Hepatoblastoma--an attempt of histological subtyping on fine-needle aspiration material

Hepatoblastoma (HB) is classified into epithelial, mixed (epithelial/mesenchymal), and small-cell (anaplastic) type. Wnt/β-catenin pathway plays a key role in hepatic development, regeneration, and tumorigenesis, and HB is known to present β-catenin mutations (50-90%). The present study was undertaken to delineate the cytomorphologic features of HB and to evaluate the feasibility of subtyping of HB on fine-needle aspiration cytology (FNAC). The expression of β-catenin in these tumors was also evaluated both of histopathologic sections and on the aspirated material. Thirty-three cases with fine-needle aspirates of HB were retrieved over a period of 12 years. Cytologic diagnosis was reviewed in the light of clinicoradiological data, response to therapy, and subsequent histopathology. Immunochemistry for β-catenin was performed in 19 of 33 cases on histopathologic sections (n = 10)/cell blocks (n = 6)/cytosmears (n = 3). Based on the cytologic features, the cases were divided into fetal HB (n = 17), embryonal HB (n = 4), combined epithelial HB (n = 8), and mixed HB (n = 4). Four cases of histopathologically proven mixed HB were reported as pure epithelial HB on FNAC, as mesenchymal elements were not represented in the cytology smears. Cytoplasmic as well as nuclear staining for β-catenin was noted in a total of 10 of 19 cases. FNAC can accurately categorize epithelial HB; however, in mixed type, the accuracy depends on number of areas sampled. Cell block can be of help to perform ancillary investigations especially β-catenin for both diagnostic and therapeutic purposes.