Verruciform xanthoma of the oral mucosa: an immunohistochemical and ultrastructural study of two cases.

Verruciform xanthoma is an uncommon benign lesion of unknown aetiology and pathogenesis. Two cases of verruciform xanthoma are presented together with an immunohistochemical and ultrastructural study. One case co-occurred with an odontogenic keratocyst which, to our knowledge, has not been previously reported, and another case occurred on masticatory mucosa with an asymptomatic, granular, exophytic lesion causing a cleft-like gingival recession. In an immunohistochemical study using antibodies to macrophage (CD 68[KP1]), alpha-1-antitrypsin, vimentin, desmin, keratin, neuron-specific enolase (NSE) and S-100 protein, the characteristic foam cells of verruciform xanthoma showed strong positive staining for CD 68[KP1] and vimentin and weak positive staining for alpha-1-antitrypsin, while the other antibodies were negative. As in previous studies, S-100 protein positive dendritic cells were detected in lesional connective tissue. In addition, the ultrastructural findings revealed characteristics of macrophages containing varying sized lipid vacuoles and degenerating epithelial cells. These findings support the concepts that the foam cells in verruciform xanthoma are of monocyte-macrophage lineage and that the epithelial degeneration from uncertain causes may be related to the pathogenesis of the lesion.