BACKGROUND
The optimal diagnosis and management of patients with brain tumors currently uses the 2021 WHO integrated diagnosis of histomorphologic and molecular features. However, neuro-oncology practice in resource-limited settings usually relies solely on histomorphology. This study aimed to classify glioma cases diagnosed in the Department of Anatomic and Molecular Pathology, Lagos University Teaching Hospital (LUTH), using the WHO 2021 classification.
METHODS
Fifty-six brain tumors from 55 patients diagnosed as glioma between 2013 to 2021 were re-evaluated for morphologic diagnosis at Mayo Clinic, Rochester. Molecular features were determined from formalin-fixed paraffin-embedded (FFPE) tissue using immunohistochemistry (IHC) for IDH1-R132H, ATRX, BRAF-V600E, p53, Ki67, and H3-K27M, OncoScan chromosomal microarray for copy number, targeted next generation sequencing (NGS) for mutation and fusion and methylation array profiling.
RESULTS
Of 55 central nervous system tumors, three were excluded on histomorphologic re-evaluation for not being of glial or neuroepithelial origin. Of the remaining 52 patients, the median age was 20.5 years (range: 1 to 60 years), 38(73%) were males and 14(27%) were females. Seventy-one percent of the gliomas evaluated provided adequate DNA from archival FFPE tissue blocks. After applying the 2021 WHO diagnostic criteria the initial morphologic diagnosis changed for 35% (18/52) of cases. Diagnoses of five (9.6%) gliomas were upgraded, and seven (14%) were downgraded.
CONCLUSION
This study shows that incorporation of molecular testing can considerably improve brain tumor diagnoses in Nigeria. Furthermore, this study highlights the diagnostic challenges in resource-limited settings and what is at stake in the global disparities of brain tumor diagnosis.