What is CNS Lymphoma?

Lymphoma in the central nervous system can either originate in the nervous system or can spread to the nervous system from another part of the body. Whether the lesion originates in the nervous system (primary) or originates from without (secondary) the histology (appearance and patterns of the cells) and the clinical presentation are very much the same. The location of CNS lymphoma can be above the tentorium in the region of the cerebrum where it has a tendency to affect the frontal lobes, the deep nuclei and the brain tissue around the ventricular system. Below the tentorium, in the posterior fossa where the cerebellum and brain stem are located, the lymphoma tends to collect in tissue of the cerebellum. The incidence of CNS lymphoma is increasing in the last 10 years. This is thought to be due to several factors, most prominently immunosuppression with drugs so that patients will not reject transplanted organs in addition to the acquired immunodeficiencies syndrome (AIDS).

Who is most likely to have a CNS lymphoma?

The male to female ratio of CNS lymphoma is 1.5 to 1. Mean age and diagnosis is 52 years. However, in known immuno compromised patients this mean peak incidence age is 34 years. Conditions which can be associated with CNS lymphoma include collagen vascular disease, Epstein Barr virus infection, as well as immuno suppression.

What are the symptoms?

A patient with CNS lymphoma can present initially with signs of spinal cord compression with paraplegia or weakness of the lower extremities with loss of sensation and bladder and bowel function. The other major presentation for CNS lymphoma is of carncino matous meningitis which, as discussed elsewhere, is a syndrome frequently characterized by multiple cranial nerve palsies. The symptoms of CNS lymphoma can be non-focal and non-specific such as changes in the patients thinking and behavior or symptoms suggestive of increased intracranial pressure such as headache, nausea, vomiting and blurred vision. Some patients also have general seizures as their first symptom of CNS lymphoma. The other presentation of CNS lymphoma could be a focal deficit, meaning that one are of the brain is affected and the function of that area is the symptom. This would be weakness or numbness of one extremity or one side of the body, sparing the other. When examined by a physician the patient can be found to have non-focal, focal or combined focal and non-focal findings.

How is it diagnosed?

The diagnosis of CNS lymphoma is by imaging studies such as MRI scan. For an epidural collection a myelogram may be necessary. When working up a CNS lymphoma it is necessary to also rule out systemic lymphoma. This is done by examining the peripheral lymph nodes, the blood, urine, bone marrow (by biopsy), testicular ultrasound in men, and an ophthamalogical examination.

What is the treatment?

The treatment for CNS lymphoma begins with a biopsy to determine that this is in fact the lesion which should be treated. There are other causes of abnormalities on MRI scan particularly in the AIDS population that should not be confused with lymphoma or treated as lymphoma would be. Once a diagnosis of CNS lymphoma has been confirmed on the basis of a stereotactic biopsy, whole brain radiation should be administered. Chemotherapy so far has limited proven value in the treatment of this disease.