An MRI scan of the head revealed..."A retention cyst and polypoid noted in the left maxillary sinus." The definition I found for retention cyst is "one caused by blockage of the excretory duct of a gland, so that glandular secretions are retained." I'm trying to make more sense of how this type of cyst affects the rest of my body. Presumably, if this type of cyst exists in the sinuses, could it not also exist elsewhere in the body? I need some light on the nature of this type of cyst and information on its origins and treatments.