Case Report
Dilated Exam Reveals Choroidal Tumor

Differential Diagnosis of Choroidal Melanoma

This patient's complaints of blurred vision led to a comprehensive workup and treatment of the malignant mass.

by Neeraj Bindal, O.D. and Kevin Jackson, O.D.

A 49-year-old white male presented complaining of constant "blurry, cloudy and shadowy vision" in his right eye for three weeks. He also said that his pupils were occasionally of unequal size. His last dilated eye exam was 20 years ago.

This patient's ocular and systemic histories were unremarkable. His father had diabetes, and a grandfather had glaucoma. The patient was not taking any medications and had no known drug allergies.

Diagnostic Data
Best-corrected visual acuity was 20/15 O.U. Versions were smooth, with full eye movements. Color vision on pseudo-isochromatic plates was 15/15 O.D., 14/15 O.S.

Pupils were 4mm O.D., 5mm O.S. Pupillary responses to light were brisker in the left eye (grade 3+) than in the right (grade 2+). We noted a trace afferent pupillary defect in the right eye.

Confrontation fields showed a defect on finger-counting in the temporal field of the right eye. The left eye was full to finger counting.

IOP was 12mm Hg in the right eye, 16mm Hg in the left. The slit lamp exam was unremarkable.

A full-field, 120-point screening test revealed mid-temporal and mid-inferior defects in the right eye. The left eye was normal.

A dilated fundus exam revealed an 8mm x 8mm subretinal mass in the right eye. The mass was located nasally and encroached the optic nerve. The elevation was pale yellow, with scattered superficial darker orange granules. The retinal vessels and macula appeared normal. The left fundus was normal.

A dilated fundus exam revealed an 8mm x 8mm subretinal mass in the right eye (left).  Proton beam treatment arrested the growth of the melanoma.

We consulted retinal specialists within our clinic. We also conducted A- and B-scan ultrasonography. This outlined the mass, giving a thickness of 5mm with low internal reflectivity.

We then sent the patient for a complete physical exam, which included complete blood count, liver enzymes and chest X-ray. All findings were normal, ruling out significant metastasis.

An orbital MRI detailed the posterior chamber mass with a broad-based attachment to the retina and adjacent to the optic disc. The optic nerve did not seem to be infiltrated, and no extrascleral extension was apparent. The retrobulbar fat and extraocular muscle appeared uninvolved.

Diagnosis
The visual field, ultrasound and fundus appearance indicated a choroidal tumor. Fine-needle aspiration biopsy performed a few days later histologically confirmed our diagnosis: amelanotic epithelioid choroidal melanoma.

Treatment and Follow-up
We educated the patient about the diagnosis and arranged for an evaluation with an ophthalmic oncologist.

An orbital MRI detailed the posterior chamber mass with a broad-based attachment to the retina.

The patient returned to the clinic 13 days later for a follow-up. Visual acuity was now 20/40-2 O.D. The fundus exam now revealed signs of a small hemorrhage adjacent to the tumor and mild vitreous haze.

The retinal specialist and oncologist evaluated the blood test and radiology results, and educated the patient about treatment options, including enucleation. After further counseling by several ophthalmic oncologists, the patient elected to undergo charged-particle radiation to preserve his eye.

Seven months after the proton beam treatment, the growth of the melanoma has been arrested. The maximum thickness of the tumor has decreased, indicating some shrinkage. As of yet, no anterior segment complications have manifested. Unfortunately, the patient now has no light perception in that eye. He is being closely followed.

Discussion
Intraocular tumors comprise a broad spectrum of benign and malignant lesions that can lead to vision loss and even death. These tumors can be classified into three categories based on histology: neuroblastic (e.g., retinoblastoma), melanocytic (e.g., choroidal melanoma) and metastatic (e.g., metastatic carcinoma).¹

Melanotic lesions are the most common primary intraocular tumors. There are two categories of lesions: benign nevi and malignant melanomas. Race is a strong risk factor, with both occurring 15 times more often in whites than in blacks.² While a benign choroidal nevus is a common fundus finding, a malignant choroidal melanoma is only seen in six cases per million.³ Choroidal tumors typically manifest in patients in their early 60s.

