Mouth ulcers are a common symptom, easy to recur, some even easy to malignant, recurrent mouth ulcers and malignant mouth ulcers or relatively easy to distinguish. You can self-identify through the following aspects: 1, find the cause of ulcers occurring Have a history of oral trauma, such as being food burns, lacerations, bites, etc.; have not suffered from oral mucosal disease; have a history of oral trauma, no oral local pressure, swelling, functional limitations and lumps, mostly recurrent ulcers. 2. Observe the shape of the ulcer surface facing the window or a place with sufficient light, poke the cheek with a stainless steel spoon handle and find the ulcer site through the mirror for careful observation. If the ulcer is found to be superficial, with a smooth surface, not higher than the normal mucosa at the edges, bright red in color, round or oval, and multiple ulcers, the possibility of benign is high; conversely, if the bottom of the ulcer is a deeper depression, with an uneven surface, elevated edges, dark red, irregular shape, and a single larger ulcer, be alert to the possibility of malignant. 3. Touch the ulcer surface, wash your hands, and gently touch the ulcer surface and its surrounding parts with your fingers, benign ulcers are soft to the touch; if you feel hard lumps around the ulcer and the base, the hardness can be compared with the hardness of the tip of the nose and forehead, such as similar to the hardness of the tip of the nose for medium hardness, and similar to the hardness of the forehead for high hardness. The higher the hardness of the ulcer, the higher the possibility of malignancy. When touching the ulcer surface feels painful is benign ulcers, on the contrary, malignant ulcers pain is not very obvious. 4, touch the lymph nodes closed, four fingers together, the right side with the left hand, the left side with the right hand, gently touch the nearby lymph nodes. The order of touching is: first touch the front and back of the ear, then the angle of the jaw, and finally along the side of the neck all the way to the clavicle, carefully identifying whether there are enlarged lymph nodes. If a swollen lymph node is felt, it should be carefully felt several times to identify the swollen lymph node. Usually swollen lymph nodes caused by benign ulcers have a smooth, mobile surface. If the swollen lymph nodes are felt, the surface is uneven and inactive, which often indicates malignancy. Based on the above self-examination results, if malignancy is suspected, further examination in hospital must be carried out as soon as possible.