Can a sinus mucocele ever be treated as an in-office procedure or is it always outpatient at a hospital or surgery center under general anesthesia?

Sinus mucocele: I would do it in a hospital environment under general anesthesia. The risk of entering the cranium is present, so general anesthesia provides the insurance of a lack of movement with the aid of muscle paralysis which will help the surgeon. It depends also on location. Etmoid mucocel has the add risk of vision injury or smell injury.

Not sure: The answer really would depend on several things, most importantly the location of the mucocele. If easily accessible and identifiable, the possibility of an in-office attempt might increase. That has to be weighed against the risks of bleeding, lack of image guidance, poor pain control, limited equipment. In the case of a posterior ethmoid, suspect that would be unlikely in-office.

Depends on location: If this is a peripheral lesion it can be treated in the office. If it is located around the airway, that is neck or face, a general anesthetic may be preferable. Talk to your surgeon about options.