Other risk factors for choroidal tumors may include genetic predisposition, light-colored irides and ocular melanocytic conditions such as melanosis oculi and oculodermal melanocytosis.⁴

You must differentiate a benign nevus from a malignant one, given the major differences in their treatment and prognosis. You also must differentiate choroidal melanomas from other lesions (see Differential Diagnosis of Choroidal Melanoma).¹

Choroidal melanomas are often categorized by cell type and size, both of which have been shown to correlate with survival after enucleation.¹ There are two cell types: spindle cells and epithelioid. Spindle cell tumors have a prognosis of 75 percent survival at five years. However, the survival rate drops to 40 percent for mixed spindle and epithelioid tumors, and 30 percent for pure epithelioid.² Sizes greater than 10mm in diameter have been demonstrated in many studies to increase mortality.⁵

When you suspect choroidal melanoma, a complete workup is necessary. Binocular indirect ophthalmoscopy or slit lamp exam is usually the primary route of discovery of these lesions. Using a red-free filter, you can differentiate choroidal from RPE pigmentation, as pigmentation will fade under red-free illumination. The workup of these patients may also include:

• Perimetry. This can help you distinguish between nevi and melanomas. Nevi rarely result in visual field defects, while melanomas always result in defects.¹

• Photography. This is valuable for documentation and followup.

• Ultrasound. This can help you differentiate intraocular masses and determine the size and depth of the mass. B-scan ultrasonography aids in determining the size, shape and position of intraocular tumors, while A-scan ultrasonography assesses a lesion's internal reflectivity and vascularity.¹ Choroidal melanomas with choroidal excavation demonstrate low to moderate reflectivity.⁶

• Fluorescein angiography. This illuminates the independent circulation that develops with a tumor, confirming the nature of the mass. Fluorescein angiography aids most in differentiating a choroidal hemorrhage (hypofluorescence) from a choroidal melanoma (hyperfluorescence).¹

• Radiological studies. An orbital MRI lets us see the mass to determine if there is extrascleral extension. An MRI series is useful in screening for metastasis to other organs.

• Biopsy. Biopsies provide an unequivocal diagnosis by cell type.³

• Blood work and a comprehensive physical exam.⁶ Blood work, including serum levels of liver enzymes, provides evidence of metastasis.

Management of posterior uveal melanomas is controversial. Some clinicians consider enucleation the treatment of choice, while others believe it may actually increase metastatic spread.³ The death rate peaks at two years after surgery, according to one study.⁷ Other therapeutic approaches include:

• Observation. In certain instances, such as choroidal nevi, observation may be all that's indicated.¹

• Photocoagulation. Although used less often today, it can be effective in treating small melanomas that do not involve the disc margin and are at least 3mm from the foveola.⁸

• Radiation therapy. One form of therapy involves applying a radioactive plaque to the sclera behind the lesion. This offers a high dose of radiation to the tumor, but minimizes radiation to adjacent tissues.⁹ A radioactive cobalt plaque was considered for this patient, but the tumor's involvement with the optic nerve head would have made the application of the plaque too difficult and less effective.

A second option is charged-particle radiation. This requires suturing tantalum clips outlining the margins of the tumor, followed by proton-beam radiation a few days later. This method is effective in treating choroidal and ciliary body melanomas. Unfortunately, the radiation sometimes causes the anterior segment structures the beam passes through to begin to slowly degenerate.¹⁰ Complications include dry eyes, loss of facial sensation, cataracts and damage to other tissues.

• Surgical excision. Excisions have been very successful, but the surgical techniques can be quite difficult.¹ There is a risk that melanoma cells can disseminate into the rest of the body, causing more harm. So, this procedure is rarely performed.

