Primary central nervous system lymphoma (PCNSL) is a type of cancer that develops in the brain or spinal cord. It starts in the lymphatic system, within immune cells called lymphocytes.

People with compromised immune systems, especially those living with HIV, are at higher risk of developing PCNSL.

PCNSL is a rare form of non-Hodgkin lymphoma involving lymphatic tissue in the brain or spinal cord. Cancer forms in immune cells called lymphocytes, which reside in the lymph tissue and can spread to other parts of the body.

PCNSL can occur in several different locations of the central nervous system (CNS). When it develops in the spinal fluid that surrounds the brain and spinal cord, doctors call it leptomeningeal lymphoma. It can also occur in the eyes, because they are close to the brain. In this case, healthcare professionals call it ocular lymphoma.

PCNSL is a type of extranodal, high-grade non-Hodgkin B-cell lymphoma. About 90% of cases are diffuse large B-cell lymphoma, with the remaining cases consisting of poorly characterized low-grade lymphomas, Burkitt lymphomas, and T cell lymphomas.

This article explores the symptoms, causes, risk factors, staging and diagnosis, treatment, and outlook for PCNSL.

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PCNSL is a type of non-Hodgkin lymphoma that develops when immune cells called lymphocytes become malignant in areas of the CNS. These areas may include the brain, spinal cord, and eyes.

People with compromised immune systems and older adults have an increased risk of developing PCNSL.

The disease is a defining illness of living with AIDS, meaning doctors generally consider individuals who are HIV positive and develop PCNSL as having AIDS.

Symptoms of PCNSL can mimic other disease conditions. Therefore, it is a good idea to check with a doctor if a person experiences:

  • nausea and vomiting
  • seizures
  • headaches
  • limb weakness
  • confusion
  • double vision
  • hearing loss

If ocular lymphoma develops, a person may notice blurred vision, and if the cancer reaches the spinal cord or spinal cord fluid, there may be incontinence or back pain.

Health experts do not understand fully how malignant lymphocytes pass into the brain. However, there are two main theories. The first suggests the CNS might draw lymphocytes to the area, where they then replicate, causing a malignant tumor. The other states the CNS might attract already-malignant lymphocytes into the area via specific chemical reactions in the brain.

PCNSL generally spreads due to the overgrowth of cells from B lymphocytes, which are also called B cells. Occasionally, PCNSL can develop due to the uncontrolled growth of T cells, but the general understanding is that treatment targets B cell lymphomas.

The immune system is usually involved in the destruction of abnormal or malignant cells. However, PCNSL has the ability to overcome or avoid the immune system’s normal suppression response.

Experts believe that the vascular structure of the brain may also play a role in the growth of PCNSL tumors, which tend to develop near blood vessels.

The Epstein-Barr virus may also be a factor in the development of PCNSL among immunocompromised individuals.

The causes of PCNSL are unknown, but several factors may increase a person’s risk of developing it. These include having a compromised immune system due to:

  • HIV
  • other immune system disorders
  • chronic immunosuppression
  • organ transplantation

There is no standardized system for staging PCNSL, since it does not spread beyond the CNS or the eye. CT scans, PET scans, MRIs, bone marrow aspirations, and biopsies may all form part of the diagnosis process.

Additionally, PCNSL does often reoccur in the brain, spinal cord, or eye after treatment.

To diagnose PCNSL, a doctor will carry out a complete medical examination, including taking a person’s detailed health history. They may then order one or more tests, which could include:

  • a neurological exam
  • a slit-lamp eye exam to examine the inside and outside of the eye
  • a vitrectomy, a surgical procedure that removes some of the vitreous humor from the eyeball to check for cancer cells
  • chest X-rays and CT scans of the chest or abdomen
  • MRI scans of the brain or spinal cord
  • blood or urine tests
  • a lumbar puncture
  • a stereotactic biopsy, a three-dimensional scanning device that locates a tumor and guides tissue removal for examination

Doctors also usually test people for HIV due to a known link between HIV and PCNSL.

PCNSL only affects a small number of people each year. When looking for a treatment provider, it is important to find someone who is comfortable treating non-Hodgkin lymphoma.

There are a few standard treatments available for PCNSL unrelated to AIDS:

  • radiation therapy
  • chemotherapy
  • steroids
  • whole-brain radiation
  • high dose chemotherapy with stem cell transplant

For PCNSL related to AIDS, treatments include:

  • HIV medications
  • steroids with or without medications
  • chemotherapy with or without radiation

A 2017 study indicates that there have been major advancements in treating PCNSL. Up to half of those who receive a PCNSL diagnosis are now likely to see it go into remission. However, relapses may occur more than 10 years after the initial diagnosis.

Currently, doctors are working to optimize treatments to reduce the chances of remission and improve the number of treatment options.

Additionally, the increase in older adults having a PCNSL diagnosis means more trials focusing on this population are necessary.

PCNSL is a rare form of cancer that targets the brain, spinal cord, and sometimes the eyes. It is a particular concern for anyone who is immunocompromised or has a weakened immune system, such as from an organ transplant.

Treatments include many standard cancer therapies such as radiation, chemotherapy, and steroids. Research shows that quick, aggressive treatment may provide optimal outcomes.

PCNSL symptoms can mimic those of other conditions, so anyone experiencing them should consult a doctor as soon as possible for evaluation.