AB0611 Recurrent Cutaneous Ulcers and Interstitial Lung Disease in Dermatomyositis with Positive Anti-P155/140 Autoantibodies: an Atypical Case

Background Anti-P155/140 autoantibodies (anti-TIF1) have been reported to be associated with malignancy1; whereas melanoma differentiation-associated gene 5 (MDA5) has been identified as a DM specified autoantigen that appears to be targeted in patients with amyopathic DM with mucocutaneous ulcers and aggressive interstitial lung disease (ILD)2. Methods We reported a case of recurrent cutaneous ulcers, soft tissue infections and interstitial lung disease which was consistent with anti-MDA5 phenotype but with the presence of anti-p155/140 antibodies. Results A 51 year-old lady presented with general unwell, arthritis and skin rash. On examination, she had symmetrical arthritis, erythematous rash over upper arms, buttock, thighs and Gottron papules. She had minimum proximal limbs weakness. Skin biopsy showed linear IG A deposition which was consistent with erosive dermatomyositis. Initial serology tests were negative. Creatinine kinase was elevated at 350. Thus, a diagnosis of DM was made and the patient was treated with oral prednisolone followed by Azathioprine. 8 months later, she developed multiple ulcers in right elbow, foot and right buttock. MRI of the left elbow showed pyomyositis and partial disruption of the triceps tendon. Wound swab from the left elbow isolated Klebsiella Oxytoca. She was treated with prolong course of antibiotic. Repeat immunological test identified positive ANA and anti- p155/140 antibodies. MRI of shoulders and pelvis girdles showed extensive myositis. She underwent extensive investigations which excluded malignancy. Then, she became progressive dyspnoea. Chest images showed organizing pneumonia in both lung bases. Pulmonary function test showed restrictive lung feature. She was treated with Cyclophosphomide in combination with oral steroid. She developed infectious tenosynovitis of left middle finger following 2nd dose of Cyclophosphamide which surgical washout and antibiotic. Due to progressive ILD, she was switched to Tacrolimus and her respiratory status had stabilized since then. Conclusions This patient had clinical amyopathic dermatomyositis, extensive cutaneous ulcers, recurrent soft tissue infection and progressive ILD. Her clinical features are suggestive of the anti-MDA5 phenotype despite the presence of anti-p155/140 antibodies. In light of high prevalence of life-threatening complications related to these antibodies, we recommended intensive screening for malignancy and ILD in DM patients. References Trallero-Arag