Blood in the eye is supplied by blood vessels that branch from the retinal artery. This artery is located at the back of the eye, between the retina and sclera. The layer that contains blood vessels responsible for blood supply in the eye is known as the choroid. Together with the iris and ciliary body, they make up the uvea.
The choroid contains melanocytes, the same cells that give hair, skin and eyes their color. Presence of melanocytes makes it possible for melanoma to develop inside the eye, specifically on the choroid. When this happens, it is referred to as choroidal melanoma. It is responsible for most eye cancer related cases. Regardless, the disease is rare.
What is choroidal melanoma (CM)?
Melanoma is abnormal growth of melanocytes. It results from gene mutation thought to be caused by UV poisoning. To understand the basis of what CM is, learn more on what is malignant melanoma. Basically, it can be described as a mass of abnormally growing melanocytes with the ability to spread and invade other body organs.
In situ large choroidal melanomas end up displacing the retina. This causes vision interference and sometimes complete loss. It is estimated that 50% of all CMs will metastasize or spread to other body regions. Due to rich blood supply in the choroid, malignant cells spread through the blood system rather than lymphatic system. This makes the liver very prone to choroidal melanomas.
Other than the liver, metastasis can also result in melanoma on lip, brain, lungs and bones. This is why doctors insist on having suspicious tumors checked.
How fast does melanoma spread? It depends on the type of melanoma in question. For example, nodular melanoma is very invasive. It takes only a few months or weeks to reach its advanced stages. Acral lentiginous melanoma, or the one that affects hands and feet, can take years to start spreading. The other two types that mostly occur in sun-exposed areas first spread widely across the skin before becoming invasive.
Choroidal melanoma symptoms
Most CMs develop without showing any symptoms until much later. In fact, early ones are caught by opticians during eye checkups. Choroidal melanoma symptoms that may occur include:
- poor peripheral vision
- Seeing shadows or flashes
- Blurred vision
- Pain in the eye
Blurred vision occurs when the tumor pushes the iris. This makes it hard for the iris to control closing and opening of the pupil. As a result, the patient sees blurry objects. If the tumor is left without treatment, it can push the retina or leak fluid beneath it. As a result, the retina may detach. This is why some patients develop the tendency to see shadows or light flashes. Loss of vision occurs when CM grows into the fovea. This is the part of retina that produces very clear images.
Note that not always will these symptoms indicate choroidal melanoma. It is very common to develop vision problems. Regardless, see your doctor if the symptoms are to persist. Additionally, you may notice signs of tumors elsewhere in the body. It is not uncommon for cases such as melanoma on penis to result from other melanomas sometimes yet to be diagnosed.
Choroidal melanoma causes
Exact choroidal melanoma causes are yet to be uncovered. There are reasons to believe that changes in the DNA have something to do with the disease’s occurrence. Risk factors include:
- UV radiation – melanomas are known to occur more often when UV radiation exposure is involved. While the sun is the largest source of UVs, artificial devices such as tanning beds also produce the rays. Melanoma on hand is also linked to UV poisoning.
- Eye pigment – compared to people with brown eye pigment, those with blue pigment tend to be more prone to CM.
- Hereditary factors – there is a condition referred to as dysplastic moles nevi syndrome. People with the condition develop up to 100 moles randomly on the skin. It has been observed that such people are more likely to develop melanoma. More cases are also reported in light skinned people. Note that a risk factor doesn’t guarantee that a disease will develop.
Cancers have a tendency of sometimes coming back even after first successful treatment. For example, nodular melanoma symptoms can occur several years after choroidal melanoma. Ensure to collect details on your medical history before an appointment.
Choroidal melanoma prognosis and staging
Choroidal melanoma prognosis is best when tumors are confined to the eye. Likelihood that patents will survive the next five years or more is 80% in this case.
Once the cancer has spread to blood system, liver and other distant organs, prognosis is very poor. 5-year-survival rate is below 20%.
