 Certain malignancies cause a secondary eosinophilia or, less commonly, hypereosinophilia.These increases in blood eosinophils appear due to the release of stimulatory cytokines or invasion of the bone marrow and thereby irritation of resident eosinophils or their precursors.Malignancies associated with these effects include gastric, colorectal, lung, bladder, and thyroid cancers, as well as squamous cell cancers of the cervix, vagina, penis, skin, and nasopharyrnx.