Spinal schwannoma is the most common intradural extramedullary tumor arising from dorsal nerve roots, constituting 25-30% of all spinal tumors. It consists of benign neoplastic proliferation of Schwann cells. Histologically, it contains Antoni A (compact, cellular) and Antoni B (loose, myxoid) areas — imaging reflection is characteristic T2 hyperintensity and heterogeneous enhancement. Lumbar region is the most common location (40%), followed equally by cervical (30%) and thoracic (30%) — different from meningioma's thoracic predilection. Gender predilection is not prominent (different from meningioma's female predominance). When extending through the neural foramen, it creates a 'dumbbell' tumor with intradural and extradural components (15-30%) — this morphology is nearly pathognomonic for schwannoma. NF2 shows multiple spinal schwannomas. On MRI, marked T2 hyperintensity, heterogeneous enhancement, target sign, and dumbbell morphology are diagnostic clues. Neural foramen widening on CT (bone remodeling from slow growth) is characteristic.
Age Range
25-70
Peak Age
45
Gender
Equal
Prevalence
Uncommon
Spinal schwannoma originates from the Schwann cell sheath of dorsal spinal nerve roots. Schwann cells form the myelin sheath insulating peripheral nervous system axons. Monoklonal proliferation creates an encapsulated tumor — displacing but generally not invading the nerve root, allowing nerve preservation during surgical enucleation. Histologically, Antoni A areas contain compact spindle cells with Verocay bodies — appearing as solid enhancing component. Antoni B areas contain loose myxoid stroma with high water content causing long T2 relaxation and marked T2 hyperintensity. Target sign is the T2 combination of central low signal (Antoni A — fibrous/cellular) and peripheral high signal (Antoni B — myxoid). Cystic degeneration develops from expansion and coalescence of Antoni B areas. Dumbbell morphology results from tumor extending through the neural foramen from intradural to extradural (paravertebral) space. Foramen widening reflects chronic pressure erosion (remodeling) from slow-growing tumor — not aggressive bone destruction.
Hourglass-shaped mass with intradural and extradural (paravertebral) components passing through the neural foramen is a nearly pathognomonic morphological finding for schwannoma. The tumor narrows within the foramen. Seen in 15-30% of schwannomas and critical for surgical planning.
Marked T2 hyperintense signal is the most characteristic MRI finding of schwannoma. Myxoid stroma of Antoni B areas produces bright signal with long T2. Target sign (central hypointense + peripheral hyperintense) may be seen in large lesions. Cystic degeneration areas are very hyperintense with water signal.
Report Sentence
Intradural extramedullary mass showing marked T2 hyperintense signal, consistent with schwannoma.
Heterogeneous enhancement on contrast-enhanced MRI is typical of schwannoma. Solid components (Antoni A) enhance intensely while cystic degeneration areas (Antoni B) do not — creating 'ring-like' or heterogeneous pattern. Distinctly different from meningioma's homogeneous enhancement.
Report Sentence
Intradural extramedullary mass showing heterogeneous enhancement with cystic degeneration areas, consistent with schwannoma.
Neural foramen widening on CT reflects bone remodeling from schwannoma's slow growth. Smooth-bordered foramen widening indicates benign growth pattern — aggressive destruction suggests malignancy. Dumbbell morphology: intradural and extradural components connected through the foramen, hourglass configuration.
Report Sentence
Smooth-bordered neural foramen widening with dumbbell morphology mass extending intradural-extradurally on CT, consistent with schwannoma.
T1 signal hypointense to isointense relative to cord. Long T1 of myxoid stroma and cystic degeneration areas creates hypointensity. T1 hyperintense areas may be seen with hemorrhage (metHb).
Report Sentence
Intradural extramedullary mass hypointense to cord on T1.
CSF space (CSF cap sign) between mass and cord — confirms intradural extramedullary location. T2 hyperintense CSF surrounds the mass in a crescent shape. This finding is critical for differentiation from intramedullary masses.
Report Sentence
T2 hyperintense CSF space between mass and cord, supporting intradural extramedullary location.
Criteria
Classic two-component histology: Antoni A + Antoni B
Distinct Features
Most common type; typical T2 hyperintensity and heterogeneous enhancement; variable cystic degeneration; target sign may be seen; excellent prognosis
Criteria
Predominant Antoni A pattern (>80%), minimal Antoni B
Distinct Features
More solid and homogeneous appearance; T2 hyperintensity less prominent; more homogeneous enhancement — may be confused with meningioma; differentiation from MPNST may be difficult; low recurrence risk
Criteria
Multiple nerve involvement, plexiform growth pattern, associated with NF2 or schwannomatosis
Distinct Features
Multiple spinal schwannomas — all spinal levels may be affected; NF2 accompanied by bilateral vestibular schwannoma; schwannomatosis has multiple schwannomas without NF2; genetic counseling required
Distinguishing Feature
Meningioma shows T2 isointensity, homogeneous enhancement, dural tail, broad dural base — cystic degeneration rare. Schwannoma shows marked T2 hyperintensity, heterogeneous enhancement, cystic degeneration, and dumbbell morphology. Meningioma more common in thoracic region and women, schwannoma in lumbar region with equal gender.
Distinguishing Feature
Metastasis is usually associated with bone destruction, multiple lesions, and irregular margins. Schwannoma is encapsulated, solitary, well-defined, and does not cause bone destruction (foramen widening is smooth remodeling).
Distinguishing Feature
Neural foramen widening and dumbbell morphology on CT are typical of schwannoma but not seen in meningioma. Calcification (25%) is seen in meningioma on CT while calcification is rare in schwannoma.
Urgency
routineManagement
surgicalBiopsy
Not NeededFollow-up
12-monthSpinal schwannoma is benign and surgical resection is curative. Gross total resection minimizes recurrence risk (5%). Dumbbell morphology affects surgical planning — combined posterior and anterolateral approach may be needed. In NF2 patients, symptomatic lesions are prioritized. MPNST rarely develops from schwannoma but should be suspected with rapid growth, irregular margins, and high FDG uptake.
Spinal schwannoma is a benign tumor and surgical resection is curative. It slowly grows causing progressive radiculopathy and myelopathy. Dumbbell morphology affects surgical planning — anterior approach may be needed. Multiple schwannomas may be seen in NF2 and schwannomatosis should be differentiated. Recurrence rate is increased with subtotal resection.