ObjectiveTo investigate the clinical characteristics of polymyositis (PM)/dermatomyositis (DM) with acute interstitial pneumonia (AIP) as the presenting symptoms, and identify characteristics of such disease. MethodsA retrospective analysis was conducted on the hospitalized patients with PM/DM with AIP as the presenting symptoms, from October 2009 to June 2015 in the Departemnt of Respiratory Medicine, Guangzhou Institute of Respiratory Diseases. ResultsThey were two males and six females with a mean age of 54.8±7.5 years. The common clinical features included fever (8 cases), shortness of breath (8 cases), rapidly progressive exertional dyspnea (8 cases), dry cough (6 cases), decreased muscle strength (8 cases), and typical rash (7 cases). Electromyography showed neurogenic or myogenic leision in these 8 cases. Muscle biopsy revealed myositis in 7 cases. High resolution CT (HRCT) revealed widespread ground glass patterns in all patients. All patients received noninvasive positive pressure mechanical ventilation on the first hospital day. High dose of methylprednisolone or combination with intravenous cyclophosphamide were initiated on 2.3±1.4 hospital day. Six patients survived to hospital discharge and two patient died. ConclusionsThe most common symptoms in patients of PM/DM with AIP are shortness of breath, progressive exertional dyspnea, and dry cough. Typical rash is seen in most of the patients.The diagnosis can be established by combinating the characteristics of HRCT, electromyography and muscle biopsy. Earlier intervention with noninvasive positive pressure mechanical ventilation and immunosuppressive may improve clinical outcome in patients of PM/DM with AIP.