The immunohistochemical profile was similar in the original metastasis and the two orthotopic tumors, and was characteristic of a yolk sac tumor with extensive expression of cytokeratine Cam5.2 (Figure 1A, g, h and i), but with only focal expression of EMA (Figure 1A, j, k and l) and patchy immunoreactivity for AFP (Figure 1A, m, n and o). This evidence concerns the gene AFP and yolk sac tumor.