A 6-year-old patient was admitted to the Petrovsky National Research Center of Surgery in Moscow, diagnosed with hepatoblastoma (HB) of the right lobe of the liver and after undergoing 4 cycles of SIOPEL (super PLADO) pre-operative chemotherapy. An immunohistochemistry test, performed after liver resection, revealed a rare combination of mixed epithelial and mesenchymal hepatoblastoma and yolk sac tumor. The epithelial component of HB consisted of highly differentiated fetal cells, while the mesenchymal component consisted of osteoid. The morphological structure of the second lesion corresponded to yolk sac tumor. Both tumors had regressive changes conditioned by chemotherapy: these changes were most pronounced in HB. In the highly differentiated fetal component of HB it was possible to detect a weak focal perinuclear alpha-fetoprotein expression, HepPar expression, membranous expression of beta-catenin and diffuse glutamine synthetase expression. Mitotic figures were not determined. The node of the yolk sac tumor had the characteristic histological structure of an endodermal sinus tumor with a hepatoid component. In the main tumor node and its nodular elements in the fibrovascular stroma it was possible to identify alpha-fetoprotein expression, CD34, nuclear and cytoplasmic expression of beta-catenin, CDX2, as well as a rare expression of PLAP and multi-cytokeratin, and mitotic activity was high (21 in 10 high power fields, 400x magnification). In the existing literature available to us, there is only one observation of combined hepatoblastoma and yolk sac tumor. Parents patients agreed to use personal data, including the fotos, in research and publications.
Human yolk sac tumor serially transplanted in nude mice: Its morphologic and functional properties