Endoscopic Management of a Right Maxillary Sinus Mucocele With Palatal and Medial Wall Erosion

A mucocele is a benign, mucus-filled cystic lesion resulting from obstruction of the sinus ostium, leading to gradual mucus accumulation and remodeling of the surrounding bony walls. A mucocele affecting the maxillary sinus is known as a maxillary sinus mucocele. Although less common than frontal or ethmoidal mucoceles, large maxillary mucoceles may extend to adjacent structures, producing ophthalmic or dental manifestations. In severe cases, they can cause facial swelling, bony erosion, and midfacial disfigurement, sometimes mimicking aggressive or neoplastic pathology. Here, we present a case of a 27-year-old male with a history of multiple sclerosis who presented with right facial swelling, facial pain, nasal obstruction, and nasal discharge. Clinical examination showed a tender, fluctuant swelling over the right maxilla, and computed tomography demonstrated a large expansile cystic lesion occupying the right maxillary sinus. The patient underwent endoscopic marsupialization and resection under general anesthesia, with excellent postoperative recovery. Histopathology demonstrated a cystic cavity lined by attenuated simple squamous epithelium merging with native respiratory mucosa, indicating a maxillary sinus mucocele with an associated odontogenic epithelial component. This case highlights the importance of considering a maxillary sinus mucocele in the differential diagnosis of unilateral facial swelling and nasal obstruction. It underscores the diagnostic challenge it poses when mimicking chronic rhinosinusitis or odontogenic cysts, and emphasizes the crucial role of early radiologic evaluation and multidisciplinary collaboration in achieving accurate diagnosis and preventing complications.