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Malignant meningioma with a new intracytoplasmic inclusion body
1Department of Neurosurgery, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan.
Abstract:
A 55-year-old man presented with a frontal mass lesion, which histologically consisted of pleomorphic tumor cells with necrotic foci and abundant mitotic figures, showing a meningothelial pattern focally. In addition, many eosinophilic round- or irregular-shaped bodies were seen not only in tumor cell cytoplasm but also in between the tumor cells. By electron microscopy, the tumor cells showed a minimal adherence to each other and the intercellular spaces were wide. Tumor cells had numerous branching cytoplasmic processes and some of them were united by desmosomal junctions. These features suggested that the tumor was a malignant variety of arachnoid trabecular cell meningioma. The inclusion bodies consisted of homogeneous fine granular material and were not surrounded by microvilli. This type of inclusion body has not been reported in meningiomas in the past. The significance and possible pathogenesis of the inclusions are discussed.
Insights
This study reports a rare malignant meningioma with unique eosinophilic inclusion bodies. Further research is needed to understand the significance and pathogenesis of these novel findings in meningioma.
Area of Science:
- Neuropathology
- Oncology
Background:
- Meningiomas are tumors arising from the meninges.
- Malignant meningiomas are rare and can exhibit aggressive behavior.
Observation:
- A 55-year-old man presented with a frontal mass lesion.
- Histological examination revealed pleomorphic tumor cells with necrosis and mitotic figures, showing a focal meningothelial pattern.
- Unique eosinophilic inclusion bodies were observed within tumor cells and intercellular spaces.
Findings:
- Electron microscopy showed tumor cells with minimal adherence, wide intercellular spaces, and branching cytoplasmic processes.
- The features suggested a malignant variant of arachnoid trabecular cell meningioma.
- The novel inclusion bodies were composed of fine granular material without a surrounding microvillar border.
Implications:
- This case presents a previously unreported type of inclusion body in meningiomas.
- The findings warrant further investigation into the significance and pathogenesis of these inclusions.
- Understanding these unique features may aid in the diagnosis and classification of rare meningioma subtypes.