The course of dermatomyositis (DM) can be complicated by multi-organ failure, by complex pathophysiological mechanisms involving autoantibodies. Pulmonary complications are the leading cause of mortality, accounting for 30% of deaths. There is a strong association between DM and interstitial lung disease (ILD); clinically amyopathic dermatomyositis (CADM) has a stronger association with ILD as compared to a classic form of DM. ILD can be in the form of fibrosing alveolitis, interstitial pneumonia, and desquamative interstitial pneumonia or diffuse alveolar hemorrhage. Autoantibodies linked to ILD are anti Jo-1, PL12, PL7, EJ, and OJ and anti Mi 2. Our case describes a fifty-three years old woman who presented with symptoms of lower respiratory tract infection, diagnosed with CADM based on typical skin rash and polyarthritis and anti-CADM 140 antibodies. Systemic steroid therapy (initiated after ruling out sepsis) failed to provide improvement. The medical course was complicated by multisystem involvement (respiratory failure, cerebral edema, renal failure, coagulopathy, hepatic failure, and thromboembolism). Transthoracic echocardiogram revealed thrombus in the right ventricle, which was the result of the prothrombotic state, and the patient expired on day tenth of hospitalization. Our case describes a unique case of right ventricular thrombosis secondary to macrophage activation syndrome (MAS).2020 AME Case Reports. All rights reserved.