BACKGROUND: Chronic lymphocytic leukemia (CLL) usually expresses CD5 antigen. However, 7–20% of patients are CD5 negative. We report here a series of 19 CD5-negative B-CLL cases.

MATERIAL AND METHODS: We reviewed 19 consecutive CD5-negative B-CLL cases seen in our medical center from 2009 to 2015 and compared them with 105 CD5-positive B-CLL cases. The two groups were compared in terms of clinical parameters, laboratory parameters, and survival characteristics.

RESULTS: Lymphadenopathy was present in 31.5% of the CD5-negative group and 51.4% of the CD5-positive group (p=0.029). Splenomegaly was present in 42.1% of the CD5-negative group and 16.1% of the CD5-positive group (p=0.029). There was no difference between the groups in terms of Binet A, B, and C stages (p=0.118, p=0.051, and p=0.882, respectively). The median thrombocyte count was 144×109/L and 160×109/L in the CD5-negative and CD5-positive groups, respectively (p=0.044). There was no difference between the two groups in terms of median neutrophil count (p=0.169). The mean lymphocyte count was 43.2±4.0×10^9/L and 36.7±3.2×10^9/L in the CD5-negative and CD5-positive groups, respectively (p=0.001). There was no difference between the groups in terms of autoimmune hemolytic anemia and autoimmune thrombocytopenia. In five-year follow-up, 84.2% of CD5-negative patients and 90.5% of CD5-positive patients were alive (p=0.393).

CONCLUSIONS: We found more isolated splenomegaly, less lymphadenopathy, a higher lymphocyte count, and a lower thrombocyte count in the CD5-negative group. There was no difference between the groups in terms of clinical stage, autoimmune phenomena, hemoglobin and neutrophil count, and survival.

Keywords: Antigens, CD5, Leukemia, Lymphocytic, Chronic, B-Cell, Survival