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Classic seminomas with three or more mitotic figures per high power field were originally defined as anaplastic seminomas and were thought to pursue a more aggressive clinical course. Several studies have since shown that the so-called "anaplastic seminoma" does not behave any more aggressively than classic seminoma when matched stage by stage. However, a subset of seminomas do appear more anaplastic than classic cases. The tumor cells have abundant eosinophilic cytoplasm, pleomorphic hyperchromatic nuclei, one or more prominent nucleoli, and show brisk mitotic activity. Their morphologic features are intermediate between classic seminoma and embryonal carcinoma.