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Intracellular inclusions in meningothelial meningioma. A histochemical and ultrastructural study
Abstract:
This is a study on the histochemical and electron microscope findings of the intracellular inclusions in a case of meningothelial meningioma of the frontoethmoidal region with orbital involvement. The inclusions are PAS-positive, diastase resistant, and stain strongly positive with the modified Morel-Sisley reaction for protein-bound tyrosine and weakly with dihydroxy-dinaphthyl-disulfide (DDD) for the demonstration of sulfhydryl (SH) and disulfide (S-S) groups of proteins. These staining reactions suggest the inclusions are composed of conjugated proteins (glycoproteins). Ultrastructurally, the inclusions are located within intracellular spaces lined by microvilli and are composed of granular material, usually forming a dense core that is intermixed with small vacuoles. Numerous desmosomes and whorls of tonofibrils are concentrated around them. Our findings support the view that the intracellular inclusions, which are rarely found in meningiomas, represent an active secretory product of the meningothelial cells rather than a degenerative or phagocytic process.
Insights
Intracellular inclusions in meningioma are likely a secretory product of meningothelial cells, not a degenerative process. These findings offer new insights into meningioma cell biology.
Area of Science:
- Neurosurgery
- Pathology
- Oncology
Background:
- Meningiomas are tumors arising from meningothelial cells.
- Intracellular inclusions are rarely observed in meningiomas.
- Understanding the nature of these inclusions is crucial for diagnosis and treatment.
Observation:
- Histochemical analysis revealed inclusions are PAS-positive and diastase-resistant.
- Staining indicated the presence of protein-bound tyrosine and sulfhydryl/disulfide groups.
- Electron microscopy showed inclusions within microvilli-lined spaces, composed of granular material and vacuoles.
Findings:
- The inclusions are composed of conjugated proteins, likely glycoproteins.
- Ultrastructural features include desmosomes and tonofibrils surrounding the inclusions.
- The inclusions appear to be an active secretory product of meningothelial cells.
Implications:
- This study challenges the notion of inclusions as degenerative or phagocytic.
- Findings suggest a potential role for these inclusions in meningioma pathogenesis.
- Further research may elucidate the specific function and significance of these secretory products.