ALK and adult T-cell leukemia/lymphoma: CCR4 is a chemokine receptor involved in T cell migration into the skin and is highly expressed on neoplastic T cells of CTCL (~62%) [175], ATLL (~90%) [176], and certain PTCL subtypes, including ALK-negative ALCL (~66.7%), PTCL-NOS (38%), and nTFHL-AI (34.8%) [177,178].