A Japanese case of chronic lymphocytic leukemia with t (1;6)

Chronic lymphocytic leukemia (CLL) is a mature B-cell neoplasm characterized by increased abnormal non-large CD5+CD20+CD23+ B cells in peripheral blood, bone marrow, and lymphoid organs [1,2]. CLL usually exhibits an indolent clinical course, but sometimes shows aggressive clinical course, including Richter’s transformation with poor outcome. Poor prognosis in CLL is associated with expression of CD38 or zeta-chain associated protein-70 (ZAP-70), mutations and/or expression of tumor protein p53 (TP53), and abnormal cytogenetics [3]. The majority of patients with CLL have chromosomal deletions or additions, but chromosomal translocations are rare, and if present, they are usually associated with the loci of immunoglobulin (IG) genes, 14q32, 2p13, or 22q11 [4]. Also, information on the roles of these translocations in clinical outcome or pathogenesis is extremely limited in CLL.There are only a few reports of translocation t(1;6) involving chromosome 6p25？~？23 in patients with CLL [5-9]. This type of translocation was observed in approximately 0.5% of patients with CLL in the Belgian databases [5]. These cases showed an aggressive clinical course. Furthermore, when treated with purine analogues, patients often develop Richter’s transformation. It has been suggested that a regulator of B-cell differentiation, interferon regulatory factor 4 (IRF4) gene on 6p25, correlates with the pathogenesis of CLL cases with t (1;6) [5].Here, we report the first Asian case of CLL with translocation t(1;6) where CLL cells expressed IRF4. The patient showed an aggressive clinical course and was successfully treated with conventional chemotherapy without purine analogue.A 56-year-old Japanese male, who had taken medical laboratory examinations every half-year, was first found to have a slightly elevated peripheral white blood cell count (12 x 109/L) in July 2010, while showing no other abnormal findings on blood examination and systemic positron emission tomography using 18？F-fluorodeox