Correct Answer: C. Frontal mucocele
A frontal mucocele is a benign, mucus-filled cystic expansion of the frontal sinus that occurs following trauma or chronic sinusitis, causing erosion of the anterior and superior orbital walls. The key discriminating feature here is the 15-year history of trauma (road traffic accident) combined with nonaxial proptosis (typically superior and medial displacement of the globe). On CT, a mucocele appears as a well-defined, expansile lesion with smooth margins, often with bone erosion or remodeling of the frontal sinus walls. The pathophysiology involves obstruction of the frontal sinus ostium post-trauma, leading to accumulation of mucus under pressure, which gradually erodes bone and displaces orbital contents. Unlike acute orbital cellulitis or pseudotumor, mucoceles are chronic, painless, and progress slowly over years. The nonaxial (superior) proptosis is characteristic because the lesion arises from the frontal sinus above the orbit. Indian ENT practice recognizes mucoceles as a delayed complication of head trauma, particularly in patients with inadequately treated or unrecognized frontal sinus fractures. Management typically involves endoscopic marsupialization or external frontoethmoidectomy to restore sinus drainage and prevent further orbital compromise.
Why the other options are wrong
A. Juvenile nasopharyngeal angiofibroma — JNA typically presents in adolescent males with epistaxis, nasal obstruction, and nasopharyngeal mass on endoscopy. It causes axial proptosis (straight forward displacement) due to posterior nasopharyngeal origin, not nonaxial proptosis. JNA has no association with remote head trauma; it arises from the nasopharyngeal roof. CT/MRI shows a hypervascular mass with bowing of the posterior maxilla, not a frontal sinus lesion with bone erosion. B. Pseudotumor of orbit — Orbital pseudotumor (idiopathic orbital inflammation) is an acute or subacute inflammatory condition presenting with pain, chemosis, and rapid onset of proptosis. It has no history of trauma and is not associated with chronic sinus disease. Pseudotumor shows diffuse orbital infiltration on imaging, not a well-defined cystic lesion confined to the frontal sinus with bone erosion. It typically responds to corticosteroids, whereas mucoceles require surgical drainage. D. Frontal meningioma — Meningiomas are intracranial tumors arising from dura, presenting with progressive neurological symptoms (headache, seizures, focal deficits) and axial proptosis from mass effect. They have no association with head trauma 15 years prior. Imaging shows an enhancing dural-based mass, often with hyperostosis, not a mucus-filled sinus cavity with smooth margins and bone remodeling typical of mucoceles.
High-Yield Facts
- Frontal mucocele is a delayed complication of frontal sinus trauma, typically presenting 10–20 years post-injury due to ostial obstruction and mucus accumulation.
- Nonaxial (superior/medial) proptosis is the hallmark of mucocele because the lesion arises from the frontal sinus above and medial to the orbit.
- CT shows expansile, well-defined cystic lesion with smooth margins, bone erosion/remodeling, and intact sinus mucosa lining the cavity.
- Endoscopic marsupialization is the first-line treatment in India, restoring sinus drainage and halting progression; external approach reserved for extensive disease.
- Mucoceles are painless and chronic, distinguishing them from acute orbital cellulitis, pseudotumor, and infectious sinusitis which present acutely with pain and systemic signs.
Mnemonics
MUCOCELE Timing Months to Years post-trauma (typically 10–20 years) → Ostial obstruction → Cystic expansion → Erosion of bone → Lateral/superior displacement of orbit → Endoscopic marsupialization. Nonaxial Proptosis = Sinus Origin Nonaxial (superior/medial) proptosis → think frontal/ethmoid sinus lesion (mucocele, meningocele). Axial proptosis → think retrobulbar mass (cavernous sinus, optic nerve, muscle).
NBE Trap
NBE pairs "head trauma history" with acute complications (fracture, hematoma) to distract from delayed mucocele formation. Students may incorrectly assume trauma 15 years ago is irrelevant, missing the classic temporal relationship. The nonaxial proptosis is the key to ruling out axial lesions (JNA, meningioma).
Clinical Pearl
In Indian trauma centers, frontal mucoceles are an underdiagnosed cause of progressive proptosis in patients with old head injuries. A patient presenting 10–20 years post-RTA with painless, slowly progressive nonaxial proptosis and normal vision should raise suspicion for mucocele; early endoscopic drainage prevents blindness from optic nerve compression and orbital apex syndrome.
_Reference: Booth et al. (Functional Endoscopic Sinus Surgery) Ch. 12; Bhattacharyya et al. (Otolaryngology: Head & Neck Surgery) on mucoceles; Indian ENT standard references (Dhingra's Diseases of Ear, Nose and Throat) Ch. on paranasal sinuses._