A t(18;22)(q21;q11) involving IGL/BCL2, A Rare Event in Chronic Lymphocytic Leukemia

We report a 63-year-old male whose bone marrow morphology and flow cytometry showed evidence of B-Chronic Lymphocytic Leukemia (B-CLL). Chromosome analysis of the bone marrow showed an abnormal karyotype, described as 46,XY,t(18;22)(q21;q11.2)[19]/46,XY[1]. FISH analysis on interphase nuclei revealed an abnormal clone with loss of D13S319 (13q14.3) in 68.0% of the cells examined. Deletion of chromosome 13 is the most common cytogenetic abnormality identified in CLL (approximately 50% of CLL). Recent studies suggest that deletion of chromosome 13q14 in 65% or more nuclei by FISH is associated with an intermediate to unfavorable prognosis in CLL. The t(18;22)(q21;q11.2) present in this case, as well as the t(2;18)(p12;q21), are variants of the t(14;18)(q32;q21); all three are abnormalities in CLL. These abnormalities are found in less than 4% of CLL cases. They are usually present within the context of a complex karyotype in a subset of CLL, but can also be observed in cases of benign lymphocytosis. Herein, we report a t(18;22)(q21;q11.2) in a CLL patient as a sole cytogenetic abnormality by conventional cytogenetics, and with loss of 13q14.3, as determined by FISH. To the best of our knowledge, this is one of the few cases of its kind.