MDA5

Abstract: Abstract Anti-MDA5 dermatomyositis (DM) is a rare systemic autoimmune condition associated with clinically amyopathic DM and rapidly progressive interstitial lung disease (RP-ILD). It is associated with unique skin features including cutaneous ulceration, eyelid oedema, palmar papules and mechanic’s hands. We present two challenging cases of anti-MDA5 DM with atypical skin manifestations, complicated by RP-ILD, which unfortunately resulted in death in both patients. The first case is a 47-year-old Egyptian woman who initially presented with erythema and burning sensation of the fingertips, thigh rash, arthralgia, joint swelling, dry cough and reduced exercise tolerance. She was diagnosed with undifferentiated inflammatory arthritis and possible amyopathic DM and started on methotrexate and systemic steroids. An autoimmune panel showed weakly positive rheumatoid factor but negative antinuclear antibodies, extractable nuclear antigen, dsDNA, antineutrophil cytoplasmic antibodies and anti-Jo1. Subsequently she presented to accident and emergency with worsening breathlessness and productive cough and was admitted to the intensive care unit, treated for pneumonia. A high-resolution computed tomography (CT) scan was reviewed at a tertiary multidisciplinary team, showing an RP-ILD picture, most likely due to MDA5 DM. She was started on pulsed intravenous methylprednisolone and transferred to a tertiary centre for extracorporeal membrane oxygenation (ECMO) and consideration of rituximab. Unfortunately, she died shortly after. She demonstrated positive anti-MDA5 serology. The second case is a 60-year-old Chinese woman who initially presented to ophthalmology with left-eye oedema and was diagnosed with preseptal cellulitis. Subsequently, she presented again to accident and emergency with fatigue, unintentional weight loss, and reduced mobility. She was cachectic with ulcerating skin lesions on her shoulders and hips. Initial CT of the chest–abdomen–pelvis showed patchy consolidation in both lungs, with nodularity and ground-glass changes. She developed pyrexia and mild hypoxia and was treated for bilateral pneumonia. During admission, fasciculations in her upper limbs and tongue prompted a neurology review. Nerve conduction studies demonstrated myopathic changes. Creatine kinase was elevated, and magnetic resonance imaging of the lower limbs confirmed diffuse oedema. Concurrently, she was noted to have mechanic’s hands and Gottron papules. She developed severe type 1 respiratory failure, requiring transfer to intensive care. Repeat CT imaging showed worsening bilateral consolidation and ground-glass changes, with pleural effusions. Her rapidly progressive respiratory failure in the context of likely DM prompted urgent referral to a tertiary centre for ECMO and aggressive immunosuppression. Unfortunately, she died 3 weeks later. Autoantibody testing confirmed positive anti-MDA5 and Ro52 antibodies.