It is well established that rheumatoid arthritis is associated with an increased risk of lymphoma. The use of tumor-necrosis factor-α inhibitors as a therapy in rheumatoid arthritis has been related to higher incidence of lymphoma arising at atypical and/or unusual locations; however, recent data shows their safety. We report the case of a 79 year-old woman with rheumatoid arthritis treated with infliximab, who presented a primary breast lymphoma with cutaneous involvement.