Cytogenetics as an aid in the diagnosis of lymphomas

Multiple classifications of lymphomas are available. Generally, distinctions are made to identify low, intermediate, and high-risk groups. Histopathologic differentiation is at times difficult. The revised European-American lymphoma classification (REAL) uses histology, clusters of differentiation markers, histochemistry, and cytogenetics for definitive identification. This work reviews the karyotypic and FISH (fluorescent in situ hybridization) findings in some common lymphomas. B-Cell lymphomas, which make up approximately 85-90% of lymphomas, are associated with cytogenetic changes of +12, 13q14, 14q32, 2p11, and 22q13. Translocations help to support the diagnosis of follicular cell lymphoma t(14;18),(q32;q21), mantle cell lymphoma t(11;14)(q13;q32), and Burkitt's lymphoma t(2;8),t(8;14) and t(8;22). T-Cell lymphomas may show changes in 14q11,7p or 7q. Many of the lymphomas are characterized by complex karyotypic changes. Specific FISH probes are useful in determining characteristic or identifying marker chromosomes. Cytogenetic and FISH studies aid in the diagnosis, correct classification, and evaluation of therapy for a variety of lymphomas.