Pituitary adenomas are the most common tumours found in the sellar region and, when both functioning and non-functioning adenomas are combined, account for 7–15% of primary brain tumours in adults. Rarely, admixed or discrete groups of cells comprising two or more tumour subtypes are seen; the so-called ‘collision tumour’ [1]. We present a case of a 54-year-old woman with a growth hormone-secreting pituitary adenoma admixed with both ganglioglioma and gangliocytoma.