Sinonasal polyps are commonly associated with chronic sinusitis. Prompt and early diagnosis is essential because of the burden of this disease on the patient. This disease negatively affects the quality of life of the patients. Sinonasal polyp should be suspected in patients with chronic sinusitis that is recalcitrant to medical therapy especially in resource-poor centers where endoscopy is not readily available. I present a case of recalcitrant chronic rhinosinusitis with a left ethmoidal polyp which was seen on paranasal sinus computed tomography as a left antral mucous retention cyst. Intraoperative findings showed a polyp arising from the left ethmoidal sinus, extending into the left antrum, mimicking a left antral mucous retention cyst.

Keywords : Left Ethmoidal Polyp, Mucous Retention Cyst, Paranasal Sinus, Chronic Sinusitis.