A 95-year-old man has noted swelling of his lower lip for the past month. On examination, there is a fluctuant, 1-cm nodule with a blue, translucent hue just beneath the oral mucosa on the inside of his lip. The lesion is excised, and on microscopic examination shows granulation tissue. What is the most likely etiology for this lesion?

The clinical and histologic features suggest a mucocele of a minor salivary gland, which is most often the result of local trauma in the very young and very old. There is either rupture or blockage of a salivary gland duct. Chili peppers contain capsaicin, which evokes a sensation of tingling and burning pain by activating a nonselective cation channel, called VR1, on vanilloid receptors of sensory nerve endings; there is no significant tissue damage. Social behavior may be a risk factor for infections such as herpes simplex virus. HIV infection is most often associated with oral thrush (candidiasis) and with herpes simplex virus infections. Oral leukoplakia may appear in various intraoral sites and on the lower lip border, and pipe smoking and tobacco chewing are implicated in the development of these white patches. Irritation from misaligned teeth or dentures also may produce leukoplakia. In some parts of the world, the chewing of betel nut is a risk factor for oral cancer.