P103 Beyond the surface: cutaneous vasculitis as a sign of fatal underlying conditions

Abstract Cutaneous vasculitis can serve as an initial manifestation of a wide range of underlying medical conditions, posing a significant diagnostic challenge. This case highlights the importance of a systematic diagnostic approach to differentiate immune-mediated vasculitis from infection-driven vasculitis, as misdiagnosis and inappropriate treatment, such as immunosuppression, can worsen patient outcomes. We present the case of an 81-year-old woman with a complex medical history, including moderate left ventricular systolic dysfunction (LVSD), who presented with worsening purpura, haemorrhagic blisters and necrotic ulcers on the distal part of all extremities. She also reported new exertional shortness of breath and bilateral leg swelling. Initial laboratory investigations revealed mild normocytic normochromic anaemia, elevated inflammatory markers, and mild acute kidney injury. Vasculitic investigations were notable for positive antinuclear antibodies and antineutrophil cytoplasmic antibodies at low titres, with normal myeloperoxidase and proteinase 3 levels. Given the clinical and laboratory findings, a provisional diagnosis of cutaneous leucocytoclastic vasculitis was made. A few days later, the patient’s condition worsened, with progressive renal impairment and rising inflammatory markers. Staphylococcus aureus was isolated from peripheral blood cultures and a leg ulcer swab, prompting the initiation of intravenous flucloxacillin and an urgent inpatient transthoracic echocardiography (TTE) based on the microbiologist’s advice. The TTE revealed severe LVSD and a mobile echogenic mass in the supravalvular region of the aortic valve, consistent with infective endocarditis (IE). Despite targeted antibiotic therapy, her clinical condition deteriorated further, and she developed worsening cutaneous vasculitis and systemic complications. After 13 days of IE diagnosis and 23 days of hospitalization, a multidisciplinary team discussion led to the decision to transition the patient to palliative care. She passed away shortly thereafter. This case underscores the diagnostic complexity of cutaneous vasculitis in the setting of systemic infection, particularly infective endocarditis. Staphylococcus aureus, a known causative agent of IE, has been implicated in the development of immune-complex-mediated vasculitis. This highlights the importance of considering infection as a cause of vasculitis, particularly when atypical clinical features, systemic symptoms or progressive organ dysfunction are present. This case emphasizes the need for a comprehensive diagnostic approach before initiating immunosuppressive therapy, as timely identification and management of infection-driven vasculitis are crucial for optimizing patient outcomes.