Definition of Lymphomas and Lymphoproliferative Neoplasms
Lymphomas are malignant neoplasms originating from cells of the lymphatic and immune system, specifically B-lymphocytes, T-lymphocytes, or natural killer (NK) cells, while lymphoproliferative neoplasms encompass a broader category that includes both malignant lymphomas and other abnormal proliferations of lymphoid cells with varying degrees of malignant potential. 1
Core Definitions
Lymphomas
Lymphomas represent a heterogeneous group of lymphoproliferative disorders that originate primarily from B-cells (80-85% of cases in the United States), T-cells (15-20%), or NK cells (rare) within the lymphatic system 1
The majority of lymphomas arise from lymph nodes, though some originate in extranodal sites, and they constitute approximately 4-5% of newly diagnosed cancers 2, 1
Lymphomas are fundamentally neoplasms of the immune system that demonstrate surface and cytoplasmic antigenic phenotypes reflecting qualitative and quantitative alterations or aberrant expression of genetic material 3, 4
Lymphoproliferative Neoplasms - Broader Spectrum
Lymphoproliferative neoplasms include a wider spectrum beyond frank malignant lymphomas, encompassing proliferations with uncertain malignant potential and conditions arising from immune dysregulation 1
This broader category includes B-cell proliferations of uncertain malignant potential, such as lymphomatoid granulomatosis (grades 1,2, and 3) and post-transplant lymphoproliferative disease (PTLD) 1
Post-transplant lymphoproliferative disorders represent a distinct subset ranging from early reactive lesions (reactive plasmacytic hyperplasia, infectious mononucleosis-like) to polymorphic PTLD (polyclonal or monoclonal) to monomorphic PTLD that are classified according to standard lymphoma classifications 1
Classification Framework
WHO Classification Structure
The WHO classification divides lymphoid neoplasms into precursor neoplasms (precursor B-lymphoblastic leukemia/lymphoma and precursor T-lymphoblastic lymphoma/leukemia) and mature neoplasms (mature B-cell, T-cell, and NK-cell neoplasms) 1
Mature B-cell neoplasms include chronic lymphocytic leukemia/small lymphocytic lymphoma, follicular lymphoma, mantle cell lymphoma, diffuse large B-cell lymphoma, Burkitt's lymphoma, and various marginal zone lymphomas 1
Mature T-cell and NK-cell neoplasms include peripheral T-cell lymphomas, mycosis fungoides/Sézary syndrome, anaplastic large cell lymphoma, and extranodal NK/T-cell lymphoma 1
Key Distinguishing Features
Lymphoproliferative diseases demonstrate immune regulatory disorder phenotypes that can manifest as autoimmunity, hyperinflammation, immunodeficiency, or increased infection susceptibility, depending on the immune pathway most involved 5
These neoplasms may arise from immune deficiency or disordered regulation of the immune system, often associated with viral agents such as Epstein-Barr virus, human immunodeficiency virus, or human herpes virus 8 6
Immunophenotypic studies are essential for classification, as these disorders can be readily classified as T or B cell malignancies, with criteria evolved to differentiate neoplastic from reactive/physiologic expansions of lymphoid clones 3, 1
Clinical Context
Lymphoproliferative disorders represent a complex group of neoplasms accompanied by a broad range of immune regulatory disorder phenotypes, where immunological imbalance can play a role in lymphomagenesis and disease progression 5
The term encompasses conditions where neoplastic lymphoid proliferation may arise from primary immune disorders, with diffuse large B-cell lymphoma being the most commonly encountered neoplastic lesion, though Hodgkin lymphoma, Burkitt lymphoma, and peripheral T-cell lymphomas have also been documented 6