Ciliary body melanoma is an uncommon type of cancer that develops within the eye. This malignancy originates in the ciliary body, a small, circular structure located behind the iris, the colored part of the eye.
What is Ciliary Body Melanoma?
Ciliary body melanoma is a malignant tumor arising from pigment-producing cells (melanocytes) within the ciliary body. This structure is a component of the uvea, which is the eye’s middle layer, also encompassing the iris and the choroid. The ciliary body is a ring-shaped tissue positioned behind the iris, connecting it to the choroid.
The ciliary body performs two main functions: it generates aqueous humor, a clear fluid that nourishes the eye and maintains its internal pressure, and it contains muscles that adjust the lens for focusing. Melanomas in this region are considered a subtype of uveal melanoma, the most common primary eye cancer in adults. However, ciliary body melanoma is less frequent, accounting for approximately 7% to 12% of all uveal melanomas, making it rarer than those found in the choroid. These tumors can develop spontaneously or from a pre-existing melanocytic nevus, and their cellular composition can influence their behavior.
Identifying Potential Symptoms
Symptoms of ciliary body melanoma can be subtle or absent in the early stages, often due to the tumor’s hidden location behind the iris. As the tumor grows, individuals may notice changes in their vision. This can include blurry vision if the tumor affects the lens or causes astigmatism.
Flashes of light or an increase in the number of floaters, which are small specks or strands that drift across the field of vision, can also be present. Less commonly, a visible dark spot may appear on the iris, or the pupil’s shape might change if the tumor extends forward. A dilated, tortuous episcleral blood vessel visible over the tumor can be an early external sign. In some cases, pressure on the lens by the growing tumor can lead to lens displacement, potentially causing secondary glaucoma and associated pain.
How Ciliary Body Melanoma is Diagnosed
Diagnosing ciliary body melanoma involves a comprehensive eye examination by an ophthalmologist. During this examination, the doctor may use a slit-lamp biomicroscope with a triple mirror contact lens to observe the internal structures of the eye. This allows for visualization of the ciliary body and any abnormal masses.
Ocular ultrasound is a standard diagnostic tool used to measure the tumor’s size, shape, and internal characteristics. Optical coherence tomography (OCT) can provide high-resolution cross-sectional images of the eye’s layers, helping to assess the tumor’s extent and any associated fluid. Angiography, which involves injecting a dye to visualize blood vessels, can highlight the tumor’s vascular supply. Early detection through these methods guides treatment decisions and improves outcomes.
Treatment Options
Treatment for ciliary body melanoma is tailored to the tumor’s size, location, and potential impact on vision. One common approach is brachytherapy, which involves surgically attaching a small radioactive plaque directly to the eye wall over the tumor. This plaque delivers localized radiation to destroy the cancer cells while minimizing damage to surrounding healthy tissue. The plaque is left in place for several days before being removed.
Another external radiation therapy is proton beam therapy, which delivers precise beams of protons to the tumor. This concentrates the radiation dose to the melanoma while sparing adjacent structures. For smaller tumors, transpupillary thermotherapy (TTT) might be used, applying infrared laser energy to heat and destroy the cancerous cells. This procedure is less invasive but is limited by tumor size and location.
Surgical removal of the eye, known as enucleation, is considered for larger tumors, those that have caused significant vision loss, or when there is evidence of spread beyond the eye. In some cases, a local resection, which is the surgical removal of only the tumor and a small amount of surrounding healthy tissue, may be performed. The choice among these treatments depends on an assessment of the individual case to achieve the optimal outcome.
Prognosis and Follow-up Care
The long-term outlook for individuals with ciliary body melanoma is influenced by several factors, including the tumor’s size at diagnosis, its location within the ciliary body, and whether it has shown signs of spreading. Smaller tumors detected early tend to have a more favorable prognosis. The cellular characteristics of the tumor can also play a role in predicting its behavior.
After treatment, regular follow-up appointments monitor for any signs of recurrence within the eye or metastasis (the spread of cancer to other parts of the body). These visits include comprehensive eye examinations, various imaging tests of the eye, and systemic imaging, particularly of the liver, as it is a common site for melanoma to spread. Ongoing medical care is part of managing this condition over the long term.