Hepatoblastoma in a 15-month-old male: cytomorphology, electron microscopy, and differential diagnosis.

The authors describe a case of hepatoblastoma in a 15-month-old male and discuss the differential diagnosis and electron microscopic features of small round cell tumors. The patient was found to have an enlarged liver and was admitted to the hospital for further investigation. Fine-needle aspiration of the liver revealed small. uniform cells with increased nuclear/cytoplasmic ratio and focal rosette formation. A diagnosis of small blue cell neoplasm favoring hepatoblastoma was made, but neuroblastoma could not be ruled out. Electron microscopic analysis performed on the liver aspirate showed features of hepatic differentiation as well as absence of neuroblastic differentiation. The diagnosis of hepatoblastoma was made. Serum alpha-fetoprotein level of 33,250 mg/L confirmed the diagnosis. Liver biopsy performed subsequently showed tumor cells arranged in nests, acini, and trabeculae with mitotic figures. Electron microscopy showed the same findings as described above. The patient underwent chemotherapy for 4 months and subsequently a partial liver resection was performed. This case illustrates the important role of electron microscopy in evaluating small round cell tumors in children.