Nomenclature of vasculitic syndromes: a historical perspective.

Since the original description of periarteritis nodosa (PAN) in 1866, the number of recognized forms of so-called idiopathic vasculitis has risen to about a dozen. Their relation to each other and their nature remain unclear, although the recent discovery of antineutrophil cytoplasmic autoantibodies (ANCA) promises a clue to the origin of at least some of them, particularly Wegener's granulomatosis (WG) and perhaps also Churg-Strauss syndrome (CSS). On the other hand, PAN appears to be a nonspecific syndrome of various etiologies.