Lymphoblastic lymphoma is a very aggressive form of non-Hodgkin lymphoma (NHL), which often occurs in young patients, but not exclusively. Lymphoblastic lymphoma is commonly associated with large mediastinal masses and has a high predilection for disseminating to bone marrow and the central nervous system (CNS), much like acute lymphocytic leukemia (ALL). Treatment is usually patterned after ALL. Intensive combination chemotherapy with CNS prophylaxis is the standard treatment of this aggressive histologic type of NHL. Radiation therapy is sometimes given to areas of bulky tumor masses. Since these forms of NHL tend to progress quickly, combination chemotherapy is instituted rapidly once the diagnosis has been confirmed. Careful review of the pathologic specimens, bone marrow aspirate and biopsy specimen, cerebrospinal fluid cytology, and lymphocyte marker constitute the most important aspects of the pretreatment staging workup. New treatment approaches are being developed by the national cooperative groups. Other approaches include the use of bone marrow transplantation for consolidation. (Refer to the PDQ summary on Adult Acute Lymphoblastic Leukemia Treatment for more information.)