Wells' syndrome, insect bites, and eosinophils.

Wells' syndrome is an idiopathic, recurrent, inflammatory dermatosis that appears to result from "dysregulated" tissue eosinophilia. The disease usually remits, and the course is benign despite occasional constitutional symptoms. The histology includes flame figures produced by the deposition of major basic protein on collagen bundles by eosinophils. Flame figures are not unique to Wells' syndrome. The term "eosinophilic cellulitis" is ambiguous, since it has been used for both Wells' syndrome and any eosinophil infiltrate with flame figures. Clinical descriptions suggest that insect bites may precipitate the initial or subsequent episodes of some cases. Insects may also be the vectors for parasitic diseases that should be considered in the differential diagnosis. Drugs and infections, including tinea, may also precipitate episodes. Wells' syndrome may be superimposed on chronic urticaria or may complicate the course of a myeloproliferative disease. The relationship of Wells' syndrome to other idiopathic diseases with eosinophilia is unknown.