Rheumatoid nodules: MR/pathological correlation

Purpose: To demonstrate the signal characteristics of subcutaneous rheumatoid nodules in correlation to their histopathologic features. Method: The magnetic resonance imaging (MRI) features of biopsy proven subcutaneous rheumatoid nodules are described in five patients with rheumatoid arthritis established by classic criteria. Results: Two morphologic appearances of rheumatoid nodules were observed on MRI: one predominantly cystic, with enhancing peripheral component; and a second type which is predominantly solid, with uniform enhancement following gadolinium injection. Conclusion: Subcutaneous rheumatoid nodules can appear by MR as solid, cystic, or a combination of both components. This closely correlates with their histopathologic evolution.