Subclinical renal involvement in essential cryoglobulinemic vasculitis and classic polyarteritis nodosa

Renal vasculitis is usually associated with anti-neutrophil cytoplasmic antibodies (ANCAs). However, non-ANCA patients constitute a rarely studied variant of renal vasculitis. The aim of the present study was to demonstrate the features of renal involvement in patients with primary systemic non-ANCA associated vasculitis (NAAV) and compare essential cryoglobulinemic vasculitis (ECV) with classic polyarteritis nodosa (PAN).

The study included 30 patients with primary systemic non-ANCA associated vasculitis (NAAV). Fifteen with ECV and another 15 patients with classic PAN. The patients were recruited from the Rheumatology and Internal medicine departments and outpatient clinics of Cairo University Hospitals. The patients had no or mild renal involvement at entry and the ANCA was negative as tested by immunoflourescence and ELISA. Renal biopsy was performed for all the patients and histopathologically studied.

Renal biopsy abnormalities were seen in six females. One patient with PAN showed renal vasculitis and membranoproliferative glomerulonephritis (MPGN) and was HBV and ANA positive. The patient had negative HCV and cryoglobulins. Five patients with ECV-associated HCV had findings; one had chronic interstitial nephritis and was HBV positive. The other four were HBV negative with MPGN in two, focal proliferative and crescentic GN in one patient each.

Increased understanding of the manifestations of systemic vasculitis is likely to provide the basis for the use of more selective immunomodulatory therapies in the future. It is our hope that this study will raise awareness of the non ANCA-associated vasculitic renal involvement.