Primary CNS Lymphoma
Definition: Primary Central Nervous System (CSN) Lymphoma is a malignant, or high-grade brain tumor of B cell origin. It can occur in both immuno-competent patients as well as patients with immunodeficiency (eg. HIV positive).
Age/Sex: The mean age is about 50 years except for HIV+ve or immuno-deficient patients who are mostly in the late 20s.
Presentation: Headaches, seizures, blurred vision, cranial neuropathy and focal neurological symptoms (hemiparesis, aphasia etc).
Diagnosis: MRI is the diagnostic modality of choice. The tumor shows intense contrast enhancement with gadolinium. The lesions are usually cerebral and single in about 2/3rds of patients. HIV+ve patients usually have multiple lesions. The use of steroids prior to imaging may cause the lesion to temporarily disappear, hindering diagnosis. Stereotactic Biopsy or Image-guided craniotomy and biopsy is usually needed for histopathological diagnosis. The therapeutic role of aggressive surgical resection is limited.
Treatment: Image-guided /Computer-aided Craniotomy and aggressive tumor resection is rarely done as it can make patients worse and does not have a major impact on survival. The exception is for large tumors with mass effect and impending herniation. Radiation has an important role as primary CNS lymphoma is very radiosensitive. Stereotactic radiation and NeuroTomotherapy are more advanced forms of radiation. Chemotherapy especially intrathecal chemotherapy through an Ommaya reservoir is a mainstay of treatment. MTX (methothrexate) is the agent of choice.