What does a complex cystic mass mean with multiple thicken septation?

High risk for compli. Where is your cyst located?
In general cysts are benign and can be ignored unless they are larger than 5cm and have septate walls(complex cyst). Such cysts have a small risk of becoming cancerous. Therefore they require closer monitoring or preferably a surgical removal. Consult your doctor for advice to follow this cyst till it is determined to be benign... which may require surgical removal.