Polyarteritis nodosa when applying the Chapel Hill nomenclature--a descriptive study on ten patients

Polyarteritis nodosa (PAN) is a term that has been used to describe a wide variety of vasculitic conditions. In 1994, the Chapel Hill Consensus Conference on the nomenclature of systemic vasculitides proposed that the name classical PAN should be restricted to diseases where there is arteritis in small and medium-sized arteries without the involvement of smaller vessels. Our aim was to describe the symptoms and course of disease in PAN when the microscopic forms are excluded.

All patients with a diagnosis of PAN treated in our departments during the period 1990-2002 were eligible for this study. The diagnosis had to be confirmed by biopsy, angiography or electromyography.

Ten patients were eligible for the study. The median age was 46 yrs. Renal involvement was seen in 70% at diagnosis. After 5 yrs, 57% had experienced a relapse, which is equivalent to the relapse rate seen in microscopic polyangiitis. Organ damage was assessed by the Vasculitis Damage Index (VDI) and after 5 yrs cardiovascular and neuropsychiatric damage dominated, followed by renal damage. During the follow-up, two patients developed end-stage renal disease. The annual incidence of PAN in our local catchment area was estimated to 1.6 per million and year.

When applying the Chapel Hill nomenclature, PAN is a rare but severe disease with a high incidence of renal involvement and frequent relapses.