The cause is unknown but the histology suggests a hyperimmune response with T-cells. One must rule out medication usage and other ulcerative diseases. The ulcers are usually clearly outlined with a central necrotic zone surrounded by an erythema and are found on the moveable mucosa. A traumatic ulcer is usually more irregular in outline. This patient poked the ulcer with a pencil leaving the dot at the edge.
Treatment can be topical steroids.