The Neurosurgical Challenge of Primary Central Nervous System LymphomaDiagnosis: A Multimodal Intraoperative Imaging Approach to OvercomeFrameless Neuronavigated Biopsy Sampling Errors br

Background:Intracranial lymphoma remains a challenging differential diagnosis in daily neurosurgical prac-tice. We analyzed our early experiencewith a surgical series of frameless neuronavigated biopsies in PrimaryCNS Lymphomas (PCNSLs), highlighting the importance of using an intraoperative combined imaging pro-tocol (5-ALAfluorescence, i-CT and11C-MET-PET) to overcome potential targeting errors secondary totumor volume reduction after corticosteroid therapy.Materials and Methods:AllpatientstreatedforPCNLSsat our center in a 24-month period (1/1/2019 to 31/12/2020) were analyzed. Our cohort included 6 patients(4 males), with a median age of 67 years (59-82). A total of 45 samples were evaluated for correlation betweenintraoperativefluorescence and pathologicalfindings. 39 samples biopsy were evaluated.Results:54% samplesshowedacleardiagnosisofPCNSL.64%ofsampleshadalavalikefluorescence. i-CT scan showed tumorvolume changes, in comparison to preoperative MRI, inall cases and helped in planning correct trajectorieson updated imaging; after biopsy i-CT confirmed sampling accuracy and excluded procedural complicationsin all cases.Conclusions:We believe that the use of a multimodal intraoperative imaging approach overcomesthe demonstrated PCNSL morphological changes causedby corticosteroid therapy and gives a reliable tissuediagnosis by frameless biopsy.