This document lists and briefly describes various oral diseases and conditions that can cause lesions in the mouth. It mentions traumatic ulcers, recurrent aphthous ulcers, major aphthous ulcers associated with Behcet's syndrome, erythema nodosum, pathergy testing, Reiter's syndrome, squamous cell carcinoma, tuberculosis, syphilis in its secondary and tertiary forms, primary herpetic gingivostomatitis, recurrent herpes labialis, herpetic whitlow, recurrent intraoral herpes, chickenpox, herpes zoster, hand-foot-and-mouth disease, herpangina, erythema multiforme minor, Stevens-Johnson