Wegener’s granulomatosis and Churg-Strauss syndrome seem very similar. How do you distinguish between them?

It is often difficult to distinguish between Wegener’s granulomatosis and Churg-Strauss syndrome due to the presence of nasal, sinus, and pulmonary involvement in both diseases and the fact that all the classic features are rarely found in a single patient. There are many situations in which the features of systemic vasculitides overlap, and these are referred to as overlap vasculitis syndromes, similar to the overlap syndromes reported for other rheumatologic conditions.

The use of cytoplasmic antineutrophil cytoplasmic antibodies (c-ANCA) for differentiating between these two disorders is helpful (c-ANCA is usually present in high titers in Wegener’s but not in Churg-Strauss), but is not included in the current diagnostic criteria for either syndrome. The presence or absence of other features should confirm the diagnosis in most cases (Table 15-3).

Table 15-3 Wegener’s Granulomatosis versus Churg-Strauss Syndrome
			WEGENER’S		CHURG-STRAUSS
	Asthma		-		+
	Blood eosinophilia		-		+
	Perivascular eosinophils on biopsy		-		+
	Hemoptysis		+		-
	Microhematuria		+		-