History: A 27-year-old woman presents with progressive vertigo, ataxia, and headaches.
A head MRI scan was performed. Axial and sagittal T1-weighted, axial and coronal T1-weighted postcontrast, axial T2-weighted, and axial T2-weighted fluid-attenuated inversion-recovery (FLAIR) MR images are shown below.
There is an avidly enhancing lobular mass with multiple internal cystic components centered in the posterior fossa measuring up to 4.3 cm. The mass is associated with the dura as it extends across the left tentorium cerebelli into the supratentorial region. Additionally, there are cerebrospinal fluid clefts, which suggests that the lesion is extra-axial. The mass does not exhibit restricted diffusion. There is mass effect on the fourth ventricle, which is nearly completely affected. There is obstructive hydrocephalus of the third and lateral ventricles with evidence of transependymal CSF resorption. There is vasogenic edema in the bilateral cerebellar hemispheres and vermis.
Solitary fibrous tumor of dura (meningeal hemangiopericytoma)
Diagnosis: Solitary fibrous tumor of dura (meningeal hemangiopericytoma)
Solitary fibrous tumor of dura
Solitary fibrous tumors (SFT) were originally described as primary neoplasms of the visceral pleura, well-encapsulated spindle-cell tumors that only became symptomatic by mass effect. However, they were found to have a mesenchymal origin and were seen in numerous extrapleural sites, including within the central nervous system (intraspinal, intracranial, and along cranial nerves).
Hemangiopericytomas (HPC) were described as a distinct entity, classified as a subtype of meningiomas, thought to arise from smooth muscle pericytes of dural capillaries. However, like solitary fibrous tumors, they were found to arise from fibroblasts and share the same molecular genetics as SFTs. In fact, SFTs and HPCs were combined into the same entity in the 2016 World Health Organization (WHO) classification of central nervous system tumors (with hemangiopericytomas now being an obsolete term). SFT/HPC is a highly cellular and vascular tumor (WHO grades I to III) that often has systemic metastases at diagnosis (liver, lung, and bones). Classic histologic features include a “staghorn” branching stromal vascular pattern.
They account for less than 1% of intracranial tumors and are most often found in younger adults (ages 30 to 45) with a slightly higher prevalence in males.
Clinical presentation 临床表现
Symptoms are secondary to mass effect and include headaches, seizures, and focal neurologic dysfunction.
Although imaging findings may distinguish an SFT/HPC from a meningioma, pathology is necessary to confirm the diagnosis, ideally by immunohistochemistry identifying NAB2-STAT6 fusion.
Imaging findings 影像表现
SFT/HPCs are solitary, lobulated, heterogeneous masses.
They are highly vascular and avidly enhancing.
They can be infratentorial and/or supratentorial in location.
Most common locations include the occipital region and may involve the falx, tentorium, or dural sinuses.
They are extra-axial but may have a narrow base of dural attachment.
On CT, there may be erosion of adjacent bone but no calcifications or hyperostosis.
On MRI, they will be isointense to gray matter on T1- and T2-weighted imaging, but mass effect on adjacent brain will display T2/FLAIR hyperintensity.
On MR spectroscopy, there is often a myo-inositol peak.
Meningiomas are usually smoother, have a broader dural tail, cause hyperostosis, and have a central spoke-wheel vascular supply.
Treatment and prognosis 治疗及预后
They require total surgical resection with preoperative catheter embolization.
Adjuvant radiotherapy helps reduce the rate of recurrence.
They have a high risk of local recurrence (50% to 90%) and metastases many years later.
Patients have a median survival of three to six years without metastases and two years with metastases.