Patients with rheumatoid arthritis often develop methotrexate-associated lymphoproliferative disorders (MTX-LPD) during MTX treatment. MTX-LPD occasionally regresses spontaneously after simply discontinuing MTX treatment. In patients without spontaneous regression, additional chemotherapy is required to avoid disease progression. However, the differences between spontaneous and non-spontaneous regression have yet to be elucidated. To clarify the factors important for spontaneous regression, we analyzed the clinicopathological features of 51 patients with rheumatoid arthritis who developed MTX-LPD (diffuse large B-cell lymphoma [DLBCL]-type [n = 34] and classical Hodgkin lymphoma [CHL]-type [n = 17]). We examined the interval from MTX discontinuation to the administration of additional chemotherapy. The majority of DLBCL-type MTX-LPD patients (81%) exhibited remission with MTX discontinuation alone. In contrast, the majority of CHL-type MTX-LPD patients (76%) required additional chemotherapy. This difference was statistically significant (P = 0.001). However, overall survival was not significantly different between DLBCL-type and CHL-type (91% vs 94%, respectively; P > 0.05). Thus, the morphological differences in the pathological findings of MTX-LPD may be a factor for spontaneous or non-spontaneous regression after discontinuation of MTX.