Introduction
Primary Central Nervous System Lymphoma (PCNSL) is an extranodal
non-Hodgkin lymphoma (NHL) originating in brain tissue, spinal cord,
leptomeninges and vitreoretinal eye accounting for 3% to 5% of all
brain tumors and less than 1% of all NHLs. The 95% of PCNSLs are
B-cell lymphomas; T-cell lymphomas constitute the remaining
2-5%1. Pediatric PCNSLs are very rare (about 1%).
Cerebral hemisphere, basal ganglia, corpus callosum, brainstem and
cerebellum are the most common involved brain sites. Clinical
manifestations include headache, aphasia, sensory and motor deficits,
speech disorders, ataxia, seizures and short- term memory
difficulties2. ALCL is a peripheral T-cell lymphoma,
accounting for about 2-8% of all NHLs. Brain ALCL is a very rare
subtype of PCNSL. Mean age at diagnosis is 21 years and leptomeningeal
involvement occurs in 80% of cases as tan-white nodules on the dural
surface3. ALCL can be classified into ALK+ and ALK-
ALCL, according to the pattern of genetic abnormalities. ALK+ cases
generally occur in younger patients and have a more favorable prognosis
than ALK- cases, with two years survival rate of 71% and 22%
respectively3. ALCLs are hypointense on MRI T1 and
isointense to hyperintense on T2-weighted images, mainly occurring as
single or multiple supratentorial lesions. The enhancement pattern
doesn’t clearly distinguish it from meningiomas, metastasis or
gliomas4.