Role of 18F-FDG PET-CT in CNS Lymphoma-A Case Report

The actual role of 18F-FDG PET/CT in evaluating primary brain lymphoma is still an open issue. Brain lymphoma usually show elevated 18F-FDG uptake, often higher than other brain tumors or inflammatory processes, but the metabolic behavior of this lymphoma is not still understood. Central nervous system lymphoma is a rare non-Hodgkin lymphoma in which malignant (cancer) cells from lymph tissue form in the brain and/or spinal cord (primary CNS) or spread from other parts of the body to the brain and/or spinal cord (secondary CNS).A 55 year-old man presented with headache. Magnetic Resonance Imaging (MRI) revealed a well-enhanced mass lesion in the left frontal lobe. A surgical specimen obtained through left orbito-pterional craniotomy revealed a Diffuse Large B-Cell Lymphoma (DLBCL). 18F FDG PET-CT scan showed multiple hypodensehypermetabolic lesions in brain. Multiple hypodense focal hypermetabolic areas were seen in right frontal lobe, left frontal lobe and left temporal lobe. There was also a subcentimetrichypermetabolic sub-carinal lymph node. The activity was diminished on follow-up PET-CT after 8 courses of chemotherapy. This case indicates that FDG PET-CT scan can aid identify the atypical primary CNS lymphoma for staging workup and can be a useful tool to see treatment response.