Lyme disease is a tick-borne infection caused by Borrelia burgdorferi sensu latu. Neuroborreliosis is reported in approximately 10% of patients with Lyme disease. We report a patient with central nervous system (CNS) large vessel vasculitis, ischemic stroke, and tumefactive contrast-enhancing brain lesions, an unusual complication of neuroborreliosis. A 56-year-old man presented with headache and disorientation for 1 month. Magnetic resonance imaging revealed basal meningitis with rapidly progressing frontotemporoinsular edema and (peri)vasculitis. Transcranial ultrasound confirmed stenosed medial cerebral arteries. [18 F]GE-180 microglia positron emission tomography (PET) showed frontotemporoinsular signal more pronounced on the right. [18 F]FET amino acid PET demonstrated low tracer uptake, suggesting an inflammatory process. Cerebrospinal fluid (CSF) showed lymphomonocytosis (243/μl), intrathecal anti-Borrelia IgM (CSF/serum index = 15.65, normal < 1.5) and anti-Borrelia IgG (CSF/serum index = 6.5, normal < 1.5), and elevated CXCL13 (29.2 pg/ml, normal < 10 pg/ml). Main differential diagnoses of neurotuberculosis and perivascular CNS lymphoma were ruled out by biopsy and Quantiferon enzyme-linked immunosorbent assay. Ceftriaxone (28 days), cortisone, and nimodipine (3 months) led to full recovery. Neuroborreliosis is an important differential diagnosis in patients with CNS large vessel vasculitis and tumefactive contrast-enhancing brain lesions, mimicking perivascular CNS lymphoma or neurotuberculosis as main neuroradiological differential diagnoses. Vasculopathy and cerebrovascular events are rare in neuroborreliosis but should be considered, especially in endemic areas.
