Sebaceous cysts are common benign skin lesions with a low rate of cancer. The survival time of patients with cancerous lesions needs to be determined according to the condition, and the expected survival time may range from a few months to a few years. Sebaceous cysts are very common benign skin lesions, under normal circumstances, timely surgical excision is sufficient, and the prognosis is good. If left untreated, they may ulcerate and become infected, and are prone to recurrence. Sebaceous cysts may become cancerous in a small number of patients, and most of them evolve into basal cell carcinoma, and a few of them become squamous cell carcinoma, with a cancer rate of about 2~4%. After sebaceous cysts become cancerous, the survival period of patients is related to the pathological type of the tumor, stage, treatment plan and other factors, and there are obvious individual differences. The expected survival period is difficult to assess, and it may range from a few months to a few years, and patients who have good therapeutic effects may also have a long term survival. After sebaceous cysts become cancerous, it is recommended to consult the oncology department in time and carry out standardized treatment under the guidance of doctors to prolong the survival period of patients as much as possible.