Pediatrik Kriptojenik Nörolojik Hastalıklarda İnsizyonel Beyin Biyopsisinin Tanıya Katkısı

Abstract

SUNGUR, E. The Diagnostic Contribution of Incisional Brain Biopsy in Pediatric Cryptogenic Neurological Diseases. Hacettepe University Faculty of Medicine, Department of Pediatrics, Medical Specialty Thesis, Ankara-2026. Cryptogenic neurological diseases pose significant diagnostic challenges in childhood due to their broad differential diagnosis spectrum and heterogeneous clinical course. In cases where diagnostic uncertainty persists despite clinical evaluation, laboratory investigations, cerebrospinal fluid analysis, and neuroimaging studies, brain biopsy may contribute to both the diagnostic process and clinical management. The aim of this study was to evaluate the diagnostic contribution and impact on clinical management of brain biopsy in pediatric cryptogenic neurological diseases, and to identify factors that may influence its diagnostic yield. In this study, pediatric patients evaluated by the Division of Pediatric Neurology at Hacettepe University İhsan Doğramacı Children’s Hospital between January 1, 2000 and December 1, 2024, whose brain tissue specimens were examined by the Department of Medical Pathology at Hacettepe University Faculty of Medicine, were retrospectively reviewed. A total of 892 pathology reports were screened, and 41 patients who underwent 45 brain biopsies for cryptogenic neurological disease were included in the study. Brain biopsy contributed to the diagnosis in 51.1% of cases by confirming the presumed diagnosis or leading to a diagnostic change, while diagnostic change alone was observed in 6.7% of biopsies. Its impact on management was higher than its diagnostic contribution, influencing management in 68.9% of biopsies. Diagnostic contribution differed significantly across final diagnostic groups; diagnostic yield was higher in neoplastic, infectious, and vasculitic processes, whereas it was more limited in metabolic/neurodegenerative diseases and immune-mediated encephalitis (p=0.002). Diagnostic change was more frequent in vasculitic processes; in these cases, vasculitis had not been included among the pre-biopsy differential diagnoses (p=0.008). The effect on clinical management also differed significantly across final diagnostic groups (p<0.001); clinical impact was particularly high in neoplastic, infectious, vasculitic, and immune-mediated processes, while it was limited in metabolic/neurodegenerative diseases. The presence of contrast enhancement on brain magnetic resonance imaging (p=0.005), the dominant involved compartment of the lesion (p=0.012), and a shorter interval between symptom onset and biopsy (p=0.005) were significantly associated with the diagnostic contribution of biopsy. No statistically significant association was found between diagnostic contribution and pre-biopsy treatment, biopsy technique (open/stereotactic), or biopsy type (incisional/excisional). The biopsy-related complication rate was 6.7%, and no biopsy-related mortality was observed. A borderline significant association was found between complication development and the anatomical biopsy site (p=0.050), whereas biopsy technique, biopsy type, and the patient’s clinical status at the time of biopsy were not significantly associated with complications. In conclusion, brain biopsy in pediatric cryptogenic neurological diseases is a feasible procedure with an acceptable safety profile that can provide substantial diagnostic and clinical benefit, particularly in the presence of targetable and contrast-enhancing lesions and when performed in a timely manner.

Keywords: cryptogenic neurological disease, brain biopsy, diagnostic contribution, clinical management, complication.