Lung carcinoma presenting as multiple cystic lesions in the brain.

Eighty percent of brain metastases occur after the diagnosis of cancer has been established. A smaller number of cases are diagnosed synchronously with the primary site of malignancy. The majority of metastatic brain tumors present as small, well circumscribed densely enhancing masses with surrounding vasogenic edema. Cystic lesions are less common and when present raise the possibility of other disease processes affecting the brain. We report a case of cystic brain metastasis preceding the diagnosis of lung cancer in a patient with no systemic manifestations of malignancy, emphasizing the importance of clinical suspicion and histologic confirmation in determining treatment and predicting outcome.