Melanoma of the choroid

Malignant tumors of the choroid are mainly represented by melanomas.

There are three mechanisms for the development of choroidal melanoma: the emergence as a primary tumor - de novo (most often) against the background of a previous choroidal nevus or existing oculodermal melanosis. Melanoma of the choroid begins to develop in the outer layers of the choroid, and, according to the latest data, is represented by two basic cellular types: spindle cell A and epithelioid. The spindle cell melanoma metastasizes in almost 15% of cases. The incidence of metastasis of epithelioid melanoma reaches 46.7%. Thus, the cellular characteristic of uveal melanoma is one of the determining factors of the prognosis for life. More than half of the melanomas are located behind the equator. Tumor, as a rule, grows in the form of a solitary knot. Usually, patients complain of visual impairment, photo and morphopsy.

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Symptoms of choroidal melanoma

In the initial stage, the melanoma of the choroid is represented by a small focus of brown or dark gray with a diameter of 6-7.5 mm, on the surface and around which are visible druses (keloid bodies) of the vitreous plate. Brushy cavities in the adjacent retina are formed as a result of dystrophic changes in pigment epithelium and the appearance of subretinal fluid. The orange pigment fields found on the surface of most melanomas are caused by the deposition of lipofuscin grains at the level of retinal pigment epithelium. As the tumor grows, its color may become more intense (sometimes even dark brown) or it remains yellowish-pink, pigmentless. Subretinal exudates appear when squeezing choroidal vessels or as a result of necrobiotic changes in a rapidly growing tumor. An increase in the thickness of melanoma causes dystrophic changes in the Bruch's membrane and retinal pigment epithelium, as a result of which the intactness of the vitreous plate is broken and the tumor sprouts under the retina - a so-called mushroom-shaped melanoma is formed. Such a tumor usually has a fairly wide base, a narrow isthmus in the Bruch's membrane and a globular head under the retina. When the Bruch membrane ruptures, hemorrhages can occur, which are the cause of an increase in retinal detachment or its sudden appearance. With juxtapapillary localization of melanoma, subretinal exudation in a number of cases causes stagnant phenomena in the optic nerve disk, which, with non-pigmented tumors, is sometimes mistakenly regarded as a neuritis or unilateral stagnant optic disc.

Diagnosis of choroidal melanoma

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

[5], [6], [7]

Treatment of choroidal melanoma

For more than 400 years, the only treatment for choroidal melanoma has been the enucleation of the eyeball. Since the 70s of the XX century in clinical practice began to use organ-preserving methods of treatment, whose goal is to preserve the eye and visual functions under the condition of local destruction of the tumor. Such methods include laser coagulation, hyperthermia, cryodestruction, radiotherapy (brachytherapy and tumor irradiation with a narrow medical proton beam). With preequatorially located tumors, their local removal (sclerouveoctomy) is possible. Naturally, organ-preserving treatment is indicated only for small tumors.

Choroidal melanoma metastasizes by hematogenous way, most often to the liver (up to 85%), second place in the frequency of metastases is occupied by the lungs. The use of chemotherapy and immunotherapy for metastases of uveal melanoma is limited so far due to the lack of a positive effect. The prognosis for vision after brachytherapy is determined by the size and localization of the tumor. In general, good vision after brachytherapy can be maintained 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 for almost the rest of their lives. After radiotherapy and local removal of the tumor, the doctor should examine patients every 3 months in the first 2 years, then 2 times a year for the 3rd and 4th year, then once a year.