Small Choroidal Melanoma Revealed by a Large Extrascleral Extension

Orbital extraocular extension of choroidal melanoma is very rare with small melanomas. We report the case of a patient whose small choroidal melanoma was initially overlooked and was revealed by a large extrascleral extension.

A 48-year-old Caucasian woman presented with sudden total visual loss in the right eye. Multicolor imaging of the fundus showed right optic disc edema and an orange and green lesion near the optic disc. The diagnosis of unilateral optic neuritis was made. Magnetic resonance imaging showed an extraocular mass adjacent to the optic nerve; on ultrasound, this mass was acoustically hollow and a small intraocular component was visible.

Choroidal melanoma with a large extrascleral extension was diagnosed (T4eN0M0, stage IIIC according to the AJCC 7th TNM classification, 2010). The size of the extraocular nodule was 13 × 5 mm. Treatment consisted of enucleation followed by adjuvant external beam orbital radiotherapy. Tumor analysis showed a mixed cell type melanoma with monosomy 3. The patient developed liver metastasis 10 months after local treatment.

Extraocular extension of choroidal melanoma can occur with small lesions. Prognosis is generally poor according to AJCC TNM. This case is a reminder that fundus examination may reveal the nature of the mass in some patients with orbital tumors.