Henoch-Schönlein Purpura: Skin and Systemic Findings

Overview / Definition Henoch-Schönlein Purpura (HSP), also referred to as IgA vasculitis, is a form of small-vessel vasculitis primarily seen in children. It is characterized by the deposition of IgA antibodies in the skin and other tissues, leading to inflammation and a spectrum of clinical symptoms. Epidemiology HSP is the most common form of vasculitis in children, typically occurring between ages 2 and 6 years. The incidence is approximately 10-20 cases per 100,000 children per year, with a slight male predominance (2:1 ratio). Seasonal outbreaks have been observed, often following respiratory infections. Pathophysiology / Mechanism The exact pathophysiological mechanism of HSP remains uncertain, but it is thought to involve: Increased IgA production in response to infections, particularly respiratory. Immune complex deposition in small blood vessels, leading to vasculitis. Activation of the complement system, contributing to inflammation. Genetic predisposition, with some cases linked to HLA typing. Clinical Presentation The classic clinical presentation of HSP includes a tetrad of symptoms: Palpable purpura: Typically located on the buttocks, legs, and sometimes the trunk. Arthralgia: Joint pain and swelling, commonly affecting the knees and ankles. Abdominal pain: Often colicky in nature, associated with gastrointestinal manifestations such as nausea and vomiting. Renal involvement: Ranging from mild hematuria and proteinuria to more severe forms of nephritis. Clinical Pearls: Renal involvement can occur in up to 50% of cases and may present weeks after the initial symptoms. Monitor renal function closely. Diagnosis / Workup Diagnosis of HSP is primarily clinical but can be supported by laboratory findings: Skin biopsy: May reveal leukocytoclastic vasculitis with IgA deposition. Laboratory tests: CBC may show leukocytosis; urinalysis may show hematuria and proteinuria. Renal ultrasound: Indicated in cases with significant renal involvement. Differential Diagn