Uveal melanoma overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]
Overview
Uveal melanoma is a cancer of the eye involving the iris, ciliary body, or choroid. Uveal melanoma arise from melanocytes in the uvea. Uveal melanoma is a rare disease, but the most common primary intraocular malignancy. Iris melanomas are less common than choroidal melanomas. Uveal melanoma may be classified into several subtypes based on their location, based on ophthalmoscopic examination and based on the cell type. According to the Callender classification, there are four subtypes of uveal melanoma based on the cell type. Genes involved in the pathogenesis of uveal melanoma include GNAQ, GNA11, and BAP1. Uveal melanoma is caused by a mutation in the DNA. The incidence of uveal melanoma in the United States is approximately 0.43 per 100,000 individuals. The majority of uveal melanoma cases are reported in Europe and United States. The incidence of uveal melanoma increases with age; the median age at diagnosis is 60 years. Males are more commonly affected with uveal melanoma than females. Uveal melanoma commonly affects individuals older than twenty years of age. Caucasians are more commonly affected with uveal melanoma than Africans. Common risk factors in the development of uveal melanoma are cutaneous and iris nevi, host pigmentation factors, ultraviolet light exposure, caucasian race, and certain inherited skin disorders such as dysplastic nevus syndrome and ocular melanocytosis. If left untreated, 50% of patients with uveal melanoma may progress to develop metastasis. Common complications of uveal melanoma include glaucoma, vision loss, and metastasis. Prognosis is generally good for patients with iris melanoma, and the 10 year-survival for iris melanoma is approximately 95 percent and for ciliochoroidal tumors is 77 percent respectively. Symptoms of uveal melanoma include eye pain, eye redness, loss of peripheral vision, poor or blurry vision in one eye, a dark spot on the iris, flashing lights, floaters, and symptoms of glaucoma. The optimal therapy for uveal melanoma depends on the size of the tumor. The various treatment modalities for uveal melanoma include enucleation, plaque brachytherapy, external beam proton therapy, transupillary thermotherapy, Gamma Knife stereotactic radiosurgery, and resection of the tumor.
Historical Perspective
Uveal melanoma was first discovered by two Scottish surgeons, Allan Burns (1781–1813) and James Wardrop (1782–1869). Allan Burns described the first patients with uveal melanoma, Mrs Scot who had painless blindness in one eye and an opacity behind the lens.
Classification
Uveal melanoma may be classified according to cell type into 5 subtypes: Spindle A, spindle B, epitheliolid, mixed, and necrotic. Uveal melanoma may also be classified according to its location into 2 types, anterior uveal melanoma which contain iris melanoma, and posterior uveal melanoma which contains ciliary body melanoma and chroidal melanoma.
Pathophysiology
It is understood that uveal melanoma is the result of genetic mutations. Activating mutations in GNAQ or GNA11, genes encoding for G protein alpha subunits. These mutations lead to activation of downstream signaling pathways including the MAPK pathway in uveal melanoma. Inactivating somatic mutations are present in the gene encoding BRCA1-associated protein 1 (BAP1) on chromosome 3p21.1. The mutations in the gene BAP1 are strongly linked to metastatic spread and patient survival. Conditions associated with uveal melanoma include ocular nevi, impaired immune system, pregnancy, and trauma. On microscopic histopathological analysis, we have 5 subtypes according to cell type into: Spindle A, spindle B, epitheliolid, mixed, and necrotic.
Causes
Uveal melanoma is caused by a mutation in the DNA.
Differential Diagnosis
Uveal melanoma must be differentiated from retinoblastoma, coats disease, persistent fetal vasculature, astrocytic hamartoma, retinopathy of prematurity, ocular toxocariasis, familial exudative vitreoretinopathy, norrie’s disease, and coloboma.
Epidemiology and Demographics
The incidence of uveal melanoma in the United States is approximately 0.43 per 100, 000 individuals. The incidence of uveal melanoma is approximately .53 to 1.09 cases per 100, 000 individuals worldwide. The incidence of uveal melanoma increases with age; the median age at diagnosis is 70 years. Males are more commonly affected with uveal melanoma than females. The incidence of uveal melanoma in males and females is approximately 0.49 and 0.37 per 100,000 individuals respectively. Uveal melanoma usually affects individuals of the caucasians race.
Risk Factors
Common risk factors in the development of uveal melanoma include advanced age, male gender, white race, genetic, ocular nevi, pregnancy, impaired immune system, light colored iris, sunlight exposure, and trauma.
Screening
According to the United States Preventive Services Task Force, screening for uveal melanoma is not recommended.
Natural History, Complications and Prognosis
If left untreated, 50% of patients with uveal melanoma may progress to develop metastasis. Common complications of uveal melanoma include glaucoma, vision loss, and metastasis. Prognosis is generally good for patients with iris melanoma, and the 10 year-survival for iris melanoma is approximately 95 percent and for ciliochoroidal tumors is 77 percent respectively.
Diagnostic Study of Choice
There is no single diagnostic study of choice for the diagnosis of uveal melanoma, but uveal melanoma can be diagnosed based on ophthalmologic examination and imaging.
History and Symptoms
A positive history of pre-existing iris nevus which increased in size, eye pain, visual loss, blurred vision, floaters, age between 50_70 years old, male gender, white race, pregnancy, impaired immune system, light colored-irides, sunlight exposure, trauma, and fluorescent lighting exposure is suggestive of uveal melanoma. The most common symptoms of name] include ,eye pain, blurred vision, eye redness, loss of peripheral vision, poor or blurry vision in one eye, a dark spot on the iris, seeing flashing lights, and floaters.
Physical Examination
Patients with uveal melanoma usually appear normal. Physical examination of patients with uveal melanoma is usually remarkable for ophthalmologic findings of melanoma.
Laboratory Tests
Some patients with uveal melanoma may have elevated liver enzyme level, which is usually suggestive of metastasis.
Electrocardiogram
There are no ECG findings associated with uveal melanoma.
X Ray
There are no x-ray findings associated with uveal melanoma.
Ultrasound
Ultrasound may be helpful in the diagnosis of uveal melanoma. Findings on an ultrasound suggestive of uveal melanoma include low reflectivity, vascularity inside the tumor, and acoustic hollowing. it can differentiate ciliary body cyst from tumor in lesions larger than 3 mm.
CT Scan
CT scan may be helpful in the diagnosis of uveal. Findings on CT scan suggestive of uveal melanoma include elevated mushroom shaped lesions, hyper-dense, and contrastenhancement.
MRI scan
MRI may be helpful in the diagnosis of uveal melanoma. Findings on MRI suggestive of uveal melanoma include high intensity mass lesion (due to melanin and hemorrhage) on T1, and low intensity mass lesion on T2. The lesion enhances with gadolinium.
Other Imaging Studies
PET scan, ultrasound biomicroscopy, optical coherence tomography, color fundus photography, fluorescein angiography, indocyanine green angiography, transillumination, and photography may be helpful in the diagnosis of uveal melanoma.
Other Diagnostic Tests
Biopsy may be helpful in the diagnosis of uveal melanoma.
Medical therapy
The optimal therapy for uveal melanoma depends on the size of the tumor. The various treatment modalities for uveal melanoma include enucleation, plaque brachytherapy, external beam proton therapy, transupillary thermotherapy, Gamma Knife stereotactic radiosurgery, and rection of the tumor.
Surgical therapy
Surgery is the mainstay of treatment for uveal melanoma. The following types of surgery may be used resection, enucleation, and exenteration.
Primary Prevention
There is no established method for prevention of uveal melanoma.
Secondary Prevention
There are no established measures for the secondary prevention of uveal melanoma.