[Refractory dermatomyositis associated with chronic organizing pneumonia treated with rituximab: report of one case].

Chronic organizing pneumonia (COP) has often been reported as a pulmonary manifestation of collagen vascular diseases, mainly rheumatoid arthritis, but the association of COP and dermatomyositis (DM) has rarely been documented. We report a 55 year-old woman with well-documented DM and a COP. She was refractory to steroids and two other immunosuppressive agents therapy (cyclophosphamide and azathioprine). Therefore, rituximab (2 x 1 g infusions) was used for treatment. During the following weeks her strength gradually increased while creatine kinase (CK), C reactive protein and erythrocyte sedimentation rate normalized. After 6 months, she had a relapse with increased muscle enzymes, fever and moderate muscle weakness. After a second course of rituximab (2 x 1 g infusions), the patient demonstrated a remarkable clinical response as indicated by an increase in muscle strength and moderate decline in creatine kinase levels. Lung abnormalities resolved significantly on high resolution chest CT scan. Thus, B-cell depletion therapy with rituximab used alone or in combination with other immunosuppressants may be a viable option in patients with polymyositis-dermatomyositis and pneumonia refractory to current therapies.