Tumor cells were commonly positive for TDT (21/26, 80.8%), CD3 (29/31, 93.5%), and CD7 (25/27, 92.6%), and they were variably positive for CD5 (16/24, 66.7%), CD99 (14/19, 73.7%), CD2 (12/18, 66.7%), and CD1a (13/21, 61.9%). This evidence concerns the gene CD99 and neoplasm.