The prognostic value of positron emission tomography/computed tomography in rheumatoid arthritis patients with methotrexate-associated lymphoproliferative disorders.

Recently, methotrexate-associated lymphoproliferative disorders (MTX-LPDs) in rheumatoid arthritis (RA) have been found to commonly occur in association with iatrogenic immunodeficiency. Several factors have been reported to be related to the prognosis. We herein investigate the efficacy of 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in predicting the prognosis of MTX-LPD. We performed a retrospective analysis of the clinical features, characteristics, and outcomes of 18 patients with MTX-LPDs who were treated from 2004 to 2015. All of the patients were diagnosed with MTX-LPD based on the histological examination of biopsy specimens. Spontaneous regression was detected after the cessation of MTX in 5 of 18 cases (28%). The maximum standardized uptake value (SUVmax) of the FDG uptake on PET/CT was significantly lower, and the maximum size of the LPD-associated tumor was significantly smaller among the patients who showed spontaneous regression (p = 0.01, p = 0.04, respectively). Both the SUVmax and the maximum tumor size were related to better overall survival (p = 0.02, p = 0.04, respectively). Thus, PET/CT can be used to predict spontaneous regression and the prognosis at the diagnosis of MTX/LPD. Cases that showed spontaneous regression never relapsed during the follow-up period, despite the usage of several anti-rheumatoid arthritis drugs, including biological agents. The early detection of LPDs and the early cessation of MTX are important for the management of RA patients. An evaluation by F-FDG-PET/CT can be useful for predicting spontaneous regression and the prognosis.

Clinical characteristics of methotrexate-associated lymphoproliferative disorders: relationship between absolute lymphocyte count recovery and spontaneous regression.

Several reports have shown that patients with rheumatoid arthritis (RA) are at increased risk of developing lymphoproliferative disorders (LPD). Methotrexate (MTX) has been recognized as a major cause of LPD. Sometimes spontaneous regression (SR) occurs after withdrawal of MTX. Recent studies suggest that the early recovery of the absolute lymphocyte count (ALC) after withdrawal of MTX is associated with the spontaneous regression of MTX-LPD. We retrospectively analyzed 26 patients with MTX-LPD to identify predictive factors for spontaneous regression. The spontaneous regression after withdrawal of MTX occurred in 13 of 26 (50%) cases. We assessed the ALC at the time of MTX cessation and 1 month after cessation in 23 evaluable cases. The spontaneous regression was observed in 3 of 11 in the ALC recovery group (27%) and in 8 of the 12 in the ALC non-recovery group (67%). Thus, we could not detect any relationship between the recovery of ALC after withdrawal of MTX and the spontaneous regression. The patients in the ALC recovery group had a poorer prognosis than those in the ALC non-recovery group (2-year overall survival: 65.6 vs. 100%, p = 0.05). According to these results, the recovery of the ALC might not be useful as a predictor of the spontaneous regression. Furthermore, the existence of extranodal sites and advanced-stage were associated with non-SR. It is suspected that MTX-LPD patients with high disease activity at the time of their diagnosis might have little hope of spontaneous regression. This result indicated the importance of the early detection of MTX-LPD.