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Solitary fibrous tumor of the dura

Solitary fibrous tumor of the dura (SFT-dura) is a rare extra-axial dural mass typically presenting in middle-aged patients (mean age 47-56 years) with nonspecific symptoms such as headache that depend on tumor size and location.

Key Images

Look For First

Extra-axial well-circumscribed dural mass with vivid heterogeneous contrast enhancement
Low to isointense T2 signal ('yin-yang' appearance with areas of low and high signal intensity)
Prominent surface flow voids without spoke-wheel pattern, often larger than meningiomas

Key Image Findings

On CT: well-circumscribed isodense to hyperdense mass arising from dura, may show calcifications and bone erosion, found at supratentorial convexity, falx, tentorium, or posterior fossa
On MRI T1: intermediate signal similar to adjacent brain parenchyma
On MRI T2: iso- to hypointense signal, which is the best diagnostic clue for distinguishing from meningiomas; characteristic 'yin-yang' appearance with separate areas of low and high signal intensity
On MRI T1 C+: vivid diffuse heterogeneous enhancement of low T2 signal components with prominent surface flow voids (not spoke-wheel pattern) and uncommon dural tail
Restricted diffusion on DWI/ADC with elevated rCBV on MR perfusion
MRS shows elevated lipid, lactate, and myo-inositol
On DSA: prominent tumor blush with variable feeding vessels from both meningeal and pial sources
Histologically composed of spindle cells with thick collagen bands, staghorn vessels, NAB2-STAT6 fusion gene, and characteristic immunophenotype (CD34+, vimentin+, STAT6+ nuclear translocation)

Differential Diagnosis

Meningioma (far more common): distinguish by T2 iso-to-hyperintensity, presence of calcification, MRS alanine and glutamate peaks, and spoke-wheel flow void pattern
Schwannoma: characteristic locations and typically iso-to-hyperintense T2 signal
Primary dural lymphoma: may also have low T2 signal but different clinical context and immunophenotype
Dural metastases: clinical history and multiplicity may help distinguish
Lymphoma, Erdheim-Chester disease, and melanocytic lesions: also present with low T2 signal requiring correlation with histology

Discussion

Solitary fibrous tumors of the dura are histologically identical to hemangiopericytomas, which are now classified as WHO grade 2-3 SFTs rather than separate entities (2016 WHO classification)

Clinical presentation is nonspecific and identical to other dural masses, with headache being the most common symptom

Complete surgical resection is usually curative, but recurrence rates are highly variable (reported up to 50%), with incomplete resection or recurrence requiring adjuvant radiotherapy

Rare paraneoplastic syndromes include non-islet cell tumor hypoglycemia (NICTH) from IGF-2 secretion and acromegaly

The key imaging distinguishing feature is low T2 signal intensity, which is much less common in the more frequent meningioma

Unlike meningiomas, SFTs of the dura are often larger, more vividly enhancing, have prominent surface flow voids, and lack intralesional calcification

Reporting Pearls

Describe the mass as an extra-axial dural lesion with intermediate T1 signal, low-to-isointense T2 signal (specifically noting 'yin-yang' heterogeneity if present), vivid heterogeneous enhancement with prominent surface flow voids, and lack of intralesional calcification; emphasize that while appearance overlaps with meningioma (which should remain the primary diagnosis given frequency), the combination of low T2 signal and prominent enhancement without calcification favors solitary fibrous tumor.

Pitfalls

Overcalling meningioma due to similar extra-axial presentation with enhancement and dural tail; remember SFTs are often larger, lack calcification, and have lower T2 signal
Missing the characteristic 'yin-yang' T2 appearance as a diagnostic clue specific to SFT
Attributing all low T2 signal dural lesions to SFT when lymphoma, Erdheim-Chester disease, and melanocytic lesions can also present with hypointensity on T2; correlation with immunohistochemistry and clinical context is essential
Confusing prominent surface flow voids of SFT with the spoke-wheel pattern typical of meningiomas; SFT shows peripheral flow voids without central radial pattern

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