Tumors of the lymphatic system.

Lymphoid neoplasms remain a serious diagnostic and therapeutic problem in p resent-day hematology. This is objectively due, on the one side, to extreme ly complicated and ramified immune system, on the other, to variability whi ch characterizes all lymphoid neoplasms. Subjective reasons consist in nume rous attempts to classify tumors of hematopoietic system by isolated or var iable features including morphological and immunophenotypical ones. A new c lassification of lymphoid neoplasms is proposed. It is based on the latest achievement in histology, cytology, immunochemistry and cytogenetics, main principles of tumor progression. Short clinical characteristics of the noso logical unities included in the classification are provided.