What Is Primary Central Nervous System Lymphoma?
A severe form of non-Hodgkin’s lymphoma (NHL) known as primary central nervous system lymphoma (PCNSL) occurs when cancerous cells grow in the brain or spinal cord's lymph tissue. It can appear in the leptomeninges (two membranes that cover the brain and spinal cord), the brain, the spinal cord, or the eye. Secondary CNS lymphoma is the term used to describe lymphomas that have moved to the central nervous system (CNS) after initially developing in another area of the body. Primary diffuse large B-cell lymphoma of the central nervous system is by far the most prevalent type of PCNSL.
What Is the Typical Incidence of Primary CNS Lymphoma?
PCNSL accounts for less than one percent of all non-Hodgkin lymphomas, five percent of all extranodal lymphomas, and between four and six percent of all brain malignancies. It is the third most frequent cancer that mainly affects the central nervous system, following diffuse astrocytoma (a brain or spinal cord tumor that begins in star-shaped cells called astrocytes) and glioblastoma (an aggressive brain tumor). This type of lymphoma is typically diagnosed at 65 years of age, and it primarily affects those over 50. Men and those assigned male at birth (AMAB) are significantly more likely to have it. Individuals who have HIV (human immunodeficiency virus), AIDS (acquired immunodeficiency syndrome), or other immunodeficiencies are at an increased risk of being diagnosed with CNS lymphoma.
How Does Primary CNS Lymphoma Arise?
Similar to other forms of lymphoma, CNS lymphoma arises from aberrant behavior of lymph tissue cells. They take over healthy cells and proliferate uncontrollably. B-cells, which are white blood cells or lymphocytes, are typically the cells that begin to proliferate abnormally when a person has CNS lymphoma.
What Are the Clinical Features of Primary Central Nervous System Lymphoma?
The symptoms of primary central nervous system lymphoma (PCNSL) depend on the area of CNS involved. Regional neurological impairments, neuropsychiatric symptoms, seizures, and elevated intracranial pressure presenting as headache, nausea, and vomiting are among the manifestations of brain involvement. PCNSL typically causes isolated intramedullary nodules to appear in the spine. Asymmetric sensory alterations, weakness in limbs, and bowel and urinary bladder abnormalities may also occur in PCNSL. Reduced visual acuity, hazy vision, and floaters can be caused by ophthalmic infiltration by PCNSL. PCNSL sufferers may experience vague cognitive or behavioral abnormalities in a week or months.
What Are the Imaging Features of Primary Central Nervous System Lymphoma?
A CT hyperdense strongly enhancing mass, T1 hypointense, T2 iso- to hypointense, bright homogenous gadolinium-enhancing lesion, limited dispersion on magnetic resonance imaging (MRI) and subependymal elongation and traversing of the corpus callosum are the classic imaging appearances of primary CNS lymphomas.
This characteristic pattern is useful for diagnosis; however, it is primarily seen in patients who are not immunocompromised and are not treated, who have diffuse large B-cell lymphoma, and who are EBV-negative. In individuals with immune deficiency, primary central nervous system lymphoma manifests in varied appearances.
Computed Tomography:
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A CT (computerized tomography) scan creates an in-depth picture of the body's soft tissue and bones by scanning it with X-rays. A physician can find out whether the cancer has progressed outside of the central nervous system with a CT scan.
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70 percent of primary CNS lymphomas on CT are hyperattenuating.
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PCNSL demonstrates enhancement, and the presence of hemorrhage (bleeding) is quite rare.
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Additionally, CT helps to locate the presence of multiple lesions in individuals with HIV or AIDS.
Magnetic Resonance Imaging:
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Magnetic resonance imaging (MRI) scans the human body using radio waves and magnets to create an intricate computer image of the interior organs. To improve the visibility of the cancer, the physician may inject patients with a harmless chemical called gadolinium. Gadolinium gathers surrounding cancer cells after it enters the body, which increases their visibility on a computer.
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In T1 weighted images, PCNSL usually appears hypointense (darker) to gray matter.
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Peripheral ring augmentation may be observed in immunocompromised individuals, more commonly those with HIV and AIDS.
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In T2, weighted images show varying features. Most people have isointense to hypointense gray matter.
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Isointense is seen in 33 % of cases, hypointense in 20 %, and hyperintense (brighter) between 15 % and 47 % of cases. Hyperintense is typically seen in lymphomas where necrosis is present.
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In susceptibility-weighted imaging (SWI), areas of hemorrhage are mostly seen.
Nuclear Medicine:
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Thallium-201 Scintigraphy - Greater uptake is seen in primary CNS lymphoma.
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Fluorine-18 FDG PET (Fluorodeoxyglucose Positron Emission Tomography) and Carbon-11 Methionine PET - Greater uptake is seen in primary CNS lymphoma.
How Is Primary Central Nervous System Lymphoma Diagnosed?
A complete neurological examination (a physical examination to find out any illness that is affecting the brain, spinal cord, and nerves), including an assessment of cognitive function, an eye examination, a physical examination to know about the lymph node status and an evaluation of the testes in older males, should be included in PCNSL diagnosis. The assessment of the eyes and testes is important because PCNSL usually tends to relapse in these places. Recurrence at other places is less common. In PCNSL, tissue biopsy is considered to be the benchmark for diagnosis. It is crucial to collect the biopsy before administering any corticosteroids.
How Is Primary Central Nervous System Lymphoma Treated?
Primary central nervous system lymphoma treatment includes -
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Radiation Therapy: Strong energy beams are used in radiation therapy to kill or stop cancer cell growth. Whole-brain radiation is one of the most used radiation therapies for CNS lymphoma symptoms. Radiation therapy is used to kill cancer cells all over the brain. Additionally, the radiation may harm healthy cells, impairing brain function. Talk to the doctor about the advantages and disadvantages of this therapy.
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Chemotherapy: Chemotherapy kills cancer cells using medication. Methotrexate is the medication frequently used to treat PCNSL.
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Steroid Therapy: This uses corticosteroids or other steroids to decrease inflammation in the body.
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Target Therapy: Rituximab and Ibrutinib are target therapy drugs used for PCNSL.
A low-grade tumor may respond well to local treatment consisting of surgical resection and radiation therapy, potentially leading to prolonged survival. In individuals with high-grade malignancies or recurrence, whole-brain irradiation could be added with chemotherapy.
Conclusion
Because of the risky nature of primary CNS lymphoma, individuals should have a personalized treatment plan and be closely monitored. Collaborating closely with a care team that has previously treated lymphomas or CNS malignancies is crucial. Chemotherapy with Methotrexate is a standard mode of treatment for PCNSL. The prognosis of this condition depends on the individual’s age, immune status, overall health, and the site of the tumor.
