Hematology Meeting Reports 2009;3(1):115–122 | 115 | T-cell acute lymphoblastic leukemia (T-ALL) and T-cell lym- phoblastic lymphoma (T-LBL) derive from malignant transforma- tion of T-cell precursors at various levels of differentiation. They are quite rare diseases in adults, accounting for 20-25% of acute lymphoblastic leukemia (ALL) and 1-2% of all non-hodgkin lym- phomas (NHL) respectively. Although originally recognised and treated as separate entities, it was subsequently accepted that T-ALL and T-LBL represent dif- ferent manifestations of the same underlying disease because of their morphological, immunophe- notypic and genetic similarities. However, differences in the clini- cal and biological behavior and distinct gene expression profile have been observed. 1,2 They are aggressive diseases, with an increased incidence in adolescents and young adults and male predominance. T-ALL patients have an extensive bone marrow infiltration and involvement of extranodal sites, in particular the mediastinum, is common. Traditionally, T-LBL is defined by the absence of, or minimal (<25%) bone marrow involvement, and the T-cell acute lymphoblastic leukemia and T-cell lymphoblastic lymphoma: therapy in adults A B S T R A C T T-cell acute lymphoblastic leukemia (T-ALL) and T-cell lymphoblastic lym- phoma (T-LBL) are aggressive neoplasms derived from malignant transforma- tion of lymphoblasts committed to T-cell lineage. Because of their morpholog- ical, immunophenotypic and clinical similarities, they have often been thought to represent a spectrum of a single disease, and the distinction between them had sometimes been arbitrary. Following the pediatric experience, the main cur- rent therapies for both T-ALL and T-LBL in adults are based on intensive induc- tion chemotherapy, including central nervous system prophylaxis, and a pro- longed maintenance phase. Despite complete remission rates up to 80-90%, similar to those obtained in children, the prognosis in adults is less favourable, mainly because of high rates of relapse. A convincing prognostic model to determine which patients have to be offered more intensive consolidation, such as stem cell transplantation, is lacking. However, recent biological studies pro- vided the evidence for a number of differences in the molecular and genetic pro- files between T-ALL with different outcome and between T-ALL versus T-LBL. The precise definition of the aberrant molecular pathways relevant for the patho- genesis of neoplastic cells as well as the possibility to accurately evaluate the treatment response by minimal residual disease studies will probably be worth- while in defining more precise prognostic models and in developing new target therapies. M. Bonifacio O. Perbellini G. Pizzolo Department of Clinical and Experimental Medicine, Section of Hematology, University of Verona, Italy SESSION VII