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Secretory meningioma. A distinct subtype of meningioma
Abstract:
Six meningiomas with abundant hyaline inclusions (pseudopsammoma bodies) were studied. As seen by light and electron microscopy, hyaline inclusions are composed of material of varying structures located in intracellular lumina lined by microvilli. A remarkable pericytic proliferation within the vessel walls was found in five cases. In all six cases, immunohistochemical examination for multiple antigens showed positive staining for carcinoembryonic antigen and epithelial membrane antigen in inclusions and surrounding cells. Weak positivity was found for keratin and secretory component in five cases and for alpha-1-antitrypsin and IgM in four cases. It is concluded that secretory meningioma is a distinct type of meningioma, usually meningothelial in type. It shows characteristic light-microscopic, ultrastructural, and immunohistochemical features of epithelial and secretory differentiation with accumulation of secretory material in the form of hyaline inclusions; marked vascular pericytic proliferation is also frequently present.
Insights
Secretory meningioma, a distinct tumor type, features unique hyaline inclusions and pericytic proliferation. Immunohistochemistry confirms epithelial and secretory differentiation, aiding diagnosis.
Area of Science:
- Neurosurgery
- Pathology
- Oncology
Background:
- Meningiomas are common primary tumors of the central nervous system.
- Hyaline inclusions, or pseudopsammoma bodies, are characteristic but not fully understood features in some meningiomas.
Purpose of the Study:
- To characterize the ultrastructural and immunohistochemical features of meningiomas with abundant hyaline inclusions.
- To determine if these features define a distinct subtype of meningioma.
Main Methods:
- Light and electron microscopy were used to examine tumor histology.
- Immunohistochemistry was performed for carcinoembryonic antigen, epithelial membrane antigen, keratin, secretory component, alpha-1-antitrypsin, and IgM.
Main Results:
- Six meningiomas showed abundant intracellular hyaline inclusions.
- Positive staining for carcinoembryonic antigen and epithelial membrane antigen was observed in inclusions and surrounding cells.
- Pericytic proliferation within vessel walls was noted in five cases.
Conclusions:
- Secretory meningioma is a distinct subtype, typically meningothelial.
- It exhibits characteristic light microscopic, ultrastructural, and immunohistochemical evidence of epithelial and secretory differentiation.
- Accumulation of secretory material as hyaline inclusions and vascular pericytic proliferation are key features.