Concept
Lymphoproliferative disorders (LPDs) refer to a specific class of diagnoses, comprising a group of several conditions, in which lymphocytes are produced in excessive quantities. These disorders primarily present in patients who have a compromised immune system. Due to this factor, there are instances of these conditions being equated with "immunoproliferative disorders"; although, in terms of nomenclature, lymphoproliferative disorders are a subclass of immunoproliferative disorders—along with hypergammaglobulinemia and paraproteinemias. Follicular lymphoma chronic lymphocytic leukemia acute lymphoblastic leukemia hairy cell leukemia Hemophagocytic lymphohistiocytosis (HLH) B-cell lymphomas T-cell lymphomas multiple myeloma Waldenström's macroglobulinemia Wiskott–Aldrich syndrome Langerhans cell histiocytosis (LCH) Lymphocyte-variant hypereosinophilia Pityriasis Lichenoides (PL, PLC, PLVA) post-transplant lymphoproliferative disorder autoimmune lymphoproliferative syndrome (ALPS) "Lymphoid interstitial pneumonia" Epstein–Barr virus-associated lymphoproliferative diseases Castleman disease X-linked lymphoproliferative disease Lymphoproliferative disorders are a set of disorders characterized by the abnormal proliferation of lymphocytes into a monoclonal lymphocytosis. The two major types of lymphocytes are B cells and T cells, which are derived from pluripotent hematopoietic stem cells in the bone marrow. Individuals who have some sort of dysfunction with their immune system are susceptible to develop a lymphoproliferative disorder because when any of the numerous control points of the immune system become dysfunctional, immunodeficiency or deregulation of lymphocytes is more likely to occur. There are several inherited gene mutations that have been identified to cause lymphoproliferative disorders; however, there are also acquired and iatrogenic causes. X-linked lymphoproliferative disease A mutation on the X chromosome is associated with a T cell and natural killer cell lymphoproliferative disorder.