From the Hip to the Kidney: Suspected Infection-Associated Immunoglobulin A Vasculitis in the Setting of Chronic Methicillin-Sensitive Staphylococcus aureus Prosthetic Joint Infection.

Immunoglobulin A vasculitis (IgAV), formerly known as Henoch-Schönlein purpura, is a small‑vessel vasculitis characterized by immunoglobulin A-predominant immune complex deposition in vessel walls and the glomerular mesangium. Although most commonly observed in children, adult‑onset disease is less frequent and is associated with a higher risk of significant renal involvement and poorer clinical outcomes. We report the case of a 56‑year‑old man with alcoholic cirrhosis and chronic methicillin‑sensitive Staphylococcus aureus prosthetic joint infection who presented with progressive anasarca and a diffuse non‑blanching petechial rash. Laboratory evaluation demonstrated elevated inflammatory markers and acute kidney injury with a serum creatinine of 1.9 mg/dL (baseline approximately 1.0 mg/dL one month prior). Urinalysis revealed 3+ proteinuria and microscopic hematuria. Serologic testing, including antinuclear antibodies, antineutrophil cytoplasmic antibodies, anti‑glomerular basement membrane antibodies, complement levels, cryoglobulins, hepatitis panel, human immunodeficiency virus testing, and rheumatoid factor, was negative or non‑reactive. Renal biopsy demonstrated immunoglobulin A-dominant glomerulonephritis with mesangial hypercellularity and crescent formation. Skin biopsy demonstrated leukocytoclastic vasculitis. Culture obtained from the prosthetic hip abscess grew methicillin‑sensitive Staphylococcus aureus. These findings support a diagnosis of suspected infection‑associated IgAV occurring in the setting of chronic prosthetic joint infection. This case highlights the importance of recognizing chronic infections as potential triggers of immunoglobulin A-mediated vasculitic disease in adults and emphasizes the need to differentiate systemic IgAV from infection‑associated immunoglobulin A-dominant glomerulonephritis.