ABSTRACT
Introduction Patients with intracranial metastases far outnumber those who suffer from primary intracranial tumors. In the USA new symptomatic primary intracranial tumors do not exceed 30 000 per year, whereas symptomatic intracranial metastases number greater than 100 000 per year. The diagnosis of a brain metastasis may be difficult for several reasons. (1) Metastases can affect any central nervous system (CNS) location, mimicking both the clinical and imaging findings of primary intracranial tumors (Fig. 13.1). (2) Metastases are increasing in frequency as the first site of relapse in patients whose cancers have apparently been ‘cured’1 or are under good systemic control.2 (3) Symptoms and signs of brain metastases may appear before the primary tumor has been discovered.3 In some instances, a patient may suffer multiple symptomatic intracranial metastases but the primary cancer is never found even after an extensive search.3 (4) Primary brain tumors are more common in patients who have suffered other cancers than they are in the general population. Examples include meningiomas in patients with breast cancer (Chapter 6) and gliomas in patients with Li-Fraumeni syndrome (Chapter 12). (5) Other CNS processes, such as brain abscesses, can mimic brain metastases and occur with increased frequency in patients with cancer. Radiographic
images often do not differentiate metastases from infection and diagnosis must be based upon the clinical situation and occasionally requires biopsy. For all these reasons, diagnoses other than metastases must be considered in cancer patients who develop intracranial mass lesions and, conversely, metastases must be considered in patients without known cancer who develop intracranial mass lesions. A comprehensive review of neurologic complications of cancer is available.4
