malignant lesions showed diffusion restriction. Most benign lesions other than abscesses were not restricted. There was significant association of qualitative restriction with malignancy and non-restriction with benignancy (Fisher exact test P<0.0001). Mean normalized ADC values of malignant lesions (1.23x10^-3 mm²/s) were lower than benign lesions (1.62x10^-3 mm²/s; Student's t-test, P<0.015). However, there was significant overlap of ADC between benign and malignant lesions, with wide range for each diagnosis. Receiver operating characteristic (ROC) analysis revealed an area under the curve (AUC) of 0.63 for predicting malignancy using an ADC cut-off value of ≤1.20x10^-3 mm²/s, yielding a sensitivity of 78% and a specificity of 54% for differentiating malignant from benign lesions.

CONCLUSION

Qualitative diffusion restriction in pediatric liver lesions is a good predictor of malignancy and can help to differentiate between benign and malignant lesions, in conjunction with conventional MR sequences. Even though malignant lesions demonstrated significantly lower ADC values than benign lesions, the use of quantitative diffusion remains limited in its utility for distinguishing them because of the significant overlap and wide ranges of ADC values.

Clinical Features of Focal Nodular Hyperplasia of the Liver in Children

BACKGROUND

Focal nodular hyperplasia (FNH) is a benign hepatic lesion that is rare in children. The aim of the present study was to review the clinical features of children with FNH and our institution's experience in the management of this rare disease.

METHODS

A review of the medical records of children diagnosed as having FNH between 1999 and 2013 at West China Hospital of Sichuan University was undertaken.

RESULTS

Seventy-nine patients with FNH were identified: 68 patients without a history of malignancy and 11 patients with a history of malignancy. Thirty-seven (46.8%) patients were symptomatic at presentation. Patients with a history of malignancy had smaller FNH lesions and were less likely to have a central scar in FNH than do patients without a history of malignancy. Forty-seven patients underwent liver resection because of concern for malignancy, symptoms, and/or large lesions. Three patients were treated by embolization because of compression of the adjacent organs. There was no operative death or severe postoperative complications. Fourteen patients underwent liver biopsy to rule out malignant masses. The remaining 15 patients were managed expectantly with imaging surveillance. On follow-up, 2 patients for whom observation was initially recommended eventually required resection because of a mass effect.

CONCLUSIONS

The clinical features of pediatric FNH are variable and can be nonspecific. Our data emphasize the therapeutic approach that active management is indicated in symptomatic or progressive FNH and in children with diagnostic difficulties, whereas observation management is recommended in asymptomatic children with a definitive diagnosis.

Hepatocellular Carcinoma, Fibrolamellar Variant: Diagnostic Pathologic Criteria and Molecular Pathology Update. A Primer

Fibrolamellar hepatocellular carcinoma (FL-HCC) is generally a fairly rare event in routine pathology practice. This variant of hepatocellular carcinoma (HCC) is peculiarly intriguing and,in addition, poorly understood. Young people or children are often the target individuals with this type of cancer. Previously, I highlighted some pathology aspects of FL-HCC, but in this review, the distinctive clinico-pathologic features of FL-HCC and the diagnostic pathologic criteria of FL-HCC are fractionally reviewed and expanded upon. Further, molecular genetics update data with reference to this specific tumor are particularly highlighted as a primer for general pathologists and pediatric histopathologists. FL-HCC may present with metastases, and regional lymph nodes may be sites of metastatic spread. However, peritoneal and pulmonary metastatic foci have also been reported. To the best of our knowledge, FL-HCC was initially considered having an indolent course, but survival outcomes have recently been updated reconsidering the prognosis of this tumor. Patients seem to respond well to surgical resection, but recurrences are common. Thus, alternative therapies, such as chemotherapy and radiation, are ongoing. Overall, it seems that this aspect has not been well-studied for this variant of HCC and should be considered as target for future clinical trials. Remarkably, FL-HCC data seem to point to a liver neoplasm of uncertain origin and unveiled outcome. A functional chimeric transcript incorporating DNAJB1 and PRKACA was recently added to FL-HCC. This sensational result may give remarkable insights into the understanding of this rare disease and potentially provide the basis for its specific diagnostic marker. Detection of DNAJB1-PRKACA seems to be, indeed, a very sensitive and specific finding in supporting the diagnosis of FL-HCC. In a quite diffuse opinion, prognosis of this tumor should be reconsidered following the potentially mandatory application of new molecular biological tools.

Pediatric multifocal liver lesions evaluated by MRI

Objective:

The purpose of this study is to present our experience with MRI evaluation of multifocal liver lesions in children and describe the MRI characteristics of these lesions.

Patients and Methods:

A retrospective review of consecutive MRI exams performed for the evaluation of multiple liver lesions between 1 January 2007 and 31 December 2012 was done to note the number of lesions, the size of the largest lesion, MR signal characteristics, and background liver. Final diagnosis was assigned to each case based on pathology in the available cases and a combination of clinical features, imaging features, and follow-up in the remaining cases.

