South African Journal of Radiology

Meningiomas, the most common primary intracranial tumours (accounting for 36% of central nervous system neoplasms), typically present as well-circumscribed, extra-axial masses with homogeneous enhancement, dural tails and hyperostosis on imaging. However, 15% show atypical features that can mimic gliomas, metastases or abscesses, posing diagnostic challenges. This case series present seven histologically confirmed meningiomas illustrating atypical imaging appearances, identified retrospectively from the institutional teaching archive. The cases include intraventricular, septated cystic, perineural spread, circumscribed low T2 or FLAIR signal, frond-like low T2 or FLAIR signal, peritumoural cystic and radiation-induced meningiomas. All were WHO grade 1, except one radiation-induced grade 2 tumour. Key atypical imaging findings included heterogeneous enhancement, non-suppressing cystic components on FLAIR, brain invasion, absent dural tail and perilesional oedema. Although these features suggested higher-grade behaviour, they did not correlate with the final histological grade. Atypical imaging features in meningiomas may closely mimic more aggressive pathologies and do not reliably predict histological grade. Recognition of these variants is essential for accurate diagnosis and appropriate management.
Contribution: This case series expands the recognised imaging spectrum of meningiomas by demonstrating diverse atypical appearances that closely mimic other intracranial pathologies. Importantly, it highlights the discordance between aggressive imaging features and histological grade, reinforcing that atypical morphology should not be equated with higher-grade disease.