Peripheral eosinophilia camouflaging anaplastic large cell lymphoma.

Eosinophilia is a nonspecific laboratory finding, often noted incidentally during routine blood analysis. When persistent, eosinophilia can herald an underlying parasitic infection, drug reaction or less commonly, a neoplastic process. Anaplastic large cell lymphoma (ALCL) and tissue eosinophilia has been described; however, such cases have not displayed marked leukocytosis with eosinophilia.