RESUMEN
Translocation t(4;11)(q21;p15) is a rare recurrent change associated to T-cell acute leukemia. In most cases, this alteration appears as the only abnormality or as part of a simple karyotype. In this report, we present the first case of T acute lymphoblastic leukemia/lymphoma (T-ALL/LBL) with the unbalanced translocation der(11)t(4;11)(q21;p15) as part of a very complex karyotype with multiple chromosome abnormalities, most of them not previously described in the literature. FISH (fluorescence in situ hybridization) and spectral karyotype (HiSKY) analysis confirmed the presence of complex alterations. The patient, a 16-year-old male, showed poor response to treatment and short survival (11 months). A detailed review of previously reported cases with t(4;11)(q21;p15) is also provided. The description of this type of alterations may contribute to the identification of new molecular mechanism associated to neoplastic development.