The probability of cancerous transformation of nevus of onychomycosis is 1～2%. Naevus of nail belongs to a kind of benign tumor, generally will not be cancerous, only a very small number of patients who have been stimulated for a long time may lead to cancer, the malignant transformation rate is 1~2%, which is rare in clinic. Naevus of Onychomycosis does not have much effect on health, it is recommended to closely observe its status, if there is no change for a long time, there is no need for special treatment and no need to worry about it; however, if there is overgrowth or atypical hyperplasia, then it is necessary to carry out surgery in time to excise the nevus of Onychomycosis, so as not to cause malignant transformation due to its continuous growth. If the nevus has evolved into carcinoma, radical surgery is needed to remove the nevus, and radiotherapy and chemotherapy will be carried out according to the pathological results after the surgery; for patients who cannot undergo surgery, chemotherapy, radiotherapy and other comprehensive treatments can be carried out.