Primary soft tissue lymphoma is uncommon and little is known regarding its aetiology and pathogenesis. In a review of 37 soft tissue lymphomas we uncovered three cases associated with rheumatoid arthritis which we report herein.
The clinical records and pathology of the cases are described together with the results of in situ hybridization studies with oligonucleotide probes to Epstein-Barr virus (EBV) encoded RNA (EBER). All three patients were females with a long-standing history of rheumatoid arthritis ranging from 9 to 17 years. Each presented with a soft tissue mass in the vicinity of a joint affected by rheumatoid disease. All had received prior treatment with nonsteroidal anti-inflammatory drugs and one also received gold, penicillamine and intra-articular steroids to affected joints. None had received methotrexate. Histologically, the juxtaarticular soft tissue masses were all B-cell lymphomas. None were associated with EBV as determined by in situ hybridization.
These cases document an association between rheumatoid arthritis and soft tissue lymphoma of B-cell type, arising in the vicinity of an affected joint. Chronic local immune stimulation may have played a significant role in the genesis of these lymphomas, unlike the frequently reversible and EBV-positive lymphomas that occur in rheumatoid patients on immunosuppressive therapy.