Rare subtype of hepatoblastoma in a young adult: difficulties in the histopathological differentiation from hepatocellular carcinoma

Abstract

Background: Hepatoblastoma is a primary malignant tumor of the liver usually occurring in children, whereas it is very rare in adults, affecting males slightly more. Case Presentation: We report a case of a 20-year old female patient with a palpable liver mass and significantly elevated alphafetoprotein (AFP), Serum Glutamic Oxaloacetic Transaminase, and Serum Glutamic-Pyruvic Transaminase values. The microscopic examination revealed a mixed cell population of small cells with an oval-shaped nucleus and scant relatively basophilic cytoplasm co-existing with larger cells with eosinophilic or clear cytoplasm, round nuclei, arranged in trabeculae of six or more cells separated by thin fibrous septa. The immunohistochemical assessment of the tumor cells revealed positivity for AFP, Glypican-3, Glutamate Synthetase, polyclonal Carcinoembryonic antigen, Cytokeratin (CK8/18), and Epithelial Specific Antigen/Ep-CAM, membranous and focally nuclear positivity for b-catenin, focal positivity for CK19 and vimentin and faintly focal positivity for Sallike protein-4 and Cluster Differentiation 99. The cell proliferation rate Ki-67 was high, at about 85% and concerning the prognostic markers, there was a positive expression of Cyclin D1 at approximately 80% of the tumor cells, whereas c-myc was negative. These findings drove us to the diagnosis of hepatoblastoma, macrotrabecular subtype. Conclusion: Although the age, medical history, clinical findings, and the laboratory investigations of the patient suggested hepatocellular carcinoma, on the histological examination the mixed blastematous morphology of the tumor combined with the results of the immunohistochemical assay, lead to the diagnosis of hepatoblastoma.

Adult hepatoblastoma: making the challenging distinction from hepatocellular carcinoma

“…3 An excess of seventy cases have so far been reported in English literature since the entity was first described by Bartok in 1958. 1 , 2 , 4 Males and females are equally affected with a median age of 39 to 42 years in systematic reviews. 5 , 6 Concrete risk factors for the occurrence of this malignancy in adults have yet to be identified, however, cases occurring in the setting of chronic viral hepatitis have been reported.…”

“…3 , 6 , 7 It is notable that adult HB shares greater histologic similarities with HCC in contrast to pediatric cases. 1 This morphologic diversity in the setting of non-specific clinical and radiologic manifestations make the distinction between HCC and adult HB rather challenging. Rougemont et al 8 delineated three main histologic criteria to distinguish HB from HCC, namely, presence of a “light and dark” pattern, extramedullary hematopoiesis and mesenchymal elements.…”

“…Although there exists not one particular marker to differentiate HB from HCC, 1 , 6 a roster of immunohistochemical stains may help evince the immature nature of this malignancy. In particular, epithelial and mesenchymal fetal components display nuclear and cytoplasmic expression for betacatenin and overexpress glutamine synthetase as a result of activation of the Wnt signaling pathway.…”

“…Cisplatin-based systemic chemotherapy regimens are likewise recommended but therapeutic response is extremely poor as most cases are advanced at presentation. 1 These tumors are known to portend a negative prognosis, especially with increasing age, with a median survival of 2 months and survival rates as low as 16.7% within a year of diagnosis for patients aged 45 years and older. 6 …”

“…Hepatoblastoma (HB) accounts for the vast majority of liver neoplasms in the pediatric population but is exceptionally rare in adults with 75 non-pediatric cases reported as of this writing. 1 , 2 Hepatocellular carcinoma (HCC), the most common primary hepatic malignancy in adulthood, is understandably the foremost differential diagnosis for rare adult HB, however, distinguishing between these two disease entities may prove difficult to the encountering pathologist. Given the non-specific clinical, radiologic and gross pathologic manifestations of this malignancy, the diagnosis of HB in adults greatly relies on the correlation of distinct morphologic features and an overall immunohistochemical profile that sets it apart from HCC.…”