Malignant Neoplasm of Choroid

Choroidal melanoma is a rare but serious cancer that develops in the eye’s middle layer, representing the most common primary eye cancer in adults, though it affects only a small number of people each year.

Table of contents

• What is choroidal melanoma
• Who gets choroidal melanoma
• Location in the eye
• Signs and symptoms
• How it is diagnosed
• Treatment options
• Outlook and prognosis

What is choroidal melanoma

Choroidal melanoma is a type of cancer that develops in the choroid, which is the layer of blood vessels and tissue located between the retina and the outer white part of the eye. This layer supplies oxygen and nutrients to the retina, the light-sensing tissue at the back of the eye^[1].

The tumor originates from melanocytes, which are cells that produce melanin, the pigment that gives color to our skin and eyes. When these cells become cancerous in the choroid, they form what is called choroidal melanoma^[1].

Although choroidal melanoma is rare, it is the most common primary cancer that starts inside the adult eye. It accounts for about 90% of all uveal melanomas, which are cancers affecting the uveal tract of the eye. The uveal tract includes the iris (the colored part of the eye), the ciliary body (tissue around the lens), and the choroid^[1][8].

• Choroid
• Eye
• Uveal tract

Who gets choroidal melanoma

Choroidal melanoma is quite uncommon. The incidence is approximately 5 to 7.5 cases per million people each year in populations of European descent^[1]. This makes it a rare condition, though it remains the most frequent primary eye cancer in adults.

The disease affects some groups more than others. People with light-colored skin, blue or green eyes, and those who have fair skin that burns easily are at higher risk^[1][8]. The condition is slightly more common in males than females^[1].

Age is an important factor. While choroidal melanoma can occur at any age, most cases are diagnosed in people around 55 years old. Some studies indicate that the peak age range for diagnosis is between 70 and 79 years, with a median age of about 63 years^[1].

Location in the eye

To understand choroidal melanoma, it helps to know how the eye is structured. The eye wall has three main layers. The outer layer includes the white part of the eye called the sclera and the clear window at the front called the cornea. The inner layer contains the retina, which senses light and sends images to the brain through the optic nerve^[8].

Between these two layers is the middle layer, called the uvea or uveal tract. This middle layer has three parts: the iris (the colored part you see when you look at someone’s eye), the ciliary body (a ring of tissue behind the iris that helps the lens change shape), and the choroid (a layer filled with blood vessels that nourishes the retina)^[8].

The choroid is located just beneath the retina and lines the back inside portion of the eye. Because it is rich in blood vessels, when cancer develops here, it has the potential to spread to other parts of the body through the bloodstream^[1].

Signs and symptoms

Many people with choroidal melanoma do not notice any symptoms, especially in the early stages. The tumor can remain undetected for a long time and may be discovered during a routine eye examination^[3][1].

When symptoms do appear, they may include blurred vision or other changes in how well you can see. Some people experience floaters, which look like dark spots or specks of dust drifting in your vision. Others see flashes of light, called photopsia^[1][3].

Progressive loss of vision in parts of the visual field can occur, meaning that you may not be able to see as well when looking to the side. This is known as loss of peripheral vision. Some people notice that straight lines appear wavy, a symptom called metamorphopsia^[3].

In more advanced cases, severe eye pain can develop, though this is less common. Pain usually occurs when the tumor causes complications such as increased pressure inside the eye or inflammation^[3].

How it is diagnosed

Choroidal melanoma is most often diagnosed during a thorough eye examination. Your eye doctor will look inside your eye after dilating your pupils with special drops. This allows them to see the back of the eye, including the retina and choroid, where the tumor may be located^[3][13].

During the examination, small choroidal melanomas typically appear as a dome-shaped, well-defined mass under the layer of cells that support the retina. As tumors grow larger, they may take on irregular shapes, sometimes resembling a mushroom. Some tumors are darkly pigmented, while others are lighter in color or partially pigmented^[3].

Several diagnostic tests help confirm the diagnosis and determine the size and characteristics of the tumor. Ultrasonography, which uses sound waves to create images of the inside of the eye, is one of the most valued tests. Both A-scan and B-scan ultrasound can measure the thickness and dimensions of the tumor^[1][3].

Other imaging techniques include special photographs of the inside of the eye, called fundus photography, and fluorescein angiography, which examines blood flow in the eye. Optical coherence tomography (OCT) is a test that produces detailed cross-sectional images of the retina and can detect fluid beneath the retina caused by the tumor^[13].

In most cases, a biopsy is not necessary to diagnose choroidal melanoma. Eye cancer specialists are able to correctly identify these tumors through clinical examination and imaging in more than 99% of cases. However, a biopsy may be performed in certain situations, such as when the tumor has an unusual appearance or when genetic testing of the tumor is desired^[2].

Treatment options

Treatment for choroidal melanoma depends on the size and location of the tumor, as well as your overall health and vision. The main goals are to prevent the cancer from spreading to other parts of the body, preserve as much vision as possible, and save the eye^[11].

For many patients, radiation therapy is the primary treatment. This can be delivered in different ways. Episcleral brachytherapy, also called plaque radiotherapy, involves temporarily placing a small radioactive device on the outside wall of the eye next to the tumor. The radiation kills the cancer cells over several days, after which the device is removed^[6][9].

Another form of radiation is proton beam therapy, which uses a specialized beam of protons to target the tumor precisely. This type of treatment is available at certain specialized centers^[9].

In some cases, surgery may be recommended. For very large tumors, tumors causing severe complications, or when there is no remaining vision in the affected eye, enucleation (surgical removal of the eye) may be necessary. After this procedure, patients can be fitted with an artificial eye that provides good cosmetic appearance^[11].

Smaller tumors or those in certain locations may be treated with laser therapy. Some patients may benefit from a combination of treatments^[6].

After treatment, regular follow-up is essential. Your doctor will monitor the treated eye to check for any signs that the tumor is growing again. You will also need regular check-ups to watch for signs that the cancer may have spread to other parts of the body, particularly the liver, which is the most common site for spread^[3][1].

Outlook and prognosis

Several factors affect the outlook for people with choroidal melanoma. The size and thickness of the tumor are important. Generally, smaller and thinner tumors have a better prognosis than larger, thicker ones. Tumors with well-defined edges also tend to have better outcomes than those with unclear boundaries^[23].

The location of the tumor within the eye matters as well. Melanomas that start in the iris typically have a better prognosis than those that begin in the choroid or ciliary body^[23].

The type of cells that make up the tumor also plays a role. Tumors composed primarily of spindle-shaped cells tend to have more favorable outcomes than those made up of round epithelioid cells or a mixture of cell types^[23].

Patient age is another factor. The stage at which the cancer is detected matters greatly—early detection generally leads to better outcomes. Whether the cancer has spread beyond the eye is the most critical factor affecting survival. Choroidal melanoma can spread to other organs, most commonly the liver^[3].

Research indicates that approximately 50% of patients with choroidal melanoma may eventually develop spread of the disease to other parts of the body, even with appropriate primary treatment and careful monitoring^[1]. This is why long-term follow-up care is so important.

Despite these concerns, many patients with choroidal melanoma, especially those diagnosed early with small tumors, can be successfully treated with eye-preserving therapies and maintain good quality of life. Treatment for small to medium-sized tumors often allows patients to keep useful vision in the affected eye^[9].