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SUMMARY
This chapter outlines the category of preneoplastic and neoplastic lymphocyte and plasma cell disorders. It introduces a framework for evaluating neoplastic lymphocyte and plasma cell disorders, outlines clinical syndromes associated with such disorders, and guides the reader to the chapters in the text that discuss each of these disorders in greater detail. Chapter 78 outlines the diseases caused by nonneoplastic disorders of lymphocytes and plasma cells.
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Acronyms and Abbreviations
α/β TCR, T-cell-receptor genes encoding the α and β chains of the T-cell receptor (Chap. 76); ALK, gene encoding anaplastic lymphoma kinase; BCL2, gene encoding B-cell chronic lymphocytic leukemia (CLL)/lymphoma 2; BCL6, gene encoding B-cell chronic lymphocytic leukemia (CLL)/lymphoma 6; cIg, cytoplasmic immunoglobulin; EBER, Epstein-Barr-virus-encoded RNA; EBV, Epstein-Barr virus; γ/δ TCR, T-cell-receptor genes encoding the γ and δ chains of the T-cell receptor (Chap. 76); HL, Hodgkin lymphoma; HLA, human leukocyte antigen; HTLV-1, human T-cell leukemia virus type 1; HHV8, human herpes virus 8; Ig, immunoglobulin; IgR, immunoglobulin gene rearrangement (Chap. 75); IL, interleukin; MALT, mucosa-associated lymphoid tissue; MUM1, gene encoding multiple myeloma oncogene 1; neg., negative; NK cell, natural killer cell; NOS, not otherwise specified; NPM, gene encoding nucleophosmin; PAX5, paired box gene 5; POEMS, polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes; REAL, revised European-American lymphoma; R-S, Reed-Sternberg; sIg, surface immunoglobulin (Chap. 75); sIgD, surface immunoglobulin D; sIgM, surface immunoglobulin M; TAL1, gene encoding T-cell acute leukemia-1; TCR, T-cell receptor; TdT, terminal deoxynucleotidyl transferase; Th2, T-helper type 2; WHO, World Health Organization.
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Lymphocyte and plasma cell malignancies present a broad spectrum of different morphologic features and clinical syndromes (Table 90–1). Lymphocyte neoplasms can originate from cells that are at a stage prior to T- and B-lymphocyte differentiation from a primitive stem cell or from cells at stages of maturation after stem cell differentiation. Thus, acute lymphoblastic leukemias arise from an early lymphoid progenitor cell that may give rise to cells with either B- or T-cell phenotypes (Chap. 91). On the other hand, chronic lymphocytic leukemia arises from a more mature B-lymphocyte progenitor (Chap. 92) and myeloma from progenitors at even later stages of B-lymphocyte maturation (Chap. 107). Disorders of lymphoid progenitors may result in a broad spectrum of lymphocytic diseases such as B or T cell lymphomas (Chaps. 98 and Chap. 104), hairy cell leukemia (Chap. 93), prolymphocytic leukemia (Chap. 92), natural killer cell large granular lymphocytic leukemia (Chap. 94),1 myeloma, and plasmacytoma (Chap. 107). Hodgkin lymphoma also is derived from a neoplastic B cell that has highly mutated immunoglobulin genes that are no longer expressed as protein (Chap. 97).
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