Ocular melanoma
What is it?
Ocular melanoma is a tumor that:
- originates from melanocytes in the uvea and develops inside the eyeball;
- originates from melanocytes in the conjunctiva and develops outside the eyeball.
There are 2 types of ocular melanoma:
- Uveal melanoma that can originate from the iris, ciliary bodies or posterior choroid. It is the most frequent primary intraocular malignant tumor of adulthood; it tends to grow both inside the eyeball, invading and disorganizing intraocular tissues, and outside, infiltrating the sclera and orbital tissues. Uveal melanoma distantly metastasizes solely by the hematogenous route due to absence of lymphatic vessels at the bulbar level.
- Conjunctival melanoma originating from and growing in the conjunctiva. In both cases (conjunctiva and uveal), growth may occur within the orbit. It is extremely rare (less than 2% of all ocular malignancies), with an incidence of 0.024 to 0.052 new cases per 100,000 population, which is about 1/40th that of uveal melanomas. The pathogenesis of this tumor has always been a source of controversy; it is currently considered to originate in 75% of cases from a primary acquired melanosis (PAM), and in the remaining 25% from a pre-existing or de novo conjunctival nevus.
Causes and risk factors
The primary risk factors for melanoma are associated with age and skin pigmentation. Specifically, the incidence of melanoma rises from African countries, where it is lower, to Northern European countries, where it is significantly higher.
Which are the symptoms?
These melanomas are often asymptomatic. In uveal melanoma, vision disturbances prevail, while in conjunctival melanoma, a dark spot in the white conjunctiva appears to the patient.
How is it diagnosed?
The differential diagnosis between conjunctival melanoma and other pigmented lesions, such as benign nevi, melanosis, and melanocytosis, as well as pre-cancerous conditions like primary acquired melanosis, primarily relies on clinical history, the morphology of the lesion, and biopsy results.
The diagnosis of uveal melanoma, on the other hand, is essentially clinical. Differential diagnosis with other uveal pigmented lesions (nevus, melanocytoma, retinal pigment epithelium hypertrophy, choroidal hemorrhage, neovascularization, and so on) is based on ophthalmoscopic evaluation by an experienced ophthalmologist.
Additional instrumental examinations that may be utilized include fluorescence and/or indocyanine green angiography, as well as ocular A/B scans.
How is it treated?
There are no specific screening programs other than eye examinations.
Where do we treat it?
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