Approaches to supratentorial brain tumours in children.

The differential diagnosis of supratentorial brain tumours in children can be challenging, especially considering the recent changes to the WHO classification of CNS tumours published in 2021. Many new tumour types have been proposed which frequently present in children and young adults and their imaging features are currently being described by the neuroradiology community. The purpose of this article is to provide guidance to residents and fellows new to the field of paediatric neuroradiology on how to evaluate an MRI of a patient with a newly diagnosed supratentorial tumour. Six different approaches are discussed including: 1. Tumour types, briefly discussing the main changes to the recent WHO classification of CNS tumours, 2. Patient age and its influence on incidence rates of specific tumour types, 3. Growth patterns, 4. Tumour location and how defining the correct location helps in narrowing down the differential diagnoses and 5. Imaging features of the tumour on DWI, SWI, FLAIR and post contrast sequences.

Rathke's cyst with xanthogranulomatous change or chronic cystic craniopharingioma? A rare case.

A 9-year-old girl presented to our neurosurgery clinic complaining of visual disturbances for a week. Magnetic resonance imaging showed an extensive sellar lesion with suprasellar involvement and compression of the optic chiasm. Based on these findings, a cystic craniopharyngioma, a pituitary macroadenoma and - less likely - a Rathke's cleft cyst were considered as differential diagnoses. In view of the progressive loss of vision, the parents agreed to resection of the lesion through an endoscopic endonasal transtubercular approach, with the aim of a gross total resection. Microscopic examination revealed that the lesion was cystic, surrounded by an epithelium that was partly composed of columnar ciliated cells with interspersed mucous cells and partly had a flattened appearance. The observed findings were complex to interpret: if, on the one hand, the clinical-surgical and neuroradiologic data suggested a craniopharyngioma, this hypothesis was not supported by the microscopic data, because the presence of columnar ciliated epithelium associated with mucous cells was a microscopic feature inconsistent with a craniopharyngioma and was instead consistent with a Rathke's cleft cyst, a histologic diagnosis that was made. The incidence of Rathke's cleft cyst, which mimics clinical and neuroradiologic aspects of craniopharyngiomas, is extremely unusual, as only 2 cases have been described in the literature.