Ectopic Meningioma
Cyril Fisher, MD, DSc, FRCPath
Lester D. R. Thompson, MD
Key Facts
Terminology
Benign neoplasm of meningothelial cells
Clinical Issues
Can present in skin of scalp
Approximately 0.2% of sinonasal tract and nasopharynx tumors
M:F = 1:1.2
Women older by more than a decade
About 20% recur
5-year survival is 78% in scalp tumors
Image Findings
Must exclude direct CNS extension
Microscopic Pathology
Infiltrative growth of neoplastic cells, including soft tissue and bone
Meningothelial (syncytial) lobules of neoplastic cells without distinct borders
Whorled architecture, psammoma bodies
 A nasal cavity tumor shows intact mucosa overlying a syncytial-like neoplastic meningothelial cell proliferation  . The nuclei are uniform, and the cells show moderate amounts of cytoplasm. |
 The meningothelial cells are arranged in a distinctive whorled pattern, with uninvolved surface squamous epithelium  . Cell boundaries are indistinct. |
TERMINOLOGY
Definitions
Benign neoplasm of meningothelial cells in scalp, nasal cavity, sinonasal tract, nasopharynx, or lung
ETIOLOGY/PATHOGENESIS
Pathogenesis
Arachnoid cells from arachnoid granulations or pacchionian bodies lining sheaths of nerves and vessels through skull foramina
CLINICAL ISSUES
Epidemiology
