Adamantinomatous craniopharyngioma: pathology, molecular genetics and mouse models.

Adamantinomatous craniopharyngiomas (ACPs) are histologically benign but clinically aggressive epithelial tumours of the sellar region that are associated with high morbidity and occasional mortality. Research from the last 3 years has provided important insights into the molecular and cellular pathogenesis of these tumours. It has become established that mutations in CTNNB1 (encoding β-catenin), leading to the over-activation of the WNT pathway, underlie the molecular aetiology of human ACP. Interestingly, the effect of these mutations is restricted to a small number of tumour cells, mostly forming clusters, which recent research has shown to be critical for tumorigenesis in mice and humans. Several pathways have been found to be activated in these clusters including the epidermal growth factor receptor and the sonic hedgehog pathways, offering potential therapeutic targets. A novel and unexpected role for pituitary stem cells has been proposed, which is fundamentally distinct from the cancer stem cell paradigm. The study of these benign tumours could reveal important insights into general mechanisms underlying the initial steps of tumorigenesis and facilitate novel tools to improve managements of the patients.