Intraocular lymphoma, also known as vitreoretinal lymphoma, is a rare form of non-Hodgkin lymphoma (NHL). Intraocular means “inside the eye” and lymphoma is a type of cancer. The tumors of intraocular lymphoma can result in visual changes and sometimes cognitive or behavioral changes. As a “masquerade syndrome,” intraocular lymphoma can mimic characteristics of common eye conditions such as chronic uveitis (eye inflammation). The similar symptoms have made intraocular lymphoma one of the most difficult types of eye cancer to diagnose and treat.
Intraocular lymphoma is very rare, making up less than 1 percent of total NHL cases. In 2020, about 3,400 adults in the U.S. were diagnosed with ocular cancers, including lymphoma, melanoma, and others. However, there is no central database for intraocular lymphoma, so it is difficult to estimate its exact prevalence.
This article discusses an overview of intraocular lymphoma, including causes, risk factors, symptoms, diagnosis process and procedures, and current treatments.
Intraocular lymphoma is a type of cancer that arises from an abnormal immune response of lymphoid cells (a type of white blood cells) located inside of the eyeball. Most intraocular lymphomas affect the:
Between 80 percent to 90 percent of people will develop intraocular lymphoma in both eyes.
Intraocular lymphoma is a high-grade (fast-growing) cancer. It is also a subtype of primary central nervous system lymphoma (PCNSL). PCNSL is a rare form of diffuse large B-cell lymphoma in the majority of cases, although sometimes T-cell lymphomas can occur. About 90 percent of people who have intraocular lymphoma will develop central nervous system (CNS) lymphoma within approximately two years. Intraocular lymphoma can develop before, after, or at the same time as CNS lymphoma. The CNS includes the brain, spinal cord, and optic nerves.
There are two main types of intraocular lymphoma: primary and secondary. Primary intraocular lymphoma (PIOL) arises from the central nervous system and is more common. PIOL affects the retina, vitreous fluid, and optic nerve head. Secondary intraocular lymphoma (SIOL) is lymphoma that has spread to the eye from another part of the body. SIOL commonly affects the uvea of the eye (the middle layer of the eye), specifically the layer called the choroid.
A common sign of intraocular lymphoma is uveitis, or eye inflammation, which occurs in 75 percent of cases. Symptoms of intraocular lymphoma may respond to uveitis treatment, which makes it a challenge for clinicians to properly diagnose intraocular lymphoma. Additionally, some people may have vitreitis, an inflammation of the vitreous of the eye that requires an examination to diagnose.
The most common symptoms include:
If intraocular lymphoma occurs with CNS involvement, a person may also experience:
The cause of intraocular lymphoma is unknown. However, experts have identified some risk factors. A risk factor is something that can make a person more likely to develop cancer. Having one or several risk factors doesn’t guarantee a person will develop cancer, however, and a person can also develop cancer without having any risk factors.
Intraocular lymphoma is difficult to diagnose because it looks or acts like other eye conditions. A delayed diagnosis can cause the intraocular lymphoma to spread to the brain and spinal cord and decrease a person’s survival time. However, recent advancements in the diagnostic tools to detect intraocular lymphoma early offer a promising outlook for many people.
Diagnosing intraocular lymphoma may involve biopsies, imaging tests, and genetic testing.
A vitrectomy, or taking a sample of vitreous tissue, is one of the primary diagnostic tests to diagnose intraocular lymphoma. Intraocular lymphoma cells are typically found within the vitreous of the eye and appear larger compared to normal lymphocytes.
There are a few ocular imaging tests that may be performed to diagnose lymphoma or rule out other inflammatory ocular conditions.
Researchers from the University of California, San Francisco and the Proctor Foundation have recently created a new diagnostic tool for intraocular lymphoma, called metagenomic deep sequencing (MDS). MDS takes a sample of intraocular fluid and detects intraocular lymphoma biomarkers (such as genetic mutations, bacteria, and viruses). This method is a major advance that may replace the need for biopsies for intraocular lymphoma in the future.
Intraocular lymphoma is typically treated with chemotherapy or radiation therapy. It is important for your oncologist, ophthalmologist, and pathologist to work together in the treatment plan of your intraocular lymphoma.
Chemotherapy can be administered in various ways: through a vein, through the spinal fluid, or directly in the eye. Delivering the chemotherapy to the eye or spinal fluid allows the ophthalmologist to treat the tumor directly and decrease potential side effects. The most commonly prescribed drugs are methotrexate and Rituxan (rituximab).
Radiation therapy essentially uses high amounts of energy to kill the cancer cells or shrink tumors. Low-dose external beam therapy is a more preferred treatment in people with bilateral intraocular lymphoma. It may also be effective in preventing cancer from spreading to the brain or spinal cord. This treatment can affect vision.
Intraocular lymphoma is often diagnosed late and after cancer has spread to the brain. As a result, the prognosis (outlook) is not very good, with an overall survival rate of about three years. Factors that determine the outlook of disease vary from person to person, however. People with intraocular lymphoma should discuss their disease prognosis with their doctor.
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