ID #310 Infantile CNS Tumours (InfCT): histomolecular spectrum
Dhruva Maitra, Ayushi Sahay, Aekta Shah, Mamta Gurav, Omshree Shetty, Prakash Shetty, Aliasgar Moiyadi, Maya Prasad, Girish Chinnaswamy, Kajari Bhattacharya, Arpita Sahu, Archya Dasgupta, Abhishek Chatterjee, Vikas Singh, Tejpal Gupta, Sridhar EpariAbstract
Introduction
Infantile central nervous system (CNS) tumours (≤3 years) are histomolecularly distinct from those in older children.
Aim
To characterize the histomolecular spectrum of infantile CNS tumours diagnosed at our institution over the past decade.
Methods
We retrospectively collated histopathological, immunohistochemical, molecular, and clinicoradiological data for all primary CNS tumours diagnosed in children ≤3 years (2015–2024). Integrated diagnoses followed the WHO Classification of CNS Tumours, 5th edition.
Results
The cohort comprised 464 cases (≤1 year: n = 41 [8.8%]; >1–3 years: n = 423 [91.2%]); median age 28.1 months (IQR 19.1–37.3); 306 males and 158 females. Tumour locations were posterior fossa (n = 269, 58%), cerebral hemispheres (n = 91, 19.6%), suprasellar region (n = 43, 9.3%), pineal (n = 16, 3.4%), lateral ventricles (19, 4.1%), thalamus (7, 1.5%), and spinal (19, 4.1%). Gliomas, glioneuronal, and neuronal tumours predominated (n = 218, 47.0%), including low-grade glial/glioneuronal (n = 95, 43.5%), high-grade glial (n = 27, 12.4%), astrocytic NOS (n = 3, 1.4%), and ependymal (n = 93, 42.7%). Embryonal tumours constituted 199 (42.9%): medulloblastoma (n = 115), atypical teratoid/rhabdoid tumour (n = 45), embryonal tumour with multilayered rosettes (n = 22), and CNS embryonal tumour, NOS (n = 17). Choroid plexus tumours (n = 23) and pineoblastomas (n = 13) were uncommon; adamantinomatous craniopharyngioma (n = 4), germ cell tumours (n = 5), and meningioma (n = 2) were rare. Pilocytic astrocytoma was the most common entity (n = 78, 16.8%). Among 49 pilocytic astrocytomas with molecular data, BRAF alterations were detected in 31 (KIAA1549-BRAF fusions: 28; BRAFV600E: 3); 18 were negative. Ependymomas included posterior fossa group A (PF-A) as the most frequent subtype (40/69 posterior fossa) and supratentorial ependymoma, ZFTA-altered (12/24 supratentorial). Among medulloblastomas, SHH-activated/TP53-wildtype was most common (n = 42), followed by non-WNT/SHH Group 3 (n = 33).
Conclusion
In infants, gliomas/glioneuronal/neuronal tumours are the predominant WHO CNS5 family, with medulloblastomas the most frequent group overall; however, pilocytic astrocytoma is the single most common specific diagnosis. These data underscore age-specific histomolecular patterns with implications for diagnosis and targeted management.