Ocular Melanoma

Steven H. Lin and Vincent J. Lee

Background

How does intraocular melanoma rank in terms of incidence among the various eye malignancies?

Intraocular melanoma is #1 among primary cancers (#1 overall is ocular mets).

What is the incidence of ocular melanoma in the U.S.? Is there a race predilection?

4 in 1 million (~1,500 to 2,000 cases/yr of ocular melanoma)
Yes. 98% of pts are white.

What is the most common site in the eye where ocular melanomas arise?

Uvea, mostly choroidal (85%) > adnexa (10%) > conjunctiva (5%)

What is the cell of origin for ocular melanoma?

Ocular melanoma arises from uveal melanocytes of the uveal stroma (neural crest origin).

What are the components of the uveal tract?

The choroid, cilary body, and iris comprise the uveal tract.

Name the layers of the choroid from outer to inner.

Layers of the choroid (outer to inner):

Haller layer
Sattler layer
Choriocapillaris
Bruch membrane

What are the basic layers of the globe?

Outer fibrous layer (sclera), middle vascular layer (choroid), and inner nerve layer (retina)

What is the name for the ant termination of the retina?

The ora serrata is the ant termination of the retina.

What region in the retina is particularly important for color vision?

The macula is important for color vision.

Where is the optic disc relative to the macula?

The optic disc is 2 mm medial to the macula (~1.5 mm in diameter).

What are some of the risk factors for developing ocular melanoma?

UV exposure, white, family Hx of ocular melanoma, and personal Hx of cutaneous melanoma

What is the most common chromosomal abnormality seen in ocular melanoma?

Loss of chromosome 3 and amplification of 8q (50%)

What are the histologic subtypes of ocular melanoma, and which carry the best and worst prognosis?

Spindle cell (best), epithelioid (worst), and mixed (if <50% epithelioid histology)

What % of pts with ocular melanoma present with DM at Dx? What is the most common location?

1%–2% present with DM. The liver is the most common site (5%–20% DM rate over 5 yrs).

What are the different ways melanoma can spread within the globe?

Melanoma can spread intraocularly (through the vitreous, aqueous, or along ciliary vessels/nerves); extraocularly (through the optic nerve, transsclerally, vascular tracking), and through extrascleral extension (10%–15%)

What tumor characteristics predict for DM in ocular melanoma? What is the 5-yr mortality rate in these pts?

Epithelioid histology, large tumors, ant location (ciliary body invasion), monosomy 3, scleral penetration, ↑ mitotic rate, ↑ Ki-67, pleomorphic nucleoli, optic nerve invasion, ↑ MIB-1 index, vascular networks of closed vascular loops, extraocular extension

The 5-yr mortality rate is 55%.

What is the long-term (>10-yr) DM rate from ocular melanoma?

50% of ocular melanoma pts develop DMs at 15 yrs.

Workup/Staging

How do pts with ocular melanoma normally present?

Most (one third) pts are asymptomatic. Ocular melanoma is usually found on routine exam; otherwise, pts detect it themselves due to vision loss, scotoma, flashing lights, or pain (rare).

What is the workup for a pt with suspected ocular melanoma?

Suspected ocular melanoma workup: H&P, CBC (LFTs), ophthalmic/funduscopic/slitlamp exam, visual acuity/visual field testing, US (Kretz A-scan, immersion B-scan), fluorescein angiography, MRI, PET/CT to r/o mets

Is Bx commonly done for ocular melanoma?

No. With Bx, there is a potential for tumor seeding. The Dx is made by exam and imaging.

What are simulation lesions?

Simulation lesions are lesions that may look like melanoma, such as nevi, hemangiomas, retinal detachment, age-related disciform lesions, and mets.

What feature does ocular melanoma manifest on standard A-scan US?

An acoustic “quiet” zone (central hypoechoic area) vs. mets or hemangiomas (have higher internal reflectivity)

What features do ocular melanomas exhibit on fluorescein angiography?

On fluorescein angiography, ocular melanomas exhibit a double circulation pattern and fluorescein leakage (appearing as hot spots).

What is the T staging of choroidal/ciliary body melanoma based on the latest AJCC (2009) staging guidelines?

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