Figure 12c. Mixed GCT (combined seminoma and choriocarcinoma) of the testis in a 31-year-old man with an enlarged testis containing a palpable mass. (a) Coronal T2-weighted MR image shows a smoothly marginated, rounded tumor. Although the upper part of the tumor appears homogeneously solid, the lower part is cystic. (b) Coronal contrast-enhanced T1-weighted MR image shows some fibrovascular septa (arrow), which are indicative of a seminoma. At pathologic analysis of the resected specimen, the upper part of the tumor was diagnosed as a seminoma. (c) Photomicrograph (original magnification, x400; H-E stain) of the lower part of the tumor shows both syncytiotrophoblasts (black arrow) and cytotrophoblasts (white arrow) with hemorrhage.