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Uveal melanoma

Overview

Uveal melanoma is a cancer (melanoma) of the eye involving the iris, ciliary body, or choroid (collectively referred to as the uvea). Tumors arise from the pigment cells (melanocytes) that reside within the uvea giving color to the eye. These melanocytes are distinct from the retinal pigment epithelium cells underlying the retina that do not form melanomas.

Symptoms - Uveal melanoma

Symptoms can include:

  • A growing dark spot on the iris
  • A change in the shape of the dark circle (pupil) at the center of your eye
  • Poor or blurry vision in one eye
  • Glaucoma
  • Eye pain and redness

Causes - Uveal melanoma

The cause of uveal melanoma is unclear, but UV light is a risk factor. Uveal nevi are common (10% of caucasians), but rarely progress to melanoma.

Prevention - Uveal melanoma

There's no sure way to prevent eye melanoma. While there's little evidence to suggest that ultraviolet (UV) light from the sun may increase the risk of eye melanoma, wearing sunglasses to protect your eyes from UV light can reduce your risk of other eye problems, such as cataracts.

When selecting sunglasses, look for ones that have:

  • Protection against two types of UV light. Two types of UV light can damage your eyes — UVA and UVB. Look for sunglasses that block both types.
  • Uniform tinting. Look for lenses that are uniformly dark. Avoid lenses that seem lighter in some spots and darker in others.
  • Dark lenses. Try the sunglasses on and look into a mirror. If you can clearly see your eyes through the lenses, the sunglasses aren't dark enough.
  • Frames that block light from the side. Some frames, called wraparound frames, are made to block light from the side

Diagnosis - Uveal melanoma

The signs and symptom information on this page attempts to provide a list of some possible signs and symptoms of Uveal melanoma. This medical information about signs and symptoms for Uveal melanoma has been gathered from various sources, may not be fully accurate, and may not be the full list of Uveal melanoma signs or Uveal melanoma symptoms. Furthermore, signs and symptoms of Uveal melanoma may vary on an individual basis for each patient. Only your doctor can provide adequate diagnosis of any signs or symptoms and whether they are indeed Uveal melanoma symptoms

Prognosis - Uveal melanoma

Several clinical and pathological prognostic factors have been identified that are associated with higher risk of metastasis of uveal melanomas. These include large tumor size, ciliary body involvement, presence of orange pigment overlying the tumor, and older patient age.Likewise several histological and cytological factors are associated with higher risk of metastasis including presence and extent of cells with epithelioid morphology, presence of looping extracellular matrix patterns, increased infiltration of immune cells, as well as staining with several immunohistochemical markers.

The most important genetic alteration associated with poor prognosis in uveal melanoma is inactivation of BAP1, which most often occurs through mutation of one allele and subsequent loss of an entire copy of Chromosome 3 (Monosomy 3) to unmask the mutant copy. Because of this function in inactivation of BAP1, monosomy 3 correlates strongly with metastatic spread Where BAP1 mutation status is not available, gains on chromosomes 6 and 8 can be used to refine the predictive value of the Monosomy 3 screen, with gain of 6p indicating a better prognosis and gain of 8q indicating a worse prognosis in disomy 3 tumors. In rare instances, monosomy 3 tumors may duplicate the BAP1-mutant copy of the chromosome to return to a disomic state referred to as isodisomy. Thus, isodisomy 3 is prognostically equivalent to monosomy 3, and both can be detected by tests for chromosome 3 loss of heterozygosity. Monosomy 3, along with other chromosomal gains, losses, amplifications, and LOH, can be detected in fresh or paraffin embedded samples by virtual karyotyping.

The most accurate prognostic factor is molecular classification by gene expression profiling of uveal melanomas. This analysis has been used to identify two subclasses of uveal melanomas: class 1 tumors that have a very low risk of metastasis and class 2 tumors that have a very high risk of metastasis. Gene expression profiling outperforms all of the above-mentioned factors at predicting metastatic spread of the primary tumor, including monosomy 3.

Treatment - Uveal melanoma

The treatment protocol for uveal melanoma has been directed by many clinical studies, the most important being "The Collaborative Ocular Melanoma Study" (COMS). The treatment varies depending upon many factors, chief among them, the size of the tumor. Primary treatment can involve removal of the affected eye (enucleation); however, this is now reserved for cases of extreme tumor burden or other secondary problems. Advances in radiation therapies have significantly decreased the number of patients treated by enucleation in developed countries. The most common radiation treatment is plaque brachytherapy, in which a small disc-shaped shield (plaque) encasing radioactive seeds (most often Iodine-125, though Ruthenium-106 and Palladium-103 are also used) is attached to the outside surface of the eye, overlying the tumor. The plaque is left in place for a few days and then removed. The risk of metastasis after plaque radiotherapy is the same as that of enucleation, suggesting that micrometastatic spread occurs prior to treatment of the primary tumor. Other modalities of treatment include transpupillary thermotherapy, external beam proton therapy, resection of the tumor, Gamma Knife stereotactic radiosurgery or a combination of different modalities. Different surgical resection techniques can include trans-scleral partial choroidectomy, and transretinal endoresection.

Resources - Uveal melanoma

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