Electron microscopic observation of erythema nodosum with the eosinophilic infiltration. A case report.

The presence of eosinophils localized within an inflammatory skin lesion of a patient with erythema nodosum has been studied by electron microscopy. Among the intact eosinophils seen in the cellular infiltration, some underwent necrosis and released membrane-bound, free eosinophil granules into the interlobular septa of the subcutaneous fat. Such granules, identified by their central crystalline cores, often showed granular changes with core dissolution and were found scattered in the edematous space between the collagen bundles. A few intact eosinophils that showed minor alterations of cytoplasmic granules were also present. The significance of these findings, which may enhance endothelial permeability, is discussed.