Primary Brain Lymphomas
Incidence of primary brain lymphomas is increasing, particularly among immunocompromised patients and the elderly. Lymphomas tend to infiltrate the brain diffusely, often as multicentric masses adjacent to the ventricles, but may occur as solitary brain masses. Lymphomas may also occur in the meninges, uvea, or vitreous humor. Most are B-cell tumors, often immunoblastic. The Epstein-Barr virus may contribute to development of lymphomas in immunocompromised patients. Most patients do not develop subsequent systemic lymphoma.
MRI can suggest the diagnosis of primary brain lymphoma. However, MRI may be unable to distinguish cerebral toxoplasmosis (which is common among patients with AIDS) from lymphoma.
If there are meningeal signs, CSF is examined; it may contain lymphoma cells. In immunocompromised patients, Epstein-Barr virus DNA may be detected in CSF. If CSF does not contain lymphoma cells or Epstein-Barr virus DNA, guided-needle or open biopsy is required. Because lymphoma is initially highly sensitive to corticosteroids, giving these drugs just before biopsy may cause the lesion to disappear, resulting in a false-negative biopsy.
Staging of primary brain lymphomas involves imaging of the chest, abdomen, and pelvis; slit-lamp examination of the eye; and bone marrow biopsy to determine how far the tumor has spread.
Corticosteroids result in rapid improvement initially, but responses are short-term. There is no role for surgical excision except when herniation is impending. Multidrug chemotherapy regimens using high-dose IV methotrexate (1 g/m2 to 8 g/m2) may result in long-lasting responses. The addition of consolidation chemotherapy, consolidation whole-brain radiation therapy, or high-dose chemotherapy with stem-cell rescue probably improves survival.
Whole-brain radiation can cause clinically significant leukoencephalopathy, particularly in older patients.
Median survival in nonelderly patients is more than 5 yr.