Fibroblastic rheumatism is a rare dermatoarthropathy characterized by the sudden onset of cutaneous nodules, flexion contractures, and polyarthritis. Histopathology in the correct clinical context confirms the diagnosis. Treatment is based on observational data from single case reports.

We describe 4 cases, review histologic findings, and discuss therapeutic responses.

Cases coded as fibroblastic rheumatism were retrieved from institutional and consultation files. Medical charts and biopsy specimens were reviewed. Elastic stains and immunostains for smooth muscle actin, S100, CD34, desmin, and epithelial membrane antigen were performed on selected cases.

Four cases were identified. Patients displayed cutaneous nodules and arthralgias. Flexion contractures/decreased motion were present in two patients; one patient had associated Raynaud phenomenon and erosive joint disease. Biopsy specimens demonstrated a fibroblastic proliferation associated with a collagenous stroma. Growth patterns varied from cellular fascicles to paucicellular randomly arranged spindle cells. Elastic fibers were absent in all cases tested (3/3). Immunohistochemical stains demonstrated immunoreactivity for smooth muscle actin in one of 3 cases in a myofibroblastic pattern. Other stains were negative. One patient had complete resolution of disease with methotrexate. One patient partially responded to interferon-alfa and ribavirin and was subsequently treated with methotrexate with additional improvement. One patient had limited response to all therapies attempted. One patient was lost to follow-up.

Small sample size (n = 4) is a limitation.

Our data expand the clinical, histologic, and therapeutic response data on fibroblastic rheumatism. Correlation with clinical history is critical to avoid misdiagnosis as other fibrosing lesions. Methotrexate and interferon-alfa are potential therapies.