Focal leptomeningeal vascular anomalies on brain MRI: A mimic of leptomeningeal metastatic disease

Alexandre Boutet; Mikail Malik; Andrew Z Yang; Jurgen Germann; Samuel S Haile; Hyo Jin Son; Artur Vetkas; Vivek Pai; Warren P Mason; Gelareh Zadeh; Daniel M Mandell

doi:10.1093/nop/npae050

Focal leptomeningeal vascular anomalies on brain MRI: A mimic of leptomeningeal metastatic disease

Neurooncol Pract. 2024 Jun 7;11(6):772-778. doi: 10.1093/nop/npae050. eCollection 2024 Dec.

Authors

Alexandre Boutet¹, Mikail Malik², Andrew Z Yang³, Jurgen Germann^{4

3}, Samuel S Haile², Hyo Jin Son², Artur Vetkas³, Vivek Pai^{1

5}, Warren P Mason⁶, Gelareh Zadeh³, Daniel M Mandell¹

Affiliations

¹ Joint Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada.
² Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
³ Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada.
⁴ Krembil Brain Institute, Toronto, Ontario, Canada.
⁵ Division of Neuroradiology, Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada.
⁶ Department of Medicine, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada.

PMID: 39554785
PMCID: PMC11567751 (available on 2025-06-07)
DOI: 10.1093/nop/npae050

Abstract

Background: The diagnosis of leptomeningeal metastatic disease has major prognostic and therapeutic implications. We report 13 patients with a radiologically distinct kind of focal, enhancing leptomeningeal lesion on brain MRI that mimics leptomeningeal metastatic disease.

Methods: These patients were assessed at University Health Network (Toronto, Canada) between January 2001 and December 2023.

Results: Median age was 68 years (range, 55-78 years) and 10 patients were women. All patients had brain magnetic resonance imaging (MRI) including contrast-enhanced T2-weighted fluid attenuation inversion recovery (FLAIR) and T1-weighted spin echo sequences. MRI in all 13 patients showed a focal enhancing lesion located along the leptomeningeal surface of the brain. The MRI exams were reported as possible or likely leptomeningeal metastatic disease for the majority (9/13) of patients. Each lesion was curvilinear rather than sheet-like, and some lesions consisted of multiple connected/branching curvilinear structures with the appearance of abnormal vessels. The lesions were distinct from normal blood vessels. Some lesions had a visible connection with a nearby cortical vein. Follow-up contrast-enhanced brain MRI for 8/13 (62%) patients at a median of 3.9 years (IQR 2.4-6.6 years) showed all lesions were unchanged over time. Another 2/13 (15%) patients had clinical and CT brain follow-up after one year with no evidence of metastatic disease.

Conclusions: We describe a distinct kind of focal, enhancing leptomeningeal lesion on brain MRI that mimics metastatic disease. These lesions are likely a type of low-flow vascular anomaly. Their curvilinear/branching shape and intense enhancement particularly on T2-weighted FLAIR images distinguish these lesions from tumors.

Keywords: brain; brain neoplasms; decision making; magnetic resonance imaging.

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