Germ cell tumors primarily arise in gonads and extragonadal germ cell tumors, an uncommon entity, originates usually along the midline. Here, we report the fifth example of intrarenal pure yolk sac tumor in a 1.5-year-old boy who presented with abdominal pain and underwent excision of the mass for suspected Wilms tumor. On histopathology and immunohistochemistry, a diagnosis of a yolk sac tumor was rendered. Postoperative serum alpha–fetoprotein levels were 21 000 ng/dl. The purpose of this report is to emphasize the importance of suspecting a germ cell tumor as one of the differential diagnoses of a suspected case of Wilms tumor and the significance of evaluating serum alpha–fetoprotein levels preoperatively.
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