45-year-old male presented with decreased peripheral vision of two-year duration
Denied flashing lights, floaters or curtains
VAcc: 20/20; 20/20
Pupils: RR OU, no RAPD
IOP: 14; 15
EOM: Full OU
Juxtapapillary choroidal melanoma
Hyperplasia of the RPE
Combined hamartoma of the retina and RPE
Adenoma of RPE
Fluorescein angiogram was performed to further characterize the lesion (Figure 3)
Humphrey visual field (HVF 30-2) was also obtained (Figure 4) as the patient reported decreasing peripheral vision. In addition, visual field changes have been reported with the most common visual field defect being an enlarged blind spot in approximately 75 to 90 percent of patients with melanocytoma.
Melanocytoma (magnocellular nevus) is a benign tumor considered to be a variant of a melanocytic nevus
The pathogenesis is unknown but it is thought to be either an acquired lesion or a congenital lesion that may start off amelanotic and acquire dense pigmentation with age
The patient was followed up with yearly dilated fundus examination with ancillary fundus photography and B-scan ultrasonography to document the dimensions of the lesion.
There are no treatments available to prevent growth of a melanocytoma. Patients are examined at least yearly to ensure there is no growth. More frequent examinations are warranted if there is documented growth with suspicion for possible transformation into a malignant melanoma.
Prognosis and Future Directions
Majority of melanocytomas do not grow or cause visual symptoms. However, a mild decrease in visual acuity can occur in around 26 percent of patients secondary to retinal exudation, subretinal fluid or optic disc edema.
Severe vision loss is extremely rare, but may occur secondary to a central retinal vein occlusion, tumor necrosis or malignant transformation.
10 to 15 percent of melanocytomas grow over years. An initial thickness ≥ 1.5mm predicts future growth.
Malignant transformation can occur in 1 to 2 percent of cases. Patients typically present with a progressively growing lesion that is associated with decreasing visual acuity.
Other etiologies for a growing melanocytoma include a complication of tumor necrosis that occurs when the melanocytoma outgrows its vascular supply. In addition, a juxtapapillary melanoma needs to be considered in a growing lesion.
MRI can be helpful in determining extent of retrolaminar extension of the lesion especially when suspecting transformation to choroidal melanoma and also aid in the diagnosis of complications of melanocytoma such as tumor necrosis.
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Jesse L. Berry, MD, Assistant Professor of Clinical Ophthalmology and Assistant Director of Ocular Oncology, email@example.com