Sudden‐onset projectile rhinorrhea from the right nostril

Abstract Background Paranasal sinus retention cysts are non‐neoplastic psuedocysts that accumulate nasal fluids. Since most of these cysts are incidentally diagnosed and may even diminish spontaneously, no further diagnosis or therapies are needed for most patients. In contrast, when an abrupt, unilateral, watery nasal discharge is noticed, cerebrospinal fluid (CSF) rhinorrhea should be suspected, which is a true “red flag sign,” since ignored CSF rhinorrhea may be fatal. Case Report Herein we report a case of a 42‐year‐old male with an acute, unilateral, profusely projectile serous rhinorrhea without any trauma or sinonasal surgery history. Following an urgent computed tomography, no skull base abnormalities were seen, ruling out the possibility of CSF rhinorrhea. However, a “ruptured” retention cyst in the maxillary sinus was noticed. Thus, it was concluded that the patient’s projectile unilateral serous rhinorrhea was due to a rupturing of the retention cyst in the affected maxillary sinus. The patient remained asymptomatic afterwards, negating the surgical removal or further follow‐up visits. Conclusion While the majority of paranasal sinus retention cyst cases are symptomless, spontaneous rupture of these cysts may take place and result in a sudden and vigorous release of nasal secretions, mimicking CSF rhinorrhea, as seen in our case.