Related Experiment Video
Updated: May 7, 2026
Lateral Molar Approach-Driven Transoral Endoscopic Procedure for Benign Infratemporal Fossa Tumor Resection
Published on: August 15, 2025
A case of intraosseous microcystic meningioma without a mass lesion
Shinya Ichimura1, Koichi Hara, Reiko Shimokawa
1Department of Neurosurgery, Saiseikai Yokohamashi Tobu Hospital.
Abstract:
Both intraosseous and microcystic meningiomas are rare tumor types. We report the case of a 66-year-old woman with intraosseous microcystic meningioma without a mass lesion. She presented with a rare intraosseous microcystic meningioma manifesting as pain. Radiological examination revealed an osteolytic lesion in the right parietal bone. Magnetic resonance (MR) images showed iso- to hypointensity on T1-weighted images and hyperintensity on T2-weighted images corresponding to the lesion. T1-weighted MR imaging with gadolinium enhancement better defined the marginal area. The inner table of the skull was disrupted prominently, and both sides of the outer table were eroded. There was fluid leakage during surgery but no obvious tumor mass. Histological examination revealed microcystic meningioma in the inner part of the defective bone. A macroscopic lesion was not found, because most of the tumor comprised microcysts, and their contents leaked out during the surgical procedure. Intraosseous microcystic meningioma may be considered as one of the differential diagnoses when the intraosseous tumor in the skull has fluid leakage and does not have a mass lesion during the surgery.
Insights
This case report details a rare intraosseous microcystic meningioma presenting as bone pain without a visible mass. Diagnosis was confirmed via histology after surgical fluid leakage, highlighting its unique presentation.
Area of Science:
- Neurosurgery
- Oncology
- Radiology
Background:
- Intraosseous meningiomas are rare tumors arising from ectopic meningothelial cells within bone.
- Microcystic meningiomas are a rare subtype characterized by small cystic spaces.
- This report focuses on the unusual presentation of an intraosseous microcystic meningioma.
Observation:
- A 66-year-old woman presented with pain attributed to an osteolytic lesion in the right parietal bone.
- Radiological imaging, including MRI with gadolinium, revealed an eroded skull lesion with indistinct margins.
- Intraoperative findings included significant fluid leakage but no macroscopic tumor mass.
Findings:
- Histological examination confirmed the presence of microcystic meningioma within the defective bone.
- The absence of a macroscopic lesion was due to the microcystic nature of the tumor and intraoperative fluid loss.
- The tumor exhibited iso- to hypointensity on T1-weighted and hyperintensity on T2-weighted MRI sequences.
Implications:
- Intraosseous microcystic meningioma should be considered in the differential diagnosis of skull osteolytic lesions, especially those with intraoperative fluid leakage and no apparent mass.
- This case expands the understanding of meningioma presentations and diagnostic challenges.
- Accurate preoperative diagnosis and surgical planning are crucial for managing such rare intraosseous tumors.
Related Concept Videos
01:26Brain Abscess l: Introduction
01:19Cranial and Spinal Meninges
Cranial Meninges
These meningeal layers cover the cranium. The dura mater is the outermost layer of cranial meninges. It is a thick and durable membrane of dense...