“…The widespread granulomata resemble those found in experimental serum sickness (Rich, 1942), "allergic granulomatosis " (Churg and Strauss, 1951), and many cases of fatal drug sensitivity (Waugh, 1952;O'Brien and Storey, 1954;Rasmussen, 1955;and others). The necrotizing vascular lesions are morphologically similar to those in polyarteritis nodosa of the " microscopic " variety (Davson et al, 1948), "hypersensitivity angiitis" (Zeek, 1952(Zeek, , 1953, and experimental hypersensitivity (Rich and Gregory, 1943;McKeown, 1947;Crawford and Nassim, 1951;Germuth et al, 1955;and others). As Fahey et al (1954) have remarked, Wegener's granulomatosis closely resembles, both clinically and pathologically, several other uncommon diseases " which run in a spectrum from pure necrotizing and granulomatous processes without vasculitis through mixed forms to pure arteritis without granulomas."…”