HMGA2 and yolk sac tumor: For example, the HMGA2 positivity rate was markedly higher in papillary carcinomas of the kidney (61.7%) than in clear cell (7.2%) and in chromophobe cancers (7.8%), and in yolk sac tumors (95.6%) or embryonal carcinomas (73.5% positive) than in seminomas (18.7% positive) of the testis.