SPECIFIC MUCOSAL EROSIONS IN HYPEREOSINOPHILIC SYNDROME - EVIDENCE FOR EOSINOPHIL PROTEIN DEPOSITION

Background: Mucosal erosions can be a presenting feature of the hypere osinophilic syndrome. The aim of this study was to analyze in situ the presence of eosinophil proteins and the state of eosinophil activatio n. Biopsy specimens of mucosal lesions and normal skin were taken from two men with oral and genital erosions typical of hypereosinophilic s yndrome. Tissue sections were immunohistochemically labeled with anti- major basic protein, anti-eosinophil-derived neurotoxin, and anti-eosi nophil peroxidase antibodies. The same specimens were also subjected t o electron microscope examination. Observations: Eroded specimens disp layed areas of eosinophil spongiosis within which extracellular deposi ts of eosinophil peroxidase, major basic protein, and eosinophil-deriv ed neurotoxin were present. In normal skin, only a few eosinophils wer e present within tile capillary lumen, and no extracellular deposits o f these proteins were seen. Under the electron microscope, the cytopla smic membranes of eosinophils located around the erosion were disrupte d. Remnants of necrotic keratinocytes were found near these lysed eosi nophils. Conclusion: As with other involved organs in hypereosinophili c syndrome, mucosal erosions seem to be the consequence of eosinophil protein release.