BI49 Vasculopathic cutaneous ulceration as a marker of severe systemic disease in anti-MDA5 dermatomyositis

Abstract

Anti-melanoma differentiation-associated protein (MDA)5 dermatomyositis (DM) is a rare subtype of DM characterized by prominent cutaneous disease, minimal or absent muscle involvement (hypomyopathic or clinically amyopathic DM) and a strong association with interstitial lung disease (ILD), particularly rapidly progressive ILD (RP-ILD). Although uncommon, anti-MDA5 DM carries significant morbidity and mortality, with reported mortality rates exceeding 50% in patients with RP-ILD. Cutaneous features are variable and include classical dermatomyositis signs as well as more specific vasculopathic manifestations, such as deep, painful cutaneous ulceration and palmar papules, which may indicate severe systemic disease. We report a 27-year-old man with no prior medical history who presented with fevers, weight loss, inflammatory polyarthritis, tenosynovitis and a generalized pruritic rash following a presumed viral illness. Initial investigations demonstrated marked hyperferritinaemia, positive parvovirus B19 IgM, and bilateral pulmonary consolidations on computed tomography imaging. He improved transiently with oral cortico­steroids; however, subsequent investigations revealed anti-MDA5 antibody positivity with normal creatine kinase, and progressive restrictive lung disease with severely impaired gas transfer. A diagnosis was made of anti-MDA5-associated ILD, likely precipitated but not driven by parvovirus B19 infection. Serial imaging demonstrated ongoing radiological progression despite escalating corticosteroid therapy and oral tacrolimus. Treatment with cyclophosphamide was planned. The clinical course was complicated by the development of severe, painful ulceration of the hands and elbows, initially treated as infection. Dermatology assessment, supported by negative microbiological investigations, favoured vasculopathic ulceration secondary to anti-MDA5 DM. Despite multidisciplinary management and high-dose systemic immunosuppression, the patient developed RP-ILD with acute interstitial pneumonitis, pulmonary hypertension and cardiac dysfunction, and died 6 months after the initial presentation. This case highlights the pivotal role of dermatologists in identifying high-risk cutaneous features in anti-MDA5 DM, interpreting their prognostic significance and markers of severe systemic disease, and influencing early multidisciplinary escalation of care in this life-threatening condition.