Orbital Extension of an Unsuspected Choroidal Melanoma Presumably through an Aqueous Tube Shunt.

AIMS: To report a patient with unrecognized small macular melanoma, who gradually developed neovascular glaucoma that was treated with an Ahmed valve. We presume that tumor cells gained access to the orbit through this aqueous drainage device.

METHODS: The medical records pertaining to 5 different centers, the results of imaging studies, the clinical course of the patient and histopathological findings were retrospectively reviewed.

RESULTS: A 61-year-old man presented with a blind and painful proptotic right eye. Retinal hemorrhage had been suspected 3 years earlier and followed accordingly thereafter. Yearly performed MRI studies demonstrated the steady growth of the hemorrhagic lesion/tumor. Meanwhile, he developed neovascular glaucoma first treated unsuccessfully with cyclocryotherapy then with implantation of an Ahmed valve. Right proptosis became evident within a year, and a final MRI study revealed a large retrobulbar mass. Orbital exenteration was performed and histopathological examination showed intraocular and orbital epithelioid cell melanoma. Tumor cells were also found within the reservoir of the Ahmed valve. The patient died of widespread metastases 1 year later.

CONCLUSIONS: Ahmed valve implantation in an eye with unsuspected macular choroidal melanoma may ultimately be associated with extraocular extension and orbital tumor formation.