Fine needle aspiration biopsy cytology of hepatoblastoma.

Fine needle aspiration biopsy (FNAB) from four patients with histologically proven hepatoblastoma (HB) is reviewed. Patient ages ranged from 5 mo to 19 mo; two were male and two were female. Initial cytologic diagnoses were hepatoblastoma in two cases, malignant neoplasm consistent with liver cell tumor in one case, and probable Wilm's tumor in a fourth case. Cytologic features were similar in all cases and included highly cellular smears composed of a uniform population of small to intermediate sized round to oval cells. Extramedullary hematopoietic cells were obvious in smears of one patient. Neither bile nor extracellular stroma was seen. Immunohistochemical stains performed in two cases demonstrated positive staining for low-molecular-weight cytokeratins expressing polypeptides 8 and 18 of the Moll classification. Staining for vimentin, carcinoembryonic antigen, and epithelial membrane antigen was negative. alpha-Fetoprotein and alpha 1-antitrypsin stains were equivocal because of high background staining. Electron microscopy from three cases showed cells with features of immature hepatocytes. Three tumors were subsequently examined histologically by surgical biopsy, and one at autopsy. All were epithelial-type HB containing a mixture of "fetal" and "embryonal" hepatocytes. These results demonstrate the successful mimicry of FNAB cytology of hepatoblastoma to its histologic counterpart and its clinical utility in the diagnosis of intrahepatic masses of children.