Giant, lamellated colloid cyst: 'Russian-Doll' appearance.

Colloid cysts (CCs) are usually small, benign lesions located at the foramen of Monro. They usually grow to a size of 1-3 cms. We have described here a giant colloid cyst of size 6 x 5.2 x 4.4 cm with a unique radiological appearance of multiple concentric layers with different intensities which has not been described before. This unusual appearance is most probably due to the variation of hydration between the different layers with gradually decreasing concentration of protein from centre to periphery, which correlated well with intraoperative and histopathological findings.