Large solitary cystic brain metastasis mimicking colloid cyst of the third ventricle

Metastatic lung adenocarcinoma to the brain is a common metastatic brain tumour [Won LLJ, Hyung KR, Moon CK, Chang RC. Metastatic mucinous adenocarcinoma mimicking cerebral haemorrhage. J Korean Neurosurg Soc 2003;34(3):252-3]. Brain metastases can occur at any location. However, metastases in the third ventricle are rare [Ozerk O, Ihsan S, Erkan K, Etem B. Intracranial metastasis of lung adenocarcinoma mimicking colloid cyst of the third ventricle. J Clin Neurosci 2006;13(4):487-9]. We report a case of metastatic lung adenocarcinoma to the brain mimicking a giant colloid cyst of the third ventricle.