Systemic Vasculitides



Polyarteritis nodosa (PAN) is a multisystem disorder associated with fibrinoid necrosis of me­dium-sized arteries. The kidneys are commonly involved at the level of lobular and interlobular arteries, particularly at bifurcations of these ves­sels. A renal arteriogram demonstrating aneu­rysms of these vessels is virtually diagnostic of the disorder. Chronic hepatitis B antigenemia is seen in a significant number of patients with PAN.

Mild azotemia and microhematuria, but with­out hypertension, are seen in over 75 per cent of patients with PAN. Glomeruli show only is­chemic changes and sclerosis in these patients. A more dramatic nephritic syndrome, associated with a rapid decline in GFR and frequently as­sociated with accelerated hypertension, occurs in about one third of patients. Fibrinoid necrosis, cellular proliferation, and crescent formation are seen in glomeruli of these patients. Corticoster­oids and/or cytotoxic agents can arrest or slow the progression of disease in a significant number of patients.

The course of progressive systemic sclerosis (PSS), or scleroderma, culminates with acceler­ated hypertension associated with a rapid de­crease in renal function in 10 to 20 per cent of cases. The clinical presentation is similar to that of rapidly progressive glomerulonephritis, with the added neuroretinal features of malignant hy­pertension. The primary renal lesion is that of ex­tensive intimal proliferation in interlobular arter­ies and fibrinoid necrosis of small arteries and glomeruli. This lesion may be evident in patients who exhibit no clinical signs of renal disease. Treatment is directed toward rigorous control of hypertension, but renal failure is usually inevi­table.

Wegener’s granulomatosis is a vasculitis of small arterioles of the respiratory tract and kid­neys. The typical clinical presentation includes destructive sinusitis with nodular pulmonary in­filtrates and nephritis. The renal lesion is that of a focal, necrotizing glomerulonephritis with ex­tensive cellular proliferation. The diagnosis should be made on the basis of the clinical pres­entation plus evidence of a granulomatous vas­culitis of the respiratory tract. Differentiation from Goodpasture’s syndrome can be made on the basis of the sinus involvement and nodular, as opposed to diffuse, pulmonary radiographic changes in Wegener’s. Renal biopsies are rarely diagnostic because the diagnostic granulomatous lesion is found in vessels not commonly sampled by renal biopsy. Remarkable responses, includinga high rate of total cures, have been seen with ag­gressive cytotoxic therapy using cyclophospha­mide.