Methotrexate-induced panniculitis in a patient with rheumatoid arthritis.

Methotrexate-induced accelerated nodulosis (MIAN) is not an uncommon adverse effect associated with the use of the methotrexate in rheumatoid arthritis. Limited case reports describe panniculitis as a pathological finding in this setting. A 31-year-old female with seropositive rheumatoid arthritis on methotrexate therapy presented with a 2-week history of sudden onset of painful infiltrated subcutaneous nodules on both forearms. Based on clinical and histological findings, a diagnosis of methotrexate-induced panniculitis was made. The majority of MIAN case reports that we reviewed showed characteristic pathological findings of classic rheumatoid nodules; few reported panniculitis as a finding. This case illustrates the importance of recognizing this phenomenon as methotrexate-induced panniculitis should be considered in the differential diagnosis of any patient receiving methotrexate presenting with a recent history of accelerated nodulosis. Discontinuation of methotrexate remains controversial.