What is the pathophysiology of non-Hodgkin lymphoma (NHL)?

Updated: Feb 25, 2021
  • Author: Sanjay Vinjamaram, MD, MPH; Chief Editor: Emmanuel C Besa, MD  more...
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Answer

NHLs are tumors originating from lymphoid tissues, mainly of lymph nodes. Various neoplastic tumor cell lines correspond to each of the cellular components of antigen-stimulated lymphoid follicles.

NHL represents a progressive clonal expansion of B cells or T cells and/or NK cells arising from an accumulation of lesions affecting proto-oncogenes or tumor suppressor genes, resulting in cell immortalization. These oncogenes can be activated by chromosomal translocations (ie, the genetic hallmark of lymphoid malignancies), or tumor suppressor loci can be inactivated by chromosomal deletion or mutation. In addition, the genome of certain lymphoma subtypes can be altered with the introduction of exogenous genes by various oncogenic viruses. Several cytogenetic lesions are associated with specific NHLs, reflecting the presence of specific markers of diagnostic significance in subclassifying various NHL subtypes.

Almost 85% of NHLs are of B-cell origin; only 15% are derived from T/NK cells, and the small remainder stem from macrophages. These tumors are characterized by the level of differentiation, the size of the cell of origin, the origin cell's rate of proliferation, and the histologic pattern of growth.

For many of the B-cell NHL subtypes, the pattern of growth and cell size may be important determinants of tumor aggressiveness. Tumors that grow in a nodular pattern, which vaguely recapitulate normal B-cell lymphoid follicular structures, are generally less aggressive than lymphomas that proliferate in a diffuse pattern. Lymphomas of small lymphocytes generally have a more indolent course than those of large lymphocytes, which may have intermediate-grade or high-grade aggressiveness. However, some subtypes of high-grade lymphomas are characterized by small cell morphology.


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