Difficult asthma or Churg-Strauss syndrome?

The standard management of asthma with inhaled corticosteroids and bronchodilators works in most patients. A significant minority, however, respond poorly to these medications and require frequent intermittent courses of oral corticosteroids or occasionally long term oral corticosteroid treatment. The success of the new leukotriene antagonists in reducing the need for steroids in these patients with difficult asthma seems also to be unmasking some undiagnosed cases of Churg-Strauss syndrome, the symptoms of which were apparently being controlled by steroids.

The pathophysiology of bronchoconstriction is not fully understood, but it is clear that leukotrienes, pro-inflammatory mediators arising from arachidonic acid, are important in the inflammatory processes of asthma. Several pharmacological agents, including the sulfidopeptide-leukotriene antagonists zafirlukast, montelukast, and pranlukast, have been studied in large scale randomised clinical trials.1 These trials have all been in patients with mild to moderate asthma who were not taking oral corticosteroids —or, if they were, the dose was not altered during the studies. Several cases of Churg-Strauss syndrome associated with the useof zafirlukast have been reported in the United States and more recently with montelukast in the United Kingdom.2 3

Churg-Strauss syndrome is a rare allergic granulomatous eosinophilic vasculitis characterised by …