Serial FDG PET/CT Findings in a Patient With Seronegative Neuroborreliosis After Treatment With Rituximab for a Follicular Lymphoma.

Published data concerning the semiology of neuroborreliosis at FDG PET/CT is scarce, and most reported cases with acute onset of neurological symptoms did not exhibit significant metabolic abnormalities. This 60-year-old man with follicular lymphoma achieved a complete response after 6 cycles of R-CHOP. Two weeks after the last injection, he developed afebrile headaches, neck pain, and paresthesia in his fingers, later followed by a brutal left peripheral facial palsy. FDG PET/CT demonstrated an increased metabolism of the cerebellum and of the cervical spinal cord, which completely resolved after treatment with doxycycline for 3 weeks. This is the first case report exhibiting serial metabolic changes at FDG PET/CT in the central nervous system during the evolution of the disease. This case illustrates the risks of lympho-depletion in patients treated with rituximab and highlights the value of PCR for Borrelia in the CSF in patients with false-negative Borrelia serology.