Humayun Baig1,2, Jessica Boyle2,3

Purpose: To present a rare case of right external ophthalmoplegia secondary to advanced mucosal melanoma invading the left maxillary sinus. Mucosal melanoma constitutes 1% of melanoma cases and 4% of all head and neck tumours.

Method: A 73-year-old female was referred by her oncologist to a private ophthalmic clinic in Melbourne, Australia regarding sudden onset of complete right ptosis with reduced ipsilateral ocular movements. A two-day history of diplopia was reported before ptosis onset. The patient was diagnosed with mucosal melanoma of the left maxillary sinus in 2014 and underwent palliative radiotherapy. Ophthalmic examination was undertaken.

Results: Best-corrected visual acuities were 6/9 in the right and left eyes. Dilated fundus examination was unremarkable. There was complete right ptosis, reduced right corneal sensation (V1 involvement), and the right pupil was dilated and non-responsive. No proptosis was apparent. Ocular movement testing revealed total ophthalmoplegia of the right eye. Left ocular movements were full.

These findings were inconsistent with the initial diagnosis of mucosal melanoma involving the left maxillary sinus. Repeat MRI of the brain was requested and revealed the tumour to now extend posteriorly into the sphenoid sinus and clivus, and encase the right internal carotid artery and right cavernous sinus. Diplopic symptoms were relieved by the ptosis, therefore no active treatment was recommended.

Conclusion: A rare case of mucosal melanoma and its ocular manifestations is reported. The unusual ophthalmic findings described can be explained by the progressive tumour which initially involved the left paranasal sinuses but eventually traversed the contralateral side.