leptomeningeal enhancement
Abnormal contrast enhancement of the brain and spinal cord surface membranes on MRI, often indicating tumor spread or infection.
Full Definition
Leptomeningeal enhancement refers to abnormal gadolinium enhancement of the pia mater and arachnoid membrane (leptomeninges) visible on contrast-enhanced MRI studies. In neuro-oncology, this finding often indicates leptomeningeal metastasis (carcinomatosis or lymphomatosis), where tumor cells have spread to the cerebrospinal fluid and meningeal surfaces. This can occur with primary brain tumors (particularly high-grade gliomas, medulloepitheliomas, or germinomas) or systemic cancers (breast, lung, melanoma). The enhancement pattern may be linear, nodular, or diffuse, and can involve both brain and spinal surfaces. Diagnosis typically requires CSF analysis with cytology, and the finding significantly impacts prognosis and treatment planning.
Usage
Usage note: Describe pattern and distribution when reporting.
In Context
- "Post-contrast MRI demonstrated extensive leptomeningeal enhancement throughout the posterior fossa." — Radiology report
- "The presence of leptomeningeal enhancement warranted urgent CSF analysis." — Clinical decision