Spontaneous regression of a large lateral ventricle cyst: illustrative case

Colloid cysts (CCs) are rare benign lesions, typically found in the third ventricle. While most CCs remain asymptomatic, they can occasionally cause significant symptoms such as headaches, visual disturbances, seizures, and, in rare cases, sudden death.

This article reports a rare case of spontaneous regression of a CC located in the lateral ventricle. After remaining stable for more than 4 years, the cyst underwent spontaneous regression.

This case challenges existing ideas regarding the origin and regression mechanisms of CCs. It demonstrates that lateral ventricle CCs can spontaneously regress, highlighting the need to reconsider their embryological origin, their natural history, and the role of surgery. However, the diagnosis of CC has been solely radiological, and other forms of tumor-like cystic lesions, such as neuroepithelial or ependymal cysts, should be taken into consideration. https://thejns.org/doi/10.3171/CASE25319.