Three equine cases of mixed hepatoblastoma with teratoid features.
Authors: Loynachan A T, Bolin D C, Hong C B, Poonacha K B
Journal: Veterinary pathology
Summary
# Editorial Summary: Hepatoblastoma in Thoroughbreds Hepatoblastoma—a rare embryonal liver tumour—was identified in three Thoroughbred cases at the University of Kentucky between 1997 and the time of publication, each presenting with distinct clinical manifestations ranging from a solitary fetal mass to a metastatic neonate with widespread involvement of skin, brain, meninges and bone. Histological examination revealed characteristic sheets and cords of fetal and embryonal epithelial cells interspersed with variable haemorrhage, necrosis, and notably, osteoid and bone formation (teratoid features), whilst immunohistochemical analysis demonstrated variable alpha-fetoprotein positivity, frequent vimentin expression, and occasional cytokeratin staining across all three cases. The presence of teratoid elements—bone and osteoid within hepatic tissue—distinguishes these cases from typical hepatoblastoma and suggests a more complex developmental origin. Whilst hepatoblastoma remains exceptionally rare in equine medicine and unlikely to present a diagnostic challenge for practitioners, awareness of this tumour's variable presentation (solitary lesions to metastatic disease) and the potential for alpha-fetoprotein elevation as a marker may prove valuable should similar cases arise. Further investigation into the aetiology and prevalence of this neoplasia in young horses would be warranted given the aggressive metastatic behaviour observed in one case.
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Practical Takeaways
- •Hepatoblastoma is a rare but documented neoplasm in young Thoroughbreds that should be considered in differential diagnoses for unexplained masses or metastatic disease in neonates and fetuses
- •Hepatoblastomas can present with minimal clinical signs and be discovered incidentally at necropsy, highlighting the importance of thorough post-mortem examination in young horses with sudden death
- •This case series documents a tumor type with limited prior equine literature, contributing to the knowledge base for pathological diagnosis in neonatal and fetal equine neoplasia
Key Findings
- •Three Thoroughbred cases of mixed hepatoblastoma with teratoid features were identified over a 10-year period at a single diagnostic center
- •Hepatoblastomas presented as solitary hepatic masses in a fetus, neonate, and neonate, with one case showing extensive metastases to skin, brain, meninges, and bone
- •Microscopically all cases contained fetal and embryonal epithelial cells with variable amounts of hemorrhage, necrosis, osteoid, and bone
- •Immunohistochemical staining showed variable alpha-fetoprotein positivity, frequent vimentin positivity, and occasional cytokeratin positivity across all cases