Staging is done on basis of tests results. The most recent staging system uses the so called TNM system.
- T stands for tumor. It describes how deeply rooted the tumor is. The information will also tell if the tumor has penetrated the dermis.
- N stands for nodes. It tells whether malignant cells have migrated to local lymph nodes (behind ear and on neck). It also contains information on whether other eye sections have been invaded.
- M stands for metastasis. This is the process by which malignant tumors migrate and invade distant organs. Information in this section tells whether tumors have metastasized. In most cases, the liver will be the first organ to be invaded.
Traditional staging puts tumors in 4 main stages. Stage I tumors are still in the original site and usually small. Stage II tumors have grown large enough to penetrate the dermis. Stage III tumors have entered the lymphatic system, while stage IV have migrated to distant organs.
Choroidal melanoma diagnosis
Several tests may be conducted to check for choroidal melanomas. They include:
During this test, a doctor will use an ophthalmoscope to check for signs of malignancy. This is achieved by shining a bright light to the eye or using a magnifying lens for better view of inside eye. Before the examination, eye drops are used to dilate the eye.
During this test, a dye will be injected into a vein in the arm. A camera will then be used to take rapidly sequenced photos of the inside eye as the dye circulates.
Sound waves return to source once they hit a mass. The size of the mass they have bounced off determines their return frequency. This is captured in the form of images on a computer screen.
A small sample of the choroid tissue is extracted and checked for malignant cells under a microscope. Excisional biopsy is more effective. Melanoma biopsy may also involve injecting dye in a site where a tumor has been removed and tracing its circulation in local lymph nodes. This test is used to check for metastatic cells in the lymphatic system.
Your doctor may also take a blood test to check the level of liver functions. As hinted earlier, most choroidal melanomas spread to the liver at first. Reduced liver functions may therefore indicate presence of a melanoma. Apart from blood test, imaging tests with MRIs and CT scans may also be taken.
Choroidal melanoma treatment
The best choroidal melanoma treatment option depends on factors such as thickness of the tumor, age and general health status. In some cases, doctors choose not to remove the melanomas but to closely monitor them. Treatment options include:
Excisional surgery is most common of all small melanoma treatment options. Before the surgery, imaging tests will be taken to show the size of the tumor. An excisional margin will then be determined.
Surgery can also be done to remove the entire eye. This is only necessary for large melanomas or when tumors are causing a lot of pain. Once the eye has been removed, a movable implant will be fixed. This will be replaced with an artificial eye after recovery.
Radiotherapy is mostly used to reduce pain caused by spreading tumors as well as mitigate tumor growth. It may also be used in combination with surgery to destroy any melanoma tissues which escaped surgery.
Chemotherapy is use of drugs to kill cells that rapidly divide. It is common for cancer cells to divide in large numbers under a very short timeline. Chemotherapy ends up destroying even healthy fast dividing cells such as hair cells.
Immunotherapy was recently introduced as a cancer treatment method. Drugs are administered to boost the immune system’s ability to identify and destroy cancer cells.
This is also a recent introduction to the world of cancer treatment. It specifically targets cancer cells. The treatment is a form of improvised chemotherapy.
Cryotherapy is rarely used for choroidal melanoma treatment nowadays. It uses a very cold substance to destroy tumors. After the treatment, chemotherapy eye drops are often administered. Another alternative involves destroying tumors with lasers. In most cases, infrared lasers are used.
Prevention and outlook
Since it not clear what causes choroidal melanoma, the best prevention approach is to go for routine eye checkups. The location of the choroid makes it hard to see tumors during self-examination. After treatment, make sure to go for follow-up appointments. See your doctor immediately you notice metastatic melanoma symptoms.
Choroidal melanoma is the most common of all eye cancers. It is not fatal unless it spreads to the liver. Without treatment, resulting tumors can lead to vision loss.
Always go for top centers which provide eye cancer treatment. You can in this way choose from a wide variety of treatment options, especially without having to go through complete eye removal.
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