Immunohistochemistry demonstrated a CLL/SLL phenotype with positivity for CD20 (a B-cell marker), co-expression of dim CD5 (a T-cell marker) (Figure 1C, 1E), and absence of cyclin-D1 (a protein required in cell cycle G1/S transition) expression (Figure 1F). The lymphoma cells did not express CD10 (a surface glycoprotein), BCL-6 (a transcription repressor), or CD43 (surface glycoprotein). The background T-cells were highlighted by CD3 ( cluster of differentiation 3 protein complex) (Figure 1D) and showed equal expression of CD5. This evidence concerns the gene CD5 and B-cell chronic lymphocytic leukemia.