Serous (mucous) cysts of the nasal sinus are categorized into serous cysts of the nasal sinus and mucous cysts. These cysts can occur in any nasal sinus, but they most commonly appear in the maxillary sinus, frequently involving the floor or medial wall of the maxillary sinus. They are usually unilateral, though bilateral cases have been reported. The cysts grow slowly and may rupture spontaneously after reaching a certain size, with cystic fluid draining through the sinus opening. Most cases are asymptomatic, and they are often incidentally discovered during radiological examinations of the sinuses.
Etiology
The condition is caused by mucosal inflammation or allergic reactions, where serous fluid from capillary exudation accumulates in the connective tissue of the submucosa, gradually expanding to form a cyst. The cyst wall consists of sinus mucosa with inflammatory changes, while the cystic fluid is a translucent, pale yellow or yellowish-brown liquid with a tendency to coagulate. A small number of cysts originate from the mucosal mucous glands, which develop thicker cyst walls and contain mucous fluid.
Clinical Manifestations
In most cases, this condition is asymptomatic. Occasionally, there might be a sensation of pressure in the face or a headache in the frontal region, as well as pain in the upper teeth on the affected side. In rare instances, intermittent yellow fluid discharge from the nasal cavity may occur. Some patients exhibit more significant symptoms, which tend to occur intermittently. Symptoms typically subside after the cyst ruptures and yellow, transparent fluid is discharged, but they recur as the cyst reaccumulates fluid. In some cases, maxillary sinus cysts may be a trigger for trigeminal neuralgia.
Diagnosis
Diagnosis is established based on medical history, sinus CT findings, or the aspiration of yellow, transparent fluid during maxillary sinus puncture. Diagnosis may also occur incidentally during routine maxillary sinus surgery. Recurrent, intermittent yellow nasal discharge is strongly indicative of this condition.
Treatment
Most mucosal cysts may rupture spontaneously. Surgical removal is recommended in cases of recurrent episodes. When the cyst is small and asymptomatic, surgery is typically not required. In cases with significant clinical symptoms, surgical intervention may be performed.
Surgical Method
Endoscopic nasal surgery is the preferred approach. For maxillary sinus cysts, the choice of surgical approach depends on the location of the cyst and may involve middle meatus antrostomy, inferior meatal antrostomy, or the pre-lacrimal recess approach. For sphenoid and ethmoid sinus cysts, the same surgical methods as for mucous cysts may be employed. It is recommended to excise the cyst wall as completely as possible or remove the majority of the cyst wall.