Generally, it is impossible to judge whether the patient has melanoma directly by the blackness of toenails, and the patient needs to go to the regular hospital for preliminary diagnosis through the symptoms of toes, proliferation, family history, etc., and confirm the diagnosis through pathological and histological examination. Melanoma is a tumor derived from the malignant transformation of melanocytes, and the symptoms of melanoma in toenails manifest as diffuse nail discoloration or longitudinal pigmented bands in the nail plate, in which the pigment can spread to the proximal or lateral nail folds. Some patients also experience thickening and cracking of the nail, along with pain as well as inflammation. In addition, melanoma is more likely to spread and to involve the perinail skin. There is also a family history of melanoma, which makes people more likely to develop the disease. However, the diagnosis of melanoma can only be confirmed by histologic examination. If the patient experiences any of the above symptoms, it is advisable to visit a hospital and undergo a relevant examination.