Background The clinical presentation of HSPN in adults is severe with relatively poor outcome. As HSPN primarily affects children, evidence on the treatment of HSPN in adults is quite limited. We report a case of severe HSPN with acute kidney injury and proteinuria that was treated successfully.

Case Report 53 year old obese female, with a history of type 2 diabetes mellitus and hypertension presented with nonblanching purpuric vasculitic rash on anterior abdominal wall and posterior surface of both arms. Vasculitis was associated with nephrotic range proteinuria (30 g/day), microscopic hematuria and acute kidney injury with eGFR 43 mL/min/1.73 m2, creatinine 123 μmol/L, urea 8.0 mmol/L and albumin 30 g/L on admission that later declined to eGFR 20 mL/min/1.73 m2 and creatinine 231 μmol/L during the hospital stay. There was no arthralgia, gastrointestinal symptoms or macroscopic hematuria. She was treated with oral prednisolone after skin biopsy report of florid small vessel or leukocytoclastic vasculitis, negative for immunofluorescence staining. Vasculitis screenings were negative for ANA, anti‐dsDNA, anti‐GBM, ANCA, hepatitis B, hepatitis C and serum C3 and C4 levels. Renal biopsy reported crescentic glomerular nephritis containing 93% cellular crescents and IgA deposits following which oral cyclophosphamide was initiated. Skin rashes subsided and renal disease improved to eGFR 61 mL/min/1.73 m2 and creatinine 93 μmol/L but proteinuria persisted at 11 g/day. Cyclophosphamide was switched to cyclosporin after 6 months of treatment and oral steroid tapered. A few months after initiation of cyclosporine, proteinuria improved persistently at <1 g/day.

Conclusion This case highlights the severity of renal involvement in adult‐onset HSPN. Aggressive treatment is required when severe crescentic nephritis and nephrotic syndrome are observed simultaneously at presentation in adult HSPN and the treatment can alter the course of renal disease.