White sponge nevus （WSN） is a white lesion of the mucosa and has a characteristic spongy surface.
In this study, we examined the microstructural changes in cell adhesion structure using transmission electron microscopy in two cases of familial WSN and five cases of non-familial WSN. We found enlarged intercellular spaces and decreased bundles of keratin fibers adhering to the attachment plaque in all cases. Deformation and exfoliation of the desmosomes were also observed. These findings suggest that the cell-to-cell adhesion disorder mediated by desmosomes in cases of WSN may be the cause of abrasion-related lesion detachment. Furthermore, the expansion of intercellular spaces mediated by desmosomes was considered to be a common pathogenesis in both familial and non-familial WSN.