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CLASSIFICATION

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  • Polyclonal lymphocyte and plasma cell disorders can be classified into two major groups (Table 49–1):

    — Primary disorders that result from defects intrinsic to B lymphocytes (e.g., X-linked agammaglobulinemia), T lymphocytes (e.g., congenital thymic aplasia), and/or natural killer cells, the latter usually coupled with a B or T cell deficiency (e.g., interleukin (IL)-7 receptor α-chain deficiency) (see Chap. 51).

    — Acquired disorders that result from physiologic or pathophysiologic responses to extrinsic factors, usually infectious agents (e.g., Epstein-Barr virus or human immunodeficiency virus infection). (See Chaps. 50, 52, 53.)

  • The monoclonal lymphoid disorders are classified in Chap. 54 and individual neoplastic lymphoid diseases are described in Chaps. 5572.

    — Disparate disorders can have similar clinical manifestations, such as recurrent infections as a result of either B or T cell deficiency.

  • Lymphocyte disorders can have clinical manifestations that are not restricted to cells of the immune system (e.g., leprosy or systemic lupus erythematosus).

  • In some cases, classification is influenced by disease manifestations:

    — Diseases caused by production of pathologic autoantibodies; e.g., autoimmune hemolytic disease (see Chaps. 2426), autoimmune thrombocytopenia (see Chap. 120), and systemic autoimmune diseases (e.g., myasthenia gravis).

    — Diseases caused by excess production of lymphocyte cytokines; e.g., chronic inflammatory disorders.

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Table Graphic Jump Location
TABLE 49–1CLASSIFICATION OF NON-CLONAL DISORDERS OF LYMPHOCYTES AND PLASMA CELLS

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