Diagnosis corticosteroid hypersensitivity

Corticosteroids are the current standard treatment of OP (2,6,9,11,16-19), although spontaneous improvement has occasionally been reported (2). Clinical improvement is usually observed within two days after treatment onset. At imaging, pulmonary infiltrates usually markedly improve within a few days and disappear completely within a few weeks. The speed of response to corticosteroids in OP is slower than in chronic idiopathic eosinophilic pneumonia, but faster than in NSIP and roughly comparable to hypersensitivity pneumonitis. The spectacular and reproducible response to corticosteroids can further be considered as an additional diagnostic feature of the clinical syndrome of OP, and if this response is poor, the initial diagnosis should be reconsidered. Removal of the causing agent should be done in secondary OP, whenever possible. 

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