CD99 was the former marker for Ewings' sarcoma; however, it is also expressed in other tumors such as synovial sarcoma, Wilms' tumor, vascular malignancy, neuroendocrine tumors, and lymphoblastic lymphoma, and therefore nowadays is not considered a reliable marker of tumor origin [1, 7, 8]. The gene discussed is CD99; the disease is neuroendocrine neoplasm.