Background

Choroidal melanoma, also known as ocular melanoma, is a rare and potentially life-threatening form of cancer that originates in the pigmented cells of the choroid, the middle layer of the eye. The choroid plays a crucial role in providing blood to the retina, while melanocytes, which are responsible for producing melanin pigment, naturally reside within this layer.

Choroidal melanoma is a specific type of uveal melanoma. Uveal melanomas are categorized into two distinct groups: (1) anterior uveal melanomas, where the tumor originates in the iris, and (2) posterior uveal melanomas, The tumor can originate in each of two the ciliary body or the choroid. In some cases, intraocular melanomas can affect multiple structures within the uvea simultaneously.

The early stages of choroidal melanoma often do not cause noticeable symptoms, which can make early detection challenging. As the tumor grows, however, it may lead to various visual disturbances, such as blurred or decreased vision, the appearance of flashes or floaters in the eye.

Epidemiology

United States statistics

When considering statistics in the United States, it has been found that the incidence of primary choroidal melanoma is approximately six cases by one million people. The elevated incidence of uveal melanoma in the southern latitudes of the country could be attributed to the enhanced levels of sunlight exposure.

International statistics

countries with a significant population of individuals with northern European ancestry have a much increased incidence of choroidal melanoma compared to other regions worldwide. For instance, in other Scandinavian countries and in Denmark. The estimated occurrence rate stands at approximately 7.5 cases per million individuals annually.

Age-related differences in incidence

The inflated occurrence of choroidal melanoma is typically observed at the age of 55 years. although this tumor is quite rare, reports suggest a peak occurrence at a slightly younger age. It is important to note that choroidal melanoma is extremely uncommon in children.

Sex-related differences in incidence

choroidal melanoma is slightly more prevalent in men across all age groups, except for the 20-39 age range, where there is a slight inclination towards women.

Anatomy

Pathophysiology

• Primary choroidal melanoma originates from melanocytes found in the choroid. The majority of choroidal melanomas are thought to emerge from pre-existing melanocytic nevi, although some cases of choroidal melanoma can develop de novo.
• Choroidal and other uveal melanomas can be categorized into three distinct cell types: spindle A, spindle B, and epithelioid. Out of these, the epithelioid cell type is generally linked to a more aggressive behavior and a less favorable prognosis in terms of long-term patient survival.
• Once the melanocytes transform into cancerous cells, it start to divide and form a tumor in the choroid layer. This tumor grows and slowly invades surrounding tissues.
• The liver, lungs, and bones are frequently identified as the primary locations for metastasis.
• As the tumor grows, it can compress nearby blood vessels, including the central retinal artery and vein, leading to decreased blood flow and impaired oxygenation to the retina. This can result in vision changes and other ocular symptoms.

Etiology

• Sun Exposure: Prolonged and intense exposure to (UV) rays directly from the sun or artificial sources, such as tanning beds, has been suggested as a potential risk factor for choroidal melanoma. However, unlike cutaneous melanoma, the association between sun exposure and choroidal melanoma is not as well-established.
• Family History: Having a family history of choroidal melanoma may increase an individual’s risk of developing the disease. However, the majority of cases occur sporadically, without a known family history.
• Age and Race: there is a slightly higher incidence of choroidal melanoma in individuals with light-colored eyes and fair skin. However, it can affect people of all races.

Genetics

Prognostic Factors

• Tumor size: The size of the choroidal melanoma is a crucial prognostic factor. Larger tumors tend to have more chances of metastasis and are associated with a poorer prognosis.
• Tumor location: The location of the choroidal melanoma within the eye can impact the prognosis. Tumors that are closer to the optic nerve or involve the ciliary body may have a higher risk of spreading and are often associated with a poorer prognosis.
• Tumor cell type: The cell type of the choroidal melanoma can affect its behaviour and prognosis. The most common cell types include spindle cell melanoma, mixed cell melanoma, and epithelioid cell melanoma. Epithelioid cell melanomas tend to have a higher risk of metastasis and a worse prognosis compared to the other types.
• Patient age: The prognosis can be affected by the patient’s age during the time of diagnosis. Younger patients generally have a better prognosis compared to older patients.

Clinical History

CLINICAL HISTORY

Age Group: Choroidal melanoma has the potential to manifest in people of all age groups; however, it tends to be more frequently identified among adult patients, typically between the ages of 40 and 60. However, it can also affect younger individuals and, although rare, even children.

Physical Examination

PHYSICAL EXAMINATION

• Patients who have choroidal melanoma may experience painless vision impairment or, in some cases, inflammation and discomfort due to a complex tumor. Nevertheless, numerous patients remain asymptomatic, and melanomas are detected during regular eye exams.
• Typically, small choroidal melanomas manifest as a rounded, dome-shaped mass situated beneath the retinal pigment epithelium. As they continue to develop, their shape may become more irregular, such as bilobular, multilobular, or mushroom-like configurations.

Age group

Associated comorbidity

Associated Comorbidities or Activities: There are no specific comorbidities or activities directly associated with the development of choroidal melanoma.

