Yolk Sac Tumor : Cytokeratin AE1/AE3
Immunohistochemical profile of Yolk Sac Tumor (YST): Both glypican 3 and AFP are useful diagnostic markers of yolk sac tumor; however, Glypican 3 is more sensitive than AFP (100% +ve vs 80% +ve). Other positive markers include KIT, SALL4, cytokeratin AE1/AE3, and CAM5.2. GATA-4, a transcription factor, is expressed in pediatric cases. Important negative markers include CD30 and OCT3/4. A combination of SALL4 positivity and OCT3/4 negativity is considered to be highly specific for yolk sac tumor. The image shows strong immunoreactivity for cytokeratin AE1/AE3 in a yolk sac tumor.