Q: What is the most likely diagnosis? What differentials would you need to consider? show answer

A: Given the suprasellar epicentre, cystic nature and calcifications, a craniopharyngioma would be most likely. Other considerations include a teratoma, or a cystic brain tumour (the size of the lesion makes it difficult to localise well).

Q: What feature not present in this case, would push you towards the diagnosis of a teratoma? show answer

A: Macroscopic fat within the lesion, a common feature of teratomas.

Q: What are the two histological types of craniopharyngioma, and which would this be? show answer

A: The two types are adamantinomatous (typically paediatric) and papillary (typically adult). Additionally adamantinomatous is usually predominantly cystic and in 90% of cases demonstrate some calcification. As such this would be adamantinomatous.

Q: What MR spectroscopy feature is supportive of the diagnosis of craniopharyngioma? show answer

A: Cyst contents show a broad lipid spectrum, with an otherwise flat(ish) baseline.

Q: What is the usual T1 signal of cyst fluid in craniopharyngiomas? show answer

A: Signal intensity varies depending on cyst contents, and can appear hyperintense due to protein, blood products, and/or cholesterol (in the classic adamantinomatous type); in the papillary variety, solid components appear isointense on T1-weighted images.