Iatrogenic lymphoproliferative disorders in non-transplantation settings

Iatrogenic immunodeficiency-associated lymphoproliferative disorders of B-cell type that develop in patients receiving immunosuppressive drugs other than in the post-transplant setting

In the current revised 4th edition of the World Health Organization (WHO) classification, ‘other iatrogenic immunodeficiency-associated lymphoproliferative disorders (Oii-LPDs)’ is listed in the last section in the chapter on immunodeficiency-associated lymphoproliferative disorders. Oii-LPDs cover a broad spectrum from benign lesions to lymphoma, and correspond to one of the subtypes in the WHO classification for immunocompetent patients.

The WHO classification does not clearly indicate the histological subtype of this disease category; however, the framework of subtype classification is similar to the classification of post-transplant lymphoproliferative disorders, and recent studies have attempted to subcategorize Oii-LPDs that fit this unique disease type. In this review, we provide an overview of B-cell-type Oii-LPDs regarding their histopathology and immunophenotype, genetics and clinical behaviors.

Immunosuppressive and immunomodulatory therapy-associated lymphoproliferative disorders

A variety of therapeutic agents may increase the risk of lymphoproliferative disorders/neoplasms. These include those agents used to treat other malignancies (i.e., cytotoxic chemotherapy) and those used to treat or prevent certain diseases (or graft rejection) that alter the immune system. This review is restricted to the secondary lymphoid disorders that are unrelated to primary DNA damage by cytotoxic chemotherapy, and thus will include discussions regarding post-transplant lymphoproliferative disorders and those lymphoproliferations associated with the therapy of autoimmune and other immune-mediated diseases. Three drugs, or classes of drugs, used in the treatment of autoimmune and other immune-mediated diseases are discussed in some detail. These include methotrexate, anti-metabolites (including thiopurines and mycophenolate mofetil), and immunomodulators. The appropriate recognition of these disorders is important in order to correctly classify and institute appropriate therapy, recognizing that reduced immunosuppression or withdrawal of therapy may be necessary, rather than treating as a malignant lymphoma.