Neuroendocrine tumour arising inside a tailgut cyst

Tailgut cysts are rare benign retrorectal cysts arising from persistent remnants of an embryonic hindgut. Malignant transformation inside this lesion is very uncommon and occurrence of neuroendocrine tumours in this context is extremely rare. We report the case of a 56-year-old woman who underwent surgical excision of a presacral tailgut cyst, which was found incidentally to include a neuroendocrine tumour.