What is the pathophysiology of EGPA (Churg-Strauss syndrome)?

Updated: Dec 24, 2018
  • Author: Spencer T Lowe, MD; Chief Editor: Herbert S Diamond, MD  more...
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Answer

EGPA is a granulomatous small-vessel vasculitis. The cause of this allergic angiitis and granulomatosis is unknown. [10] No data have been reported regarding the role of immune complexes or cell-mediated mechanisms in this disease, although autoimmunity is evident with the presence of hypergammaglobulinemia, increased levels of immunoglobulin E (IgE), rheumatoid factor, and ANCA.

An EGPA-like syndrome is a rare complication that develops in steroid-dependent patients with asthma who have their oral steroid dose reduced after they start treatment a leukotriene receptor antagonist (eg, montelukast, zafirlukast). [11] It has also been reported in patients whose withdrawal of oral steroids is facilitated by use of inhaled steroids.

This complication is probably related to steroid withdrawal, which unmasks underlying EGPA, [12, 13, 14] rather than to the drugs themselves. However, in rare cases, this syndrome has developed when a leukotriene receptor antagonist has been substituted for inhaled steroids ini patients without a history of oral steroid withdrawal. [15]

HLA-DRB4 positivity may be a genetic risk factor for the development of EGPA, and may increase the likelihood of vasculitic manifestations of the disease. [16]


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