Chorioid melanoma

Malignant tumors of the choroid are mainly represented by melanomas.

There are three possible mechanisms of development of choroidal melanoma: occurrence as a primary tumor - de novo (most often) against the background of a previous choroidal nevus or existing oculodermal melanosis. Choroidal melanoma begins to develop in the outer layers of the choroid and, according to the latest data, is represented by two main cell types: spindle cell A and epithelioid. Spindle cell melanoma metastasizes in almost 15% of cases. The frequency of metastasis of epithelioid melanoma reaches 46.7%. Thus, the cellular characteristics of uveal melanoma are one of the determining factors of prognosis for life. More than half of melanomas are localized beyond the equator. The tumor, as a rule, grows as a solitary node. Usually, patients complain of deterioration of vision, photo- and morphopsia.

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Symptoms of Choroidal Melanoma

In the initial stage, choroidal melanoma is represented by a small brown or dark gray lesion 6-7.5 mm in diameter, on the surface and around which drusen (keloid bodies) of the vitreous plate are visible. Brush-like cavities in the adjacent retina are formed as a result of dystrophic changes in the pigment epithelium and the appearance of subretinal fluid. Orange pigment fields found on the surface of most melanomas are caused by the deposition of lipofuscin grains at the level of the retinal pigment epithelium. As the tumor grows, its color may become more intense (sometimes even dark brown) or remain yellowish-pink, non-pigmented. Subretinal exudate appears when choroidal vessels are compressed or as a result of necrobiotic changes in a rapidly growing tumor. An increase in the thickness of the melanoma causes dystrophic changes in the Bruch's membrane and the pigment epithelium of the retina, as a result of which the integrity of the vitreous plate is disrupted and the tumor grows under the retina - the so-called mushroom-shaped form of melanoma is formed. Such a tumor usually has a fairly wide base, a narrow isthmus in the Bruch's membrane and a spherical head under the retina. When the Bruch's membrane ruptures, hemorrhages may occur, which are the cause of an increase in retinal detachment or its sudden appearance. With juxtapapillary localization of melanoma, subretinal exudation in some cases causes congestion in the optic nerve disk, which in non-pigmented tumors is sometimes mistakenly assessed as neuritis or unilateral congestion of the optic nerve disk.

Diagnosis of choroidal melanoma

It is extremely difficult to recognize choroidal melanoma in opaque media. In such cases, additional research methods (ultrasound scanning, computed tomography) help to clarify the diagnosis. Before deciding on the nature of treatment, the oncologist should conduct a thorough examination of the patient with uveal melanoma in order to exclude metastases. It should be remembered that during the initial visit to the ophthalmologist, metastases are found in 2-6.5% of patients with large tumors and in 0.8% with small melanomas.

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Treatment of choroidal melanoma

For over 400 years, the only treatment for choroidal melanoma was enucleation of the eyeball. Since the 1970s, organ-preserving treatment methods have been used in clinical practice, the purpose of which is to preserve the eye and visual functions, provided that the tumor is locally destroyed. Such methods include laser coagulation, hyperthermia, cryodestruction, radiation therapy (brachytherapy and irradiation of the tumor with a narrow medical proton beam). In case of preequatorially located tumors, their local removal (sclerouveectomy) is possible. Naturally, organ-preserving treatment is indicated only for small tumors.

Choroidal melanoma metastasizes hematogenously, most often to the liver (up to 85%), the second most common site of metastasis is the lungs. The use of chemo- and immunotherapy for uveal melanoma metastases is still limited due to the lack of a positive effect. The prognosis for vision after brachytherapy is determined by the size and location of the tumor. In general, good vision after brachytherapy can be preserved in almost 36% of patients with tumor localization outside the macular zone. The eye as a cosmetic organ is preserved in 83% of patients. After treatment, patients should be monitored almost for the rest of their lives. After radiation therapy and local tumor removal, the doctor should examine patients every 3 months for the first 2 years, then 2 times a year during the 3rd and 4th years, then once a year.