Clinically Amyopathic Dermatomyositis Complicated by Pleural Effusion Case Report, Literature Review, and Proposed Mechanism.

Polymyositis-dermatomyositis (PM-DM) is a chronic inflammatory disorder that mainly involves muscles and skin. Clinically amyopathic dermatomyositis (CADM) is a unique subset of PM-DM with typical skin manifestations but little or no evidence of musculoskeletal involvement. Many cases of dermatomyositis and CADM are associated with internal malignancy, but pulmonary manifestations can also been seen; the most common of which is interstitial lung disease. Pleural effusion is a rare complication and may be difficult to differentiate from other causes, such as infections, heart failure, or malignancy. We report a patient with CADM complicated by rapidly progressive pleural effusions. Based on findings of this patient, as well as literature review, we suggest that the etiology of massive pleural effusion in this setting is most likely related to local immune pleuritis associated with underlying interstitial lung disease due to dermatomyositis. Optimal management should be individualized and may include immunosuppressive agents, as well as antimicrobials, and potentially other agents.