Results:

A total of 48 children (22 boys, 26 girls; age between 3 months and 18 years with average age 10.58 years and median age 11 years) were included in the study. Totally 51 lesion diagnoses were seen in 48 children that included 17 focal nodular hyperplasia (FNH), 8 hemangiomas, 7 metastases, 6 regenerative nodules, 3 adenomas, 3 abscesses, and one each of angiomyolipoma, epithelioid hemangioendothelioma, focal fatty infiltration, hepatocellular carcinoma, hepatic infarction, nodular regenerative hyperplasia, and hepatic cyst. Background liver was normal in 33, cirrhotic in 10, fatty in 3, and siderotic in 2 children. Most FNH, hemangiomas, and regenerative nodules showed characteristic MRI features, while metastases were variable in signal pattern.

Conclusion:

Many commonly seen multifocal liver lesions in children have characteristic MRI features. MRI can help to arrive at reasonable differential diagnoses for multifocal liver lesions in children and guide further investigation and management.

Focal nodular hyperplasia in children: an institutional experience with review of the literature

BACKGROUND

Focal nodular hyperplasia (FNH) is uncommonly diagnosed in pediatric patients and may be difficult to distinguish from a malignancy. We present a review of all children with a tissue diagnosis of FNH at our institution, describe the diagnostic modalities, and provide recommendations for diagnosis and follow-up based on our experience and review of the literature.

METHODS

A retrospective review of children <18years of age diagnosed with FNH at a single institution was performed from 2000 to 2013.

RESULTS

Twelve patients were identified with a tissue diagnosis of FNH. Two patients required surgical resection of their lesion owing to concern for malignancy. Ten patients were managed expectantly with imaging surveillance after biopsy confirmed a diagnosis of FNH. All patients who underwent MRI had very typical findings including hypointensity on T1 weighted sequences, hyperintensity on T2, and homogenous uptake of contrast on the arterial phase. On follow-up all patients had either a stable lesion or reduction in size.

CONCLUSIONS

Focal nodular hyperplasia presents typically in children with liver disease, have undergone chemotherapy, and adolescent females. Young children, particularly <5years of age, without underlying liver disease or history of chemotherapy can pose a diagnostic dilemma. In this unique subgroup of children with FNH, MRI and/or needle biopsy should be adequate diagnostic modalities for these lesions.

Focal nodular hyperplasia of the liver: an emerging complication of hematopoietic SCT in children

Hepatic focal nodular hyperplasia (FNH) is a nonmalignant condition rarely affecting children previously treated for cancer, especially those who received hematopoietic SCT (HSCT). Some aspects of its pathogenesis still remain unclear and a strong association with specific risk factors has not yet been identified. We report here a single institution's case series of 17 patients who underwent HSCT and were diagnosed with FNH, analyzing retrospectively their clinical features and the radiological appearance of their hepatic lesions. We aimed to compare the diagnostic accuracy of ultrasound (US) and magnetic resonance imaging (MRI) and to explore the role of transient elastography (FibroScan) to evaluate the degree of hepatic fibrosis in FNH patients. Our analysis showed an association of FNH with age at transplant ⩽12 years (hazard ratio (HR) 9.10); chronic GVHD (HR 2.99); hormone-replacement therapy (HR 4.02) and abdominal radiotherapy (HR 4.37). MRI proved to be a more accurate diagnostic tool compared with US. Nine out of 12 patients who underwent FibroScan showed hepatic fibrosis. Our study points out that FNH is an emerging complication of HSCT, which requires a lifelong surveillance to follow its course in cancer patients.

Gadobenate-dimeglumine-enhanced magnetic resonance imaging for hepatic lesions in children

BACKGROUND

Magnetic resonance imaging enhanced by hepatocyte-specific contrast media has been found useful to characterize liver lesions in adults and children.

OBJECTIVE

To present our experience with gadobenate dimeglumine (Gd-BOPTA)-enhanced MRI for evaluation of focal liver lesions in children.

MATERIALS AND METHODS

We retrospectively reviewed gadobenate-dimeglumine-enhanced MR images obtained for evaluation of suspected hepatic lesions in 30 children. Signal characteristics on various sequences including 45- to 60-min hepatobiliary phase images were noted by two radiologists. Chart review identified relevant clinical details including history of cancer treatment, available pathology and stability of lesion size on follow-up imaging.

RESULTS

Of the 30 children who had gadobenate-enhanced MRI, 26 showed focal lesions. Diagnoses in 26 children were focal nodular hyperplasia (FNH) in 15, hemangiomas in 3, regenerating nodules in 3, focal fatty infiltration in 2, indeterminate lesions in 3, and one patient each with adenomas, hepatoblastoma and metastasis. Two patients had multiple diagnoses. All FNH lesions (39), all regenerative nodules (19) and an indeterminate lesion were iso- or hyperintense on hepatobiliary-phase images while all other lesions (28) were hypointense to hepatic parenchyma. The average follow-up period was 21.7 months.

CONCLUSION

Our experience with gadobenate-enhanced MRI indicates potential utility of gadobenate in the evaluation of pediatric hepatic lesions in differentiating FNH and regenerating nodules from other lesions.