HAIRY LEUKOPLAKIA - A white lesion appearing on the tongue, occasionally on the buccal mucosa, of patients with AIDS; the lesion appears raised, with a corrugated or "hairy" surface due to keratin projections. Oral "hairy" leukoplakia is an unusual condition, characterized by small, white, fuzzy patches which are most often seen on the sides of the tongue. This lesion has only recently been described and has so far been observed only in HlV-infected individuals. Hairy leukoplakia is believed to be caused by a member of the herpes family of viruses known as the Epstein-Barr virus. Hairy leukoplakia resembles and can be confused with oral thrush, a yeast infection of the mouth.