Nevertheless, certain factors posing a potential risk have been acknowledged, comprising fair skin, light-colored eyes (blue or green), and exposure to ultraviolet (UV) radiation.

Associated activity

Acuity of presentation

Acuity of Presentation:

Blurred or distorted vision: The tumor can cause visual disturbances, such as blurred vision or a change in the shape or size of objects.

Visual field defects: Choroidal melanoma can lead to peripheral vision loss or visual field defects.

Eye pain or redness: In some cases, patients may experience eye pain, discomfort, or redness.

Differential Diagnoses

DIFFERENTIAL DIAGNOSIS

Conjunctival Melanoma

Glaucoma, Hyphema

Neovascular Glaucoma

Intraocular Foreign Body

Iris Melanoma

Choroidal Detachment

Hyphema

Cavernous Hemangioma

Chronic Angle Closure Glaucoma

Vitreous Hemorrhage

Ciliary Body Melanoma

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Staging

Treatment Paradigm

TREATMENT PARADIGM

Modification of Environment:

• Protect your eyes from UV radiation: Increased exposure to ultraviolet (UV) rays from the sun can increase the risk of eye damage and certain eye diseases. It is recommended to wear sunglasses that provide full UV protection whenever outdoors. Additionally, wearing a wide-brimmed hat can offer extra shielding for your eyes against the sun’s rays.
• Practice good eye hygiene: Proper eye hygiene can help prevent eye infections and reduce the risk of complications. Avoid touching your eyes with dirty hands, clean your contact lenses thoroughly, and follow the recommended hygiene practices for eye care.

Administration of Pharmaceutical Agents with Drugs:

• Radiation Therapy: Choroidal melanoma is often treated with radiation therapy, which can help to destroy or control the growth of cancer cells. Different forms of radiation therapy may be used, including plaque brachytherapy and proton beam therapy. Plaque brachytherapy involves the surgical placement of a small radioactive plaque on the sclera (the white part of the eye) near the tumor. The plaque remains in place for a specified period, delivering a targeted dose of radiation to the tumor.
• Targeted Therapy: In recent years, targeted therapies have emerged as a potential treatment option for certain genetic mutations associated with choroidal melanoma. The most common genetic alteration in these tumors is a mutation in the GNAQ or GNA11 genes. Drugs like selumetinib and other MEK inhibitors have shown promise in inhibiting the abnormal signaling pathways caused by these mutations.
• Immunotherapy: Immunotherapy refers to the administration of medications that enhance the immune system’s ability to identify and combat cancerous cells. Immune checkpoint inhibitors, like pembrolizumab and nivolumab, have demonstrated promising results in treating advanced melanoma.

Intervention with a Procedure:

• Pre-treatment evaluation: This may include imaging studies, such as ultrasound or MRI, and measurements in order to exactly identify the location and size of the tumor.
• Plaque placement: Typically, the plaque is securely attached to the sclera, the outer white layer of the eye, using sutures. Meticulous planning is involved in determining the precise placement of the plaque to ensure the tumor receives the most effective radiation dosage while minimizing any harm to the adjacent healthy tissue.
• Radiation delivery: After the plaque has been placed, it is left undisturbed for a predetermined duration for some days or few weeks.The radioactive material within the plaque emits radiation that penetrates the eye and targets the tumor cells. The exact duration of radiation exposure depends on the specific treatment plan determined by your medical team.
• Post-treatment care: After the desired radiation dose is delivered, the plaque is removed, typically under local anesthesia. It may be necessary for patient to remain at the hospital temporarily for observation and to receive the necessary post-operative care.

Phase of Management:

• Diagnosis: Choroidal melanoma is usually diagnosed through a comprehensive eye examination, which may include a dilated eye exam, ophthalmoscopy, imaging tests (such as ultrasound, optical coherence tomography, or fluorescein angiography), and a biopsy if necessary. The diagnosis involves confirming the presence of a malignant tumor in the choroid, the pigmented layer at the back of the eye.
• Staging: Once diagnosed, the tumor is staged to determine its size, location, extent, and potential for spreading (metastasis). Staging helps in determining the appropriate treatment approach and prognosis. The most commonly used staging system for choroidal melanoma is the (American Joint Committee on Cancer ) TNM system, The evaluation takes into account the dimensions of the tumor, its invasion into neighboring tissues, and the existence of metastatic spread.
• Treatment: The selected treatment option is implemented according to the treatment plan. Radiation therapy is a common approach for preserving the eye and vision. Brachytherapy involves placing a small radioactive plaque near the tumor, delivering targeted radiation to kill cancer cells. Proton beam therapy is another radiation technique that uses charged particles to precisely target the tumor while minimizing damage to surrounding healthy tissue.

by Stage

by Modality

Chemotherapy

Radiation Therapy

Surgical Interventions

Hormone Therapy

Immunotherapy

Hyperthermia

Photodynamic Therapy

Stem Cell Transplant

Targeted Therapy

Palliative Care

Medication

Future Trends

Media Gallary

References

Singh P, Singh A. Choroidal melanoma. Oman J Ophthalmol:ncbi.nlm.nih