Skull and Meningeal Metastases

KEY FACTS

Imaging

• Enhancing lesion(s) with skull/meningeal destruction/infiltration

• Skull, dura, leptomeninges, arachnoid/subarachnoid, pia, and subgaleal

• Many manifestations: Smooth thickening, nodularity, loculation, lobulation, fungating masses

Top Differential Diagnoses

• Skull metastases: Surgical defect (burr hole, craniectomy), myeloma

• Dural metastases: Epidural/subdural hematoma, meningioma

• Leptomeningeal metastases: Subarachnoid hemorrhage, sarcoidosis, infectious meningitis

Clinical Issues

• 18% of patients with extracranial and intracranial malignancies

• Primary tumor never identified in 2-4%

• All metastases: May be asymptomatic and unsuspected clinically

• Headache is most common symptom (50%)

• CSF cytology often falsely negative

• Accuracy of single lumbar puncture (LP) is 50-60% but 90% after 3 attempts

• Bimodal → children (medulloblastoma & leukemia); adults (breast, lung, melanoma, prostate)

• Average age ~ 50 years (relatively young secondary pediatric cancer and young women with breast cancer)

• Entire neuraxis must be treated, as tumor cells are often widely disseminated throughout CSF

Diagnostic Checklist

• Both enhanced MR and LP should be performed, especially if initial test is negative

TERMINOLOGY

IMAGING