A syndrome comprising asthma, allergic rhinitis, pulmonary and systemic small-vessel vasculitis, and extravascular granulomas was described in 1951 by Churg & Strauss, mainly from autopsied cases (1). Clinical studies of patients with polyarteritis nodosa, associated asthma, pulmonary in®ltrates, and eosinophilia had been reported previously (2±5). Churg & Strauss described the pathologic lesions and distinguished this entity from polyarteritis nodosa. They described basic anatomic changes consisting of ``widespread vascular lesions of the type seen in polyarteritis nodosa, and of characteristic tissue alteration in the vessel wall and in the extravascular system. This tissue alteration . . . comprised necrosis of eosinophilic exudate, severe `®brinoid' collagen change, and granulomatous proliferation of epithelioid and giant cells.'' Churg & Strauss considered it to be a distinct histopathologic entity which they termed ``allergic granuloma''.