A detailed analysis on the causes of peripheral blood eosinophilia by Lombardi and Passalacqua1 was greatly appreciated in terms of providing clinicians with directions in evaluating this common clinical problem. In addition to the disorders mentioned by the authors, we would like to raise the awareness of iatrogenic eosinophilia (most cases of which are induced by drugs and less frequently by radiocontrast materials2) as a common cause of peripheral blood eosinophilia, especially in developed countries. Clinical presentations vary from simple laboratory abnormalities to lethal episodes. Avoidance of the culprit agent is essential when treatment is needed. It may complicate underlying disorders associated with eosinophilia. Considering these possibilities, clinicians should always keep iatrogenic eosinophilia in mind when evaluating patients with peripheral blood eosinophilia.
Koga T, Aizawa H. Iatrogenic Eosinophilia. Arch Intern Med. 2004;164(1):106. doi:10.1001/archinte.164.1.106-a