schwannoma

A picture is
worth a thousand... differential diagnosis: lumbar cystic schwannoma. Marked peripheral ring-like enhancement with central area of low signal of the mass in T1-weighted postcontrast images. Sagittal plane.
www.eurorad.org • CC by-nc-sa-4.0
Schwannom am
Kleinhirnbrückenwinkel rechts (links im Bild) in der MRT T1KM axial.
Wikipedia • CC BY-SA 3.0
An unusual
case of latero-cervical swelling. Color-Doppler evaluation shows mild vascularity inside the lesion.
www.eurorad.org • CC by-nc-sa-4.0
An unusual
case of latero-cervical swelling. A hyperintense, encapsulated mass (arrowheads) occupies the right carotid space and lies between the common carotid artery and the jugular vein, displaced postero-laterally. Its connection with the vagus nerve may be seen (arrows).
www.eurorad.org • CC by-nc-sa-4.0
An unusual
case of latero-cervical swelling. A hyperintense, encapsulated mass (arrowheads) occupies the right carotid space and lies between the common carotid artery and the jugular vein, displaced postero-laterally.
www.eurorad.org • CC by-nc-sa-4.0
An unusual
case of latero-cervical swelling. Fat-saturated T1-weighted TSE sequences after administration of gadolinium-based contrast agent show heterogeneous enhancement of the mass (arrowheads).
www.eurorad.org • CC by-nc-sa-4.0
An unusual
case of latero-cervical swelling. Fat-saturated T1-weighted TSE sequences after administration of gadolinium-based contrast agent show heterogeneous enhancement of the mass (arrowheads).
www.eurorad.org • CC by-nc-sa-4.0
Ultrasound
diagnosis of lumbar spinal nerve root tumour. Ultrasound image shows a 5x4.5 cm size mixed heterogeneous well-defined lesion in the right paraspinal region. The lesion displaces the right psoas muscle (outlined by white arrows) anteromedially.
www.eurorad.org • CC by-nc-sa-4.0
Ultrasound
diagnosis of lumbar spinal nerve root tumour. Coronal plain CT image shows a well-defined homogeneous soft tissue density lesion in continuity with the nerve root. Absent right kidney is noted.
www.eurorad.org • CC by-nc-sa-4.0
Ultrasound
diagnosis of lumbar spinal nerve root tumour. Coronal T2 weighted MR image shows a well defined heterogeneously hyperintense lesion with peripheral hypointense rim arising from exiting nerve root at L3 vertebra.
www.eurorad.org • CC by-nc-sa-4.0
Ultrasound
diagnosis of lumbar spinal nerve root tumour. A well-defined soft tissue density lesion (white star) in right paraspinal region arises eccentrically from the exiting nerve root at L3 vertebra (white arrows). The lesion displaces the right psoas muscle (gray arrow) anteriorly.
www.eurorad.org • CC by-nc-sa-4.0
MRI imaging
of soft tissue tumours of the foot and ankle. Schwannoma. a Coronal T1W image demonstrating a well-defined homogeneously T1 isointense lesion with the split fat sign (arrows). b Coronal T2FS image of another schwannoma showing a homogeneously hyperintense lesion with a “ball on a string” sign denoting origin from the posterior tibial nerve (arrow). c The same lesion demonstrates avid enhancement on the post-contrast T1FS image
insightsimaging.springeropen.com • CC-by-4.0
Tumor and
tumorlike conditions of the pleura and juxtapleural region: review of imaging findings. Diagnosis: schwannoma. Technique: standard chest radiography, contrast-enhanced chest CT and 18FDG-PET CT. Description: A 55-year-old man with no significant medical history was referred for a chest radiograph because of a persistent cough. As an incidental finding, a sharp delineated mass (arrow) laterally in the right hemithorax was found on the postero-anterior chest radiograph (a). Coronal and axial CT images (b, c) in the mediastinal window setting reveal a small homogeneous lesion located intercostally between the 5th and 6th right ribs. The lesion shows high uptake on 18-F-FDG PET (d). Although the high uptake on PET may mislead to a malignant cause, histopathologic examination of the resected specimen confirmed the suggested diagnosis of a schwannoma
insightsimaging.springeropen.com • CC-by-4.0
Tumor and
tumorlike conditions of the pleura and juxtapleural region: review of imaging findings. Diagnosis: benign schwannoma with low mitotic activity. Technique: standard chest radiography, contrast-enhanced chest CT and MRI. Description: A 55-year-old man with respiratory distress was transferred to our hospital after drainage of a hemothorax. The antero-posterior chest radiograph (a) shows a large mass in the left lung with a perilesional rim of air (due to pneumothorax). On contrast-enhanced CT (b) the homogeneous hypointense mass is located paravertebral in the left lower lobe with vertebral scalloping (arrow on c). There are no intralesional calcifications or necrosis. Note also the adjacent consolidation due to atelectasis. On the axial T2 FS WI MR image (d), the lesion has a high signal intensity and is relatively enhancing after contrast administration (e). Based on imaging findings and the size of the lesion, a malignant nerve sheath tumor was suggested. Histopathologic examination of the resected mass, however, did not reveal signs of malignancy but showed an 11-cm large benign schwannoma with low mitotic activity. Genetic counseling for NF-1 was negative
insightsimaging.springeropen.com • CC-by-4.0
Partial
laryngectomy and reconstruction with rotation of the epiglottis in the treatment of a rare laryngeal schwannoma: a case report . Magnetic resonance imaging (MRI) showing a well-circumscribed, clearly outlined supraglottic tumor with regular edges and hyperintensity in T2-weighted images, causing significant obstruction of the laryngeal lumen
jmedicalcasereports.biomedcentral.com • CC-by-4.0
Ultrasound
diagnosis of lumbar spinal nerve root tumour. High resolution colour Doppler scan shows that the lesion is well defined, mildly heterogeneous and with internal vascularity.
www.eurorad.org • CC by-nc-sa-4.0
An unusual
case of latero-cervical swelling. B-mode evaluation shows a solid homogeneous mass (arrowheads) compressing the jugular vein (J). Continuity with the vagus nerve is hypothesized (arrows).
www.eurorad.org • CC by-nc-sa-4.0
Radiopaedia • CC-by-nc-sa 3.0 • de

Schwannomas, less commonly called neurinomas or neurilemmomas, are benign tumors of Schwann cell origin and are the most common tumor of peripheral nerves, including cranial nerves.

This article provides a general overview of schwannomas. For a discussion of schwannomas located at specific sites, please refer to the relevant articles listed below.

Epidemiology

Peak presentation is in the 5-6 decades. When they occur in patients with neurofibromatosis type 2 (NF2), schwannomas usually present by the 3 decade . There is no sex predilection.

Associations

Most schwannomas are solitary (90%)  and sporadic, however, there is an association with NF2 (abnormality of chromosome 22). Multiple schwannomas are characteristic of NF2. Approximately 18% of solitary schwannomas occur in patients with NF2 .

There is also schwannomatosis, which consists of multiple schwannomas without the concomitant involvