Comparison between classical polyarteritis nodosa and single organ vasculitis of medium-sized vessels: a retrospective study of 25 patients and review of the literature.

BACKGROUND

Polyarteritis nodosa (PAN) is a rare form of systemic vasculitis, characterized by necrotizing inflammation of medium-sized vessels. In clinical practice, the distinction is made between a limited, mostly cutaneous, form and a generalized form. The Chapel Hill Consensus Conference of 2012 on the classification of the vasculitides classifies PAN as a medium vessel vasculitis, whereas the limited forms fall under the heading 'single-organ vasculitis' (SOV), with subdivions such as 'cutaneous arteritis' (formerly called cutaneous PAN) and 'others'. In this last category, forms of PAN limited to a single organ (e.g. testicle, gall bladder or appendix) should be categorized. The relation between classical and limited forms of PAN remains enigmatic.

OBJECTIVE

To compare demographics, clinical characteristics and prognosis between SOV and generalized PAN.

METHODS

Clinical files of all patients with a diagnosis of classical or limited PAN made in the departments of general internal medicine and dermatology between 1983 and 2013 in a tertiary care university hospital were reviewed.

RESULTS

The patients of the SOV group tend to be younger, with a female predominance, while we observed a male predominance in the generalized PAN group. Relapses were more common in SOV than in classical PAN. None of the patients initially diagnosed with cPAN/SOV progressed to generalized disease.

DISCUSSION: Though SOV and classical PAN share a lot of similarities, they are probably different disease entities, based on their different demographical, clinical and prognostic characteristics. The 1990 ACR-criteria for classical PAN are too broad since they allow patients with limited disease to be classified as classic PAN.