Germ cell tumor differential diagnosis

• Cytoplasmic membrane immunoreactivity for placental alkaline phosphatase and CD117, with usual negativity for AE1/AE3 cytokeratins, is helpful in the diagnosis of germinoma.
• The recently described marker, OCT3/4, a nuclear transcription factor, is especially helpful in the differential of germinoma and embryonal carcinoma with other neoplasms.
• Yolk sac tumor continues to be confused occasionally with clear cell carcinoma of the ovary.