Symptoms of melanoma under the toenail include changes in the shape and color of the original mole as well as ulcers and itching. Melanoma is a tumor caused by the malignant transformation of melanocytes, and its causes are mostly related to DNA damage and excessive exposure to ultraviolet rays. If a melanoma develops under the toenail, the original mole under the toenail may change, including becoming larger, bulging, and changing color to black, brown, or white. In addition, there may be ulcers, itching, recurring pain and bleeding. If the above symptoms occur, it is considered to be caused by melanoma. After the diagnosis is clear, it is recommended that the patient go to a regular hospital and cooperate with the doctor to carry out standardized treatment.