CD4 and primary cutaneous T-cell non-Hodgkin lymphoma: Finally, the immunodeficiency in late stage CTCL could also caused by a gradual displacement of non-malignant T cells by the expanding malignant T cell clones; in other words, that the malignant T cells eventually outcompete and substitute the non-malignant T cell population, which results in a state reminiscent of advanced AIDS with a lack of functional CD4 T helper cells and severe immunosuppression [1,2,10,52].