Is operation necessary for treating cyst in the sinus cavity. can i avoid operation? if not, which type i should prefer traditional or endoscopic?

Surgery not required: Most cyst in the sinus are called mucus retention cyst and are benign. They rarely cause a problem and can just be observed. However, it's best you have an ENT review a sinus ct scan with you to see if it could be causing any symptoms you may be having.

No: Antral cyst does not require surgery unless it is very large and obstructs the outflow tract of your maxillary sinus.

Sinus Cyst: If a cyst is found on routine x-rays or even a ct scan of the sinuses, generally, no treatment is necessary. Unless there is pain over the sinus with the cyst or you suffer from frequent sinus infections, most ents would not recommend any treatment is needed.