A preceeding upper respiratory infection is usually identified. Drugs such as penicillin, ampicillin, erythromycin, chlorpromazine, and acetylsalicylic acid may also precipitate the disease. Infections with Streptococcus and Helicobacter pylori gastritis have been implicated although many other bacteria and viruses have been implicated. IgA immune complexes form and deposit within the skin and affected organs. This leads to complement activation and subsequent vascular damage.
Patients usually recover although a small percentage of patients have persistent renal disease.
The histology is a leukocytoclastic vasculitis. The renal outcome of 34 patients with Henoch-Sch nlein purpura nephritis was assessed clinically and by grading acute and chronic renal lesions using a system we applied to primary IgA nephropathy. On a median follow-up period of 65 months, hypertension and the serum levels of creatinine and proteinuria at the time of renal biopsy were correlated with renal survival. Of these, only glomerular necrotizing lesion and cellular crescent were correlated with the renal survival. On follow-up, these chronic renal lesions were predictors of subsequent clinical events associated with disease progression, such as impaired renal function, significant proteinuria, and development of hypertension.