xanthoma n. A condition of the skin characterized by irregular yellow nodules particularly on the eyelids, neck, and back. It has been attributed to disturbances of *cholesterol metabolism. A verruciform xanthoma is an uncommon solitary xanthoma of the oral tissues usually occurring later in life. It is a painless *benign lesion resembling a *papilloma; it is usually covered with a rough yellowish-white *keratinized layer and is most commonly found on the gingivae or alveolar mucosa. It may occur in response to local trauma but may also be associated with more serious diseases, even immune suppression. It is treated by conservative surgical excision.
X-bite n. See BITE.
xenograft (heterograft) n