In carcinoma of the maxillary sinus, Ohngren's line is drawn from the medial canthus to the angle of the mandible. Tumours arising above this plane carry a significantly poorer prognosis chiefly because they involve:
- A The alveolar process and hard palate
- B The orbit, ethmoids, and skull base structures ✓
- C The buccinator muscle and overlying skin
- D The pterygoid plates and infratemporal fossa
Correct answer: B. The orbit, ethmoids, and skull base structures
Explanation
Ohngren's line divides the maxillary antrum into a posteroinferior infrastructure and an anterosuperior suprastructure. Suprastructure tumours lie adjacent to the orbit, ethmoid labyrinth, and skull base, allowing early spread to these critical structures and making complete resection difficult, hence the poor prognosis. Infrastructure tumours invade the palate and alveolus, producing dental symptoms that often lead to earlier detection. Pterygoid invasion defines advanced disease but is not the reason the line was drawn.
Reference: Dhingra's Diseases of Ear, Nose and Throat, 8th ed.
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Written and medically reviewed by the StethoPrep medical team.