CD34 and sarcoma: CD34 staining may be variable, however, diffuse positive staining of an undifferentiated GEJ tumor can be seen and can also result in misclassification.2 Notably, SALL4 staining is also often seen, which can result in the erroneous classification as a germ cell tumor.13,16 Given the undifferentiated nature of the tumor and the variable expression of some lineage markers, it is likely in the past that these tumors have been misclassified as hematolymphoid tumors, sarcomas, poorly differentiated carcinomas, vascular tumors, and germ cell tumors.