T cell specific marker CD3 staining and Lymph node flow cytometry. A. Low power view and B. high power view showing tumor cells had focal cytoplasmic CD3 staining (large arrows) in contrast to background small T lymphocytes with strong membrane CD3 staining (small arrows). C, D. Lymph node flow cytometry immunophenotyping showed 2 populations of cells, with normal lymphocytes (in red) and an abnormal population with high side scatter (in green) which show expression of CD4 and are negative for surface CD3. Cytoplasm CD3 was not done.