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.