Choroidal nevi are a common finding, and most will never become cancerous. Choroidal melanoma, although rare, is the most common primary intraocular tumor. The prognosis for a patient with a choroidal melanoma is poor; many die within five years secondary to metastasis.¹

Had this patient's condition been diagnosed sooner, his vision might have been saved. We cannot over-emphasize the importance of managing choroidal nevi by photos and close followup, and being able to distinguish benign lesions from malignant ones. Your patient's vision and, more importantly, his or her life depend on accurate diagnosis and timely referral.

Dr. Bindal practices in the Washington, D.C., area. Dr. Jackson practices at the National Naval Medical Center in Bethesda, Md. The authors thank Helena Arteta for the slides.

1. Torczynski E. American Academy of Ophthalmology basic and clinical science course. 1997;4:178-9, 186-91, 230-6, 242-55.
2. Spalton DJ, Hitchings RA, Hunter PA. Atlas of Clinical Ophthalmology. Philadelphia: J.B. Lippincott Co.; 1991:9.1-9.18
3. Cymbor MJ, Check JM. Choroidal melanoma: a review and case report. J Am Optom Assoc 1998;69(10): 656-65.
4. Gonder JR, Shields JA, Albert DM. Uveal malignant melanoma associated with ocular and oculodermal melanocytosis. Ophthalmology 1982;89: 953-60.
5. Johnson RN. Choroidal and Ciliary Body Malignant Melanoma, San Francisco: Retina Research Fund; 1993:85.
6. Cullom RD, Chang B. The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease, ed. 2. Philadelphia: J.B. Lippincott, 1994:177-79.
7. Meredith TA. Choroidal melanoma: diagnosis and management. Am J Ophthalmol 1998;125(6):865-7.
8. Tasman W, Jaeger EA. Duane's Clinical Ophthalmology. Philadelphia: J.B. Lippincott Co., 1994;Ch.68:1-9.
9. Finger PT. Radiation therapy for choroidal melanoma. Surv Ophthalmol 1997;42(3):215-32.
10. Park SS, Walsh SM, Gragoudas ES. Visual-field with proton beam irradiation for peripapillary choroidal melanoma. Ophthalmology 1996;103(1):110-6.
11. Zhao DY, Gunduz K, Shields CL, Shields JA. Choroidal melanoma-associated retinal and retinal pigment epithelial changes. Journal of Ophthalmic Nurs Technol 1998;17(3):110-4.
12. Pau H. Differential Diagnosis of Eye Diseases. New York: Thieme Medical Publishers Inc.; 1988:264-6.

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Differential Diagnosis of Choroidal Melanoma ^1,6,11,12

Here are lists of ocular signs of choroidal melanoma and other masquerading conditions.

Choroidal melanoma
• Elevated, dome-shaped subretinal mass.
• Pigmentation varies from dark brown to completely amelanotic.
• Some tumors erupt through Bruch's membrane. Results in mushroom-like appearance.
• Prominent clumps of orange pigment (lipofuscin) at the level of the retinal pigment epithelium (RPE).
• Serous detachment of the sensory retina is often observed.
• Rarely angle closure glaucoma due to lens-iris displacement and iris rubeosis.

Choroidal nevi
• Typically flat or minimally elevated.
• Slate-gray color, indistinct borders.
• May have overlying RPE disturbance, serous detachment, drusen and choroidal neovascularization membranes.
• Small and flat nevi (less than 10mm in diameter and 2mm in depth) have a 5 percent chance of exhibiting growth in five
years. Larger and elevated lesions associated with RPE changes and subretinal fluid have a 15 percent chance.

Metastatic carcinoma
• Flat to slightly elevated.
• Cream to light brown in color.
• May consist of more than one focal circumscribed area or may be bilateral.
• Patients usually have a history of cancer.

Choroidal hemangiomas
• Often appear as a reddish-orange tumor (commonly referred to as "catsup fundus").
• Densely vascular.

Disciform macular lesions
• Typically bilateral.
• Associated with extensive exudate.

Congenital hypertrophy of the RPE
• Well-defined, flat, darkly pigmented lesion.
• Ranges from 1 to 10 disc diameters.
• Often grows but will not become malignant.

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