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Editor,—Conservation of the eye and vision in patients with juxtapapillary choroidal melanoma is still a challenge. Both plaque radiotherapy and proton beam radiotherapy tend to cause optic neuropathy, which is associated with disc and iris neovascularisation, vitreous haemorrhage, and neovascular glaucoma. These complications can also occur after phototherapy, which is less effective than radiotherapy at destroying the deeper parts of the tumour. Transscleral local resection of posterior tumours is especially difficult with tumours extending close to the optic disc and is associated with an increased incidence of local tumour recurrence. For these reasons, techniques have been developed for removing posterior choroidal melanomas transretinally, using standard vitrectomy equipment. In a previous report, eight out of 52 cases received secondary photocoagulation for possible tumour recurrence at the margins of the surgical coloboma and one enucleated eye was found to have microscopic tumour deposits within the coloboma.We report a case of intrascleral tumour recurrence.
A 40 year old man presented with a 6 month history of photopsia. He was found to have a choroidal melanoma in the right eye and referred for conservative treatment. On examination, the vision was 6/4 with each eye. The tumour was pigmented and located inferiorly, extending to within two disc diameters of the fovea and optic disc margin (Fig 1). Approximately 40% of the retina was detached. On ultrasonography, the tumour had basal dimensions of 12.0 mm by 11.7 mm and a thickness of 4.8 mm (Fig 2). The left eye was healthy. Full systemic assessment revealed no other disease.
Transretinal “endoresection” was performed in July 1994. The procedure involved three port vitrectomy, retinectomy over the tumour, endodiathermy to bleeding points, endolaser photocoagulation applied to the margins and the bed of surgical coloboma and fluid-gas-silicone exchange. Histological examination showed the melanoma to be of mixed, spindle, and epithelioid cell type. In September 1994, the eye was settling well, except for an amelanotic choroidal swelling, which was noted adjacent to the inferonasal margin of the coloboma. This was believed to consist of a bubble of silicone oil in the suprachoroidal space although the possibility of recurrent melanoma could not be excluded clinically. There was also a localised tractional retinal detachment caused by vitreous bands.
Vitreoretinal surgery was performed, with release of the vitreous traction and excision of the retina and choroid over the swelling. This procedure confirmed that the tumour consisted of a bubble of silicone oil beneath the choroid. The procedure also included endolaser photocoagulation and silicone-gas exchange. The eye nevertheless developed retinal detachment with proliferative vitreoretinopathy and cataract. In December 1994, further surgery was performed, which consisted of phacoemulsification, removal of epiretinal membrane, 180 degree retinectomy, endolaser photocoagulation, and silicone oil fill.
In April 1995, the retina was flat with an epiretinal membrane covering the inferior margin of the coloboma and a fibrovascular scar partially obscuring the optic disc. It was decided that the silicone oil should be left in place because of the high risk of retinal detachment. When reviewed in February 1999, the vision was hand movements and there was band keratopathy, which precluded ophthalmoscopy. Enucleation was performed because it was not possible to screen the eye adequately for local tumour recurrence. At the time of surgery, an extraocular tumour nodule was noted medial to the optic nerve. The tumour nodule measured approximately 8 mm by 6 mm.
Pathological examination showed the recurrent tumour to be of mixed, spindle, and epithelioid cell type. The tumour appeared to arise within the sclera because of the way in which it was encapsulated by the scleral lamellae. The presence of nerve tissue within the tumour suggested that the melanoma had entered the sclera along a channel for a ciliary nerve. Posteriorly, the tumour had broken through the sclera into the orbit.
To our knowledge, this is the first report of intrascleral recurrence of choroidal melanoma after transretinal endoresection. The tumour probably survived the surgery and phototherapy because it had invaded a scleral canal adjacent to the optic nerve.
It is known that intrascleral tumour deposits can survive after phototherapy or transscleral local resection of choroidal melanoma. In the present case, the adjunctive phototherapy after completion of the tumour resection was either of insufficient power or was not applied to the area where the scleral invasion had taken place. A more effective method of eliminating residual intrascleral tumour would have been to administer adjunctive plaque radiotherapy, which is routine after transscleral local resection in some centres. In the present case, however, this would probably have caused optic neuropathy.
Recurrent tumour after transscleral local resection is associated with an adverse prognosis for survival. It is not known, however, whether the recurrence is the source of metastasis or merely an indicator of tumour aggression.
Further follow up studies are required to determine the incidence of intrascleral tumour recurrence after endoresection of choroidal melanoma.