Left maxillary sinus cyst is a type of sinus cyst, most of which have no clinical symptoms and are detected by patients during a cranial CT or cranial MRI. Many patients will come to the clinic with headaches and dizziness and will need to complete a cranial imaging study to rule out organic disease in the brain. This is when a scan of the entire head is done and the organs adjacent to the brain can also be seen. The maxillary sinus is one of the paranasal sinuses and is located on either side of a person’s nose, behind the cheekbones. This area should normally be clean and clear, and if the patient has had an upper respiratory infection and has pus nasal discharge that is retained here and cannot be completely drained, it may form a cyst later on when it is closed inside. Normally there are no symptoms and the patient will not have signs of infection such as fever and headache. If the cyst is secondary to infection, the patient will have the above symptoms and needs to be discharged, and may consider quintuple surgery or anti-infection treatment.