A 42-year-old immune-competent woman with orbital pseudotumor and pres
umed intracranial extension into the temporal lobe responded well clin
ically and radiologically to high-doses of corticosteroids. Five month
s later, she developed worsening headaches and recurrence of the tempo
ral lobe lesion. Biopsy revealed a central nervous system (CNS) lympho
ma with severe reactive gliosis abutting an area of subarachnoid lymph
ocytic infiltrate.