Amyopathic Dermatomyositis with Interstitial Lung Disease: A Rare Type of Dermatomyositis with Accelerated Mortality Rate

Abstract

Background: It was observed that there have been cases with pathognomonic skin lesions of Dermatomyositis, but without muscle weakness and abnormal skeletal muscle enzymes, hence they did not satisfy the Peter and Bohan criteria, and management became undirected. Until in 1993, Euwer and Sontheimer published the diagnostic criteria for Amyopathic Dermatomyositis, a type of Dermatomyositis, without proximal muscle weakness and elevated skeletal muscle enzymes. Setting: St. Luke’s Medical Center, Quezon City, Philippines. Case: We report here a case of a 59-year old female who was admitted for shortness of breath presenting with hyperpigmented papules over the metacarpophalangeal joints. One week before admission, fever, productive cough, and progressive shortness of breath developed prompting hospital admission. She arrived at the ER tachypneic with oxygen saturation of 55% at room air. She had intercostal retractions and crackles on both lung fields. There were violaceous macular rashes on the metacarpophalangeal, and proximal interphalangeal joints of both hands. Neurological examination was normal. Diagnostics: Chest CT scan revealed diffuse ground glass opacities with interstitial thickening consistent with Interstitial Lung Disease (ILD). The serum Creatine Kinase level and electromyography were normal. Skin biopsy showed perivascular lymphohistiocytic infiltrates, suggestive of dermatomyositis. Conclusion: Dermatomyositis is rare and the Amyopathic type is more uncommon (incidence of 2.08/1,000,000 population). Recognizing it can be a challenge. Amyopathic Dermatomyositis (AMD) patients have 80% survival in less than a year and drops to 60% if ILD develops. Hence, early diagnosis and aggressive management are imperative.