CHURG-STRAUSS SYNDROME

Epidemiology/Clinical Manifestations. Churg-Strauss syndrome (CSS) is a rare disease observed in all age groups and occurring equally between sexes with an incidence of about 3 per million people. It is thought of as having three phases: a prodromal phase, with allergic rhinitis and asthma, an eosinophilic phase, with peripheral and tissue eosinophilia, and vasculitis of the peripheral nerve (70%-80%), lung (40%-70%, which includes eosinophilic, granulomatous and vasculitic lung disease), heart (25%-35%), skin (40%-75%), gastrointestinal tract (30%), or kidney (10%-40%). Although these phases are conceptually helpful, they may not be identifiable in all patients and they may not occur in sequence.

Diagnosis. Only about 40% of patients with CSS are ANCA positive, prominently MPO-pANCA. The histologic features of CSS include eosinophilic tissue infiltrates, extravascular granulomas, and small vessel necrotizing vasculitis. Vasculitis can be difficult to definitively establish, making clinical manifestations of greater importance in establishing the diagnosis of CSS.

Treatment/Prognosis. Prednisone, 1 mg/kg/day, is effective for many manifestations of CSS, but asthma often limits the ability for glucocorticoids to be tapered. Patients with life-threatening disease should be treated with glucocorticoids and cyclophosphamide as described for GPA. Prognosis of CSS is influenced by the presence of severe disease involving sites such as the heart, gastrointestinal tract, CNS, and kidney. CSS is characterized by frequent exacerbations of asthma, with relapses of vasculitis occurring in at least 20% to 30% of patients.

HENOCH-SCHÖNLEIN PURPURA

Epidemiology/Clinical Manifestations. Henoch-Schönlein purpura (HSP) is a small-vessel vasculitis in which 75% of cases occur before the age of 8 years, although adults can also be affected. Two thirds of patients report an antecedent upper respiratory tract infection, although no specific inciting organism has been identified.

The four primary features of HSP are cutaneous vasculitis (palpable purpura), arthritis, gastrointestinal involvement, and glomerulonephritis (20%-50%). Gastrointestinal manifestations include colicky abdominal pain, vomiting, and potentially intussusception. Unlike GPA and MPA, glomerulonephritis in HSP is rarely rapidly progressive and only 2% to 5% progress to end-stage renal failure. HSP in adults may be more severe and lead to renal insufficiency in up to 13% of patients.

Diagnosis. The diagnosis of HSP is established by its clinical manifestations. Skin biopsy is not required in most instances but reveals leukocytoclastic vasculitis with a variable degree of IgA deposition in vessel walls. Renal biopsy may have prognostic utility and is an immune complex glomerulonephritis containing IgA.

Treatment/Prognosis. HSP is a self-limited condition that may not require treatment. Glucocorticoids may decrease tissue edema, arthritis, and abdominal discomfort and lower the rate of intussusception. In the hospital setting, a recent study found that early glucocorticoid exposure was associated with benefits for several outcomes in HSP, particularly related to gastrointestinal manifestations of the disease. Glucocorticoids have not been proven to benefit renal disease and do not appear to lessen the likelihood of relapse. Uncontrolled studies suggest that glucocorticoids in combination with a cytotoxic agent may be beneficial in patients with active glomerulonephritis and progressive renal insufficiency.

The outcome in patients with HSP is excellent, with disease-related death occurring in 1% to 3%. Relapse occurs in up to 40% of cases, typically within the first 3 months after the initial episode.