Whether lymphatic duct cysts can become cancerous or not depends on the changes of the patient’s lymphatic duct cysts for objective analysis. First, if the patient’s lymphatic duct cyst is small in size, there is no obvious pain and pressure symptoms of surrounding tissues, and the lymphatic duct cyst has not changed significantly within a long period of observation. At this time, the chance of lymphatic duct cyst becoming cancerous is very small and can be left untreated. Secondly, if the lymphatic duct cyst is larger in size, or the lymphatic duct cyst increases significantly in size within a short period of time, and is accompanied by pain and pressure symptoms in the surrounding tissues, or even the lymphatic duct cyst invades into other organs and tissues. In this case, lymphatic duct cysts have a higher chance of becoming cancerous, so it is recommended to have surgery to remove them as soon as possible.