Metastatic choroidal melanoma to the ipsilateral orbit 7 years after enucleation

Sir,

Metastasis of choroidal melanoma to the contralateral orbit is rare.¹ Only one case with bilateral orbital involvement has been previously reported.² To our knowledge, we present the first case of choroidal melanoma metastasis to the ipsilateral orbit, 7 years after enucleation.

Case report

In 1993, a 47-year-old man was referred because of a tumour in the right eye. His general history was unremarkable. He had no family history of cutaneous or ocular malignant melanoma or dysplastic naevus syndrome. On examination, the best-corrected visual acuity of both eyes was 1.0 (logmar scale). Fundoscopy showed a prominent pale tumour superotemporal to the fovea. The left eye was normal. Ultrasonography showed a tumour base of 9 × 10 mm² and a thickness of 8 mm. Choroidal excavation was obvious with decreased internal amplitudes in the tumour on the diagnostic A scan. There were no signs of extrascleral extension. General physical examination and laboratory tests were unremarkable. With a diagnosis of primary malignant choroidal melanoma the patient was treated with brachytherapy using a Ruthenium applicator (apical dose: 143 Gy) combined with transpupillary thermotherapy (TTT).³ After 2 years of tumour regression, a vitreous haemorrhage occurred with a complete retinal detachment. The visual acuity of the right eye was reduced to hand movements. In 1995, the eye was enucleated and an Allen-type orbital implant was placed.

Histological examination showed scar tissue and some loose pigment at the site of the irradiated tumour, without evidence of residual melanoma. Extrascleral outgrowth could be excluded. At 5 years after enucleation, the patient developed multiple biopsy-proven metastases in the liver, the diaphragm, skin, and the spine. He received palliative treatment.

In 2002, 7 years after enucleation, he presented with sudden onset of ptosis of the right upper eyelid and poor prosthesis fit (Figure 1). On examination, the prosthesis as well as the orbital implant were displaced inferiorly and anteriorly. The right vertical eyelid fissure was 3 mm and the levator function was 7 mm. There was a mass palpable in the right upper eyelid. Orbital CT-scans revealed two soft tissue lesions. One was located in the anterior part of the superior rectus muscle (Figure 2, top left), the other was localized in the posterior section of the medial rectus muscle and extended into the optic nerve canal (Figure 2, top right, bottom). No informed consent was obtained for diagnostic confirmation. In September 2003, the patient died from carcinomatosis. Regrettably, consent for postmortem examination was not obtained.

Figure 1

Clinical appearance of patient showing ptosis and prosthesis displacement on the right side.

Figure 2

(Top left) Coronal CT-scan showing a mass anteriorly localized in the right superior rectus muscle depressing the Allen implant and the prosthesis. (Top right) Coronal CT-scan demonstrating a posteriorly located mass in the medial rectus muscle. (Bottom) Axial CT-scan showing two lesions in the superior and medial rectus muscle (small orange arrows). Note the tumour extension in to the optic nerve canal (big yellow arrow).

Comment

Metastatic orbital melanoma usually originates from the skin.¹ Nine cases of metastasis of a choroidal melanoma to the contralateral orbit after enucleation have been reported.¹ Massy et al² described an 81-year-old man who developed multiple orbital metastases bilaterally 8 years after enucleation. Our patient developed metastases in two extraocular muscles 7 years after enucleation. Although local recurrence of the choroidal melanoma cannot be ruled out, this seems highly unlikely, because two separate lesions were present and both occurred in the extraocular muscles, which are a predilection site for metastatic melanoma.⁴ In addition, both the sudden onset of blepharoptosis and the histopathology after enucleation, which revealed no extrascleral extension, point to metastasis as main cause. Our case is in agreement with previous reports that melanoma metastasis to the orbit tends to occur in patients that already suffer from widespread metastatic disease.^{4, 5}