Figure 2

Conventional HE-staining demonstrated areas of embryonic (a) and fetal (b) hepatoblastic cells, which were positive for HepPar-1 (c). Of note, the tumor cells in the necrotic tumor portions were also focally still HepPar-1 positive (d). Other tumor areas showed tumor cells embedded into a fibrillar matrix (e) and revealed a strong positivity for synaptophysin (f) as well as partly S-100 protein (g). In other areas a rhabdomyosarcomatous tumor cell differentiation (h; insert showing focally visible cross-striation) with expression of myogenin (i), desmin (j) as well as sarcomer actin (k) was visible. Cytokeratin 5/6 expression was restricted to small foci of squameous differentiation (l). Areas of cystic epithelial differentiation (m) showed positivity for cytokeratins 7 (n) and 19 (o). Focally, osteoid formation was observed (p). (a,b,e,h,m,p: hematoxylin eosin; c,d,g,h,i-l,n,o: immunostainings with antibodies as indicated). (magnification bars a,b,i: 50 μm; c-h,j-p: 100 μm; l: 300 μm)