Two-decade clinicopathological spectrum of gliomas at a tertiary center in LMIC: histological profile and the molecular diagnostic gap

Abstract

Diffuse gliomas are the most common malignant primary central nervous system (CNS) tumors, and contemporary World Health Organization (WHO) criteria require molecular markers, mainly isocitrate dehydrogenase (IDH) status and 1p/19q codeletion, for an integrated diagnosis. Access to these tests remains uneven in low- and middle-income settings. Data describing the glioma spectrum and the practical impact of limited molecular testing in Jordan are scarce. We retrospectively retrieved all glioma-related surgical pathology specimens accessioned between 2003 and 2024 at a tertiary academic center in Jordan through a structured text search. Histological category, WHO grade, anatomic site, immunohistochemical (IHC) profile, Ki-67 index, and documented IDH/1p-19q status were extracted from the free-text reports. After exclusion of non-neoplastic, non-glial, and unclassifiable records, 430 specimens from 332 patients formed the analytic cohort. Ki-67 across grades was compared with the Kruskal-Wallis test and categorical age associations with the chi-square test. The median age was 48 years (IQR 28-63; range 3-98) with a male predominance (male-to-female ratio 1.30). Glioblastoma was the most frequent diagnosis (174/430; 40.5%), followed by non-pilocytic astrocytoma (17.9%) and unspecified diffuse glioma (12.8%). The Ki-67 index increased significantly across WHO grades (median 3%, 2%, 20%, and 30% for grades I-IV; Kruskal-Wallis p < 0.0001). An actual IDH result was documented for only 10 specimens (2.3% overall; 3.0% of 329 diffuse gliomas), while reports explicitly noted that testing was indicated but unavailable in a further 17.4%. Glioblastoma was almost exclusive to adults and pilocytic astrocytoma to children (both p < 0.0001). Annual case volume rose from approximately 15 to 25 specimens per year, yet documented IDH results appeared only after 2017 and in fewer than 5% of recent specimens. Over two decades, gliomas at our center were diagnosed predominantly on morphology and a limited IHC panel. The near-absence of molecular results means the large majority of diffuse gliomas cannot be fully classified by current WHO standards, a concrete diagnostic-capacity gap with direct implications for prognostication, treatment stratification, and trial eligibility. The findings support investment in accessible molecular neuropathology, including surrogate IHC and regional referral testing.