Review Question - QID 210003

This patient is presenting with new onset seizures in the setting of a significant smoking history and weight loss concerning for small cell carcinoma of the lung.

The most common cause of a CNS tumor is a metastatic lesion rather than a primary lesion (such as glioblastoma multiforme). The most common cause of a metastatic lesion to the CNS is from lung cancer. Other common causes are breast cancer, melanoma, renal cell carcinoma, and colorectal carcinoma. Presenting symptoms of metastases to the CNS include headaches, nausea/vomiting, seizures, and focal symptoms.

Incorrect Answers:
Answer 1: Glioblastoma multiforme represents a primary CNS tumor which is a less likely cause of a CNS malignancy when compared to metastatic lung cancer.

Answer 2: Hyponatremia could cause seizures, in particular if it is treated too quickly; however, this is unlikely given this patient's age, risk factors, and the likely slow onset of hyponatremia (if this patient even suffers from it).

Answer 3: Infiltrating ductal carcinoma of the breast is a possible malignancy in this patient; however, epidemiologically lung cancer is more likely to metastasize to the brain. This patient's smoking is a risk factor for both lung cancer and breast cancer.

Answer 4: Primary seizure disorders typically do not present in elderly patients spontaneously without a predisposing incident (trauma).

Bullet Summary:
The most common cause of malignancy in the brain is metastatic lung cancer.