Solitary fibrous tumours of the dura are rare, slow-growing benign tumours, often seen in adults, characterised by positive immunohistochemistry, intense homogeneous contrast enhancement, and absence of calcification/dural tail.
Description
A solitary fibrous tumour of the dura (SFTD) is a mesenchymal neoplasm arising from the dura mater. Although traditionally considered benign, a small subset can show aggressive behaviour. It is the intracranial counterpart of solitary fibrous tumours that occur in various other body sites.
Pathogenesis
The pathogenesis of SFTDs remains unclear. They are believed to originate from mesenchymal cells capable of fibroblastic differentiation. Some theories propose a reactive or inflammatory process, while others suggest a neoplastic origin.
Subtypes
There are no distinct subtypes of SFTD identified.
Epidemiology, Risk Factors & Associations
- Most commonly seen in adults, with a slight female predominance.
- No specific risk factors or associations have been identified for SFTD.
Clinical Features
The presentation of SFTD is typically non-specific and related to mass effect, with symptoms including headache, seizures, and focal neurological deficits.
Complications
- A small proportion of SFTDs can behave aggressively, with local recurrence and rarely, extracranial metastasis.
Pathological Features
Histopathology
- Macroscopic: These tumours are well-circumscribed and firm with a whorled, white-grey cut surface.
- Microscopic: Characterised by alternating hypercellular and hypocellular areas, with bland spindle cells set in a collagenous stroma.
Serology
There are no specific serological markers for SFTD.
Biochemistry
No specific biochemistry findings are associated with SFTD.
Immunohistochemistry
Positive staining for CD34, BCL-2 and STAT-6.
Radiological Features
General Features
- Extra-axial, dural-based mass, with a broad-based attachment to the dura.
- Characteristically shows intense homogeneous enhancement following contrast administration. Dural tail not usually seen.
- Calcifcations are rare.
CT
- Non-contrast: Iso- to hyperdense compared to brain parenchyma. Calcifications are rare.
- C+ Arterial and Venous: Shows intense homogeneous enhancement.
MRI
- T1: Iso- to hypointense to grey matter.
- T2: Variable intensity, can be hyper-, iso-, or hypointense to grey matter.
- FLAIR: Similar to T2.
- DWI/ADC: No restriction of diffusion.
- T1 Gad+: Intense, homogeneous enhancement.
US
- B-mode and Colour: Not typically used for intracranial tumours.
NM
- PET FDG: Not typically used for SFTD but if done, shows increased uptake.
Grading and Staging
There is no specific grading or staging system for SFTDs.
Diagnosis
The diagnosis of SFTD is primarily made by histopathological examination following surgical resection, with characteristic microscopic features and positive staining for CD34, BCL-2 and STAT-6 on immunohistochemistry.
Differential Diagnosis
- Meningioma: Most common mimic, but typically shows ‘dural tail’ sign, and often contains calcifications and may be less intensely enhancing. More common in older adults.
- Haemangiopericytoma: Tends to be more aggressive, with irregular shape and heterogenous enhancement.
Management
Surgical resection is the primary treatment for symptomatic or growing SFTDs. Regular follow-up with imaging is recommended due to the potential for recurrence, particularly if complete resection was not achieved.