CD34 IMMUNOREACTIVITY IN HEPATOBLASTOMA

Sinusoids are seen not only in the normal liver but also in hepatoblas toma, a tumor that exhibits a wide spectrum of different epithelial an d mesenchymal lines of differentiation, on which classification into d ifferent subtypes is based. In this study, sinusoids in 12 hepatoblast omas of various subtypes and normal liver were investigated with an an tibody against CD34 to detect differences of possible diagnostic signi ficance. In contrast to sinusoids in the normal liver, where only foca l staining in the vicinity of the portal tracts was observed, sinusoid s in hepatoblastoma exhibited strong continuous staining for CD34. In fetal hepatoblastoma the sinusoids were arranged in a fine network res embling that seen in the normal liver, Embryonal hepatoblastoma exhibi ted fewer sinusoids and these were less regularly orientated, Only a f ew sinusoids were seen in the two small cell hepatoblastomas investiga ted. One of these tumors exhibited strong staining of the tumor cells, in addition to endothelial staining, for CD34, The marked differences in the sinusoidal expression of CD34 between normal liver and hepatob lastoma could be of value for distinguishing between highly differenti ated fetal hepatoblastoma and non-neoplastic liver tissue in surgical specimens. Our findings show that not only acute leukemias, but also s mall cell hepatoblastoma should be considered in the differential diag nosis of CD34-immunoreactive small round and blue cell tumors in child hood.