INTRODUCTION
Dermatomyositis is an idiopathic inflammatory myopathy. In its classic form, it presents with muscle weakness and cutaneous findings, although an amyopathic form also exists. The heliotrope rash and Grotton’s papules are pathognomonic cutaneous features of dermatomyositis.1 Other cutaneous features include scalp pruritus, hip and thigh erythema (holster sign), photosensitive poikilodermatous eruption (shawl sign), violaceous erythema on the extensor surfaces, and periungual and cuticular fraying (Samitz sign).1 In addition patients may have calcinosis. Patients can also have multi-organ system involvement including most commonly pulmonary fibrosis and hypertension, but also oesophageal disease, arthritis, and cardiac dysfunction.1The mainstay of therapy for dermatomyositis has traditionally consisted of systemic corticosteroids, especially in early muscle prominent disease.1,2 However, 25% of patients with dermatomyositis do not respond to steroids and 25-50% develop adverse reactions.1,2 In addition, long term steroid therapy has significant adverse risks. Therefore, steroid-sparing agents are often needed.There is growing evidence that rituximab may be an effective therapy in patients whose disease is refractory to steroids.3-7 Although, some studies have found limited results.8,9 Rituximab is a chimeric murine human monoclonal antibody that is directed against the CD20 antigen expressed on B cells.10 Although the pathogenesis of dermatomyositis is poorly understood, it is thought that humoral-mediated complement activation leads to the inflammation of endothelial cells, which allows activated T cells to migrate to muscle and cause ischemia.11 Thus rituximab may act to decrease the B-cell production of the autoantibodies. This study is a retrospective review of cases to evaluate the effect of rituximab on the cutaneous and muscle manifestations of dermatomyositis.
METHODS
This study was approved under MGH IRB (Protocol 2014P001402). We used the Partners Healthcare Research Patient Data Registry (RPDR) to identify patients with at least one ICD-9 diagnostic code of dermatomyositis and who had been treated with rituximab between January 2000 and July 2014.Each medical record was reviewed by the authors in order ensure that the patient had a rheumatologist or dermatologist confirmed diagnosis of dermatomyositis and the patient had received rituximab specifically for the treatment of this condition. To determine baseline characteristics, we reviewed medical records from the visits immediately prior to treatment with rituximab. We recorded immunosuppressive medications and laboratory results. Muscle weakness was noted, if it was described in the medical record. The presence of skin disease was noted if the medical records described skin disease consistent with dermatomyositis. If a patient was seen by both a
