Comparison of key immunophenotypic markers (CD5, CD10, CD23, CD25, CD103, cyclin D1) to differentiate chronic lymphocytic leukemia (CLL), mantle cell lymphoma (MCL), follicular lymphoma (FL), hairy cell leukemia (HCL), and splenic diffuse red pulp lymphoma (SDRPL). The gene discussed is CCND1; the disease is hairy cell leukemia.