There is no upper frontal sinus, so you may be asking about the maxillary sinus, a submucosal cyst of the left maxillary sinus, a benign lesion of the maxillary sinus. Maxillary sinus cysts can generally be categorized as mucosal cysts and mucinous cysts. Mucocutaneous cysts are most commonly found in the maxillary sinus, while mucinous cysts are rarely seen in the maxillary sinus. Mucocutaneous cysts are generally glandular ducts blocked like blowing a balloon, the more you blow the bigger, because it is mucous membrane wrapped occasionally rupture, cracked after the symptoms of nasal discharge of yellow water. Maxillary sinus mucosal cysts general examination need to do sinus ct examination can be diagnosed, the general development is relatively slow, if the cyst is small no symptoms regular review can be, if the cyst is relatively large maxillary area suffocation feeling, nasal congestion, headache situation, it is recommended that surgical treatment. It can be done endoscopically. The left side of the maxillary sinus submucosal cyst, it is recommended to timely consultation, follow the doctor’s instructions standardized treatment.