Leptomeningeal Metastases Differential Diagnoses

Updated: Oct 27, 2021
  • Author: Herbert H Engelhard, III, MD, PhD, FACS, FAANS; Chief Editor: Stephen A Berman, MD, PhD, MBA  more...
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Diagnostic Considerations

New signs or symptoms (particularly when multifocal) may represent progression of leptomeningeal metastases (LM) but may need to be distinguished from parenchymal disease (primarily brain) and or epidural metastases. Of patients with LM, 30–40% will also have brain metastases.

LM may also coexist with paraneoplastic syndromes or the adverse effects of chemotherapy or radiation. Signs of meningeal irritation may also be caused by infection. LM can be difficult to distinguish from subacute or chronic meningoencephalitis caused by tuberculosis or fungus. In these diseases, CSF findings may also show moderate mononuclear pleocytosis, elevated protein and decreased glucose (as described below). However, patients with LM usually are afebrile, and their neurologic symptoms appear earlier in the disease course with a preserved level of consciousness, rather than later with depressed mental status as in tubercular or fungal meningoencephalitis.

Intradural extramedullary spinal metastases (IESM) may be a separate phenomenon from LM. Proposed diagnostic criteria for IESM include: solid tumors located within the intradural extramedullary space, the absence of other leptomeningeal lesions seen on full-spine injected magnetic resonance imaging, and the absence of malignant cells in CSF. According to one study, the median overall survival was significantly higher for IESM patients (732 days) than for patients with LM (53 days). [15]

Differential Diagnoses