The aggressive clinical courses of Hodgkin lymphoma primarily diagnosed as methotrexate-induced non-specific lymphoproliferative disorder in patients with rheumatoid arthritis.

Recently, attention has been focused on methotrexate-induced lymphoproliferative disease (MTX-LPD), and atypical phenotypes are occasionally documented. We encountered two patients with rheumatoid arthritis (RA) who were diagnosed with non-specific LPD (LPD-nos). Biopsy samples were not obtained during the initial examination when the LPD development was discovered, and the patients achieved a complete response after MTX cessation (case 1) or steroid pulse therapy (case 2). However, the tumors flared up 1.5 years later, and LPD-nos was determined following biopsies of the lymph node (LN, case 1) and liver (case 2). Prednisolone was subsequently administered instead of chemotherapy; however, multiple masses, including in the spine (case 1), and severe icterus with liver dysfunction (case 2) were exacerbated within a few months. Although the re-biopsy of LN proved the presence of HL and radiation followed by aggressive chemotherapy rescued the patient (case 1), the superficially accessible biopsy site was not found, and autopsy finally revealed HL (case 2). In both cases, the underlying pathogenesis along with the B symptoms and laboratory abnormalities suggested MTX-LPD, HL in particular. Therefore, even if the pathological diagnosis does not confirm the specific LPD subtype, the administration of aggressive chemotherapy should be considered if the LPD activity flares severely.