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Small-vessel vasculitis and its most common presentation, palpable purpura, often present a major diagnostic challenge to the emergency physician.
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Inflammation of small (cutaneous) vessels is the pathomorphologic end-product of a very diverse group of diseases, including infectious, malignant, and autoimmune conditions.
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Most commonly, patients will present to the ED because of systemic symptoms such as fever, malaise, and weight loss, together with skin manifestations. These include a wide range of erythematous, macular, and urticarial lesions. However, the most typical manifestation is palpable purpura. It is typically symmetrically distributed and most prominently affects pressure- and gravity-dependent areas such as the lower extremities and buttocks.
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Management and Disposition
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Management of patients presenting with small-vessel vasculitis focuses on the following two questions: (1) What is the underlying disease?, and (2) What is the extent of organ involvement? The answers to these questions will have significant impact on the treatment and disposition of the patient.
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It is often impossible to achieve a high level of diagnostic certainty in the ED. Classification of small-vessel vasculitis often requires advanced testing such as skin biopsies and autoimmune and infectious serologies, which are beyond the scope of the ED, and patients typically require hospital admission.
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Particular differential diagnoses, however, should be considered and identified as early as possible. This includes infectious endocarditis and sepsis, which can cause immune complex–mediated small-vessel vasculitis. As a result, every adult patient presenting with concern for small-vessel vasculitis requires a careful exposure history and physical exam.
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The importance of careful staging of a patient with small-vessel vasculitis cannot be overstated. The patient may only be presenting with palpable purpura but could be harboring organ- or life-threatening disease in other areas. More serious manifestations of small-vessel vasculitis include alveolar hemorrhage, mononeuritis multiplex, bowel ischemia, and glomerulonephritis.
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