[Methotrexate-associated lymphoproliferative disorders: clinical aspects].

Methotrexate-associated lymphoproliferative disorders (MTX-LPD) is categorized into other iatrogenic immunodeficiency-associated lymphoproliferative disorders, developing LPD in patients with autoimmune diseases (AIDs) under low dose MTX administration. Two-thirds of MTX-LPDs regresses after MTX withdrawal with the higher incidence in Japanese patients, MTX-LPDs consist of various subtypes of LPDs, the feature of each LPD such as the regressive rate, relapse/regrowth rate, and prognosis, widely varies. The absolute lymphocyte count (ALC) in peripheral blood is suggested to influence LPD development, regression, and relapse/regrowth events. Because various factors might effect the pathogenesis and clinical features of MTX-LPD, careful attention should be paid to assess MTX-LPD.