Chromosome aberrations are regularly detected in most hematologic neoplasms and in various solid tumors and are often associated with distinct morphologic and immunophenotypic features of certain clinico-pathologic entities of tumors (1 –4 ). Detection of these chromosome abnormalitites provides the basis for a detailed diagnosis and for the genetic classification of tumors. Especially in leukemias and lymphomas, many primary chromosome aberrations are associated with the clinical course of the disease. Moreover, during tumor progression, additional chromosome aberrations occur. Therefore, cytogenetic findings are very helpful for predicting the prognosis and for choosing risk-adapted treatment strategies (5 ,6 ).