What is Churg-Strauss syndrome?

Churg-Strauss syndrome (allergic granulomatosis) is an uncommon multisystemic vasculitis that is characterized with asthma, eosinophilia, extravascular granulomas, and positive ANCA titers. The main systemic features of Churg-Strauss syndrome are summarized in Table 15-2. Pulmonary involvement and eosinophilia helps discriminate Churg-Strauss syndrome from polyarteritis nodosa. The primary cutaneous lesions most commonly consist of palpable purpura involving the extremities, although some patients may also demonstrate fixed papules or plaques or even subcutaneous nodules. Cutaneous lesions have been reported in 45% to 70% of patients. Cutaneous involvement should be considered an important feature when present; biopsies in addition to demonstrating vasculitis of small blood vessels, frequently demonstrate large numbers of eosinophils and, less commonly, may demonstrate extravascular granulomatous inflammation.

Table 15-2. Clinical Features of Churg-Strauss Syndrome
	FINDING		SENSITIVITY
	Asthma		100%
	Blood eosinophilia >10%		95%
	Paranasal sinus abnormalities		86%
	Mononeuropathy or polyneuropathy		75%
	Pulmonary infiltrates		40%
	Extravascular (perivascular) eosinophils		14%
	History of seasonal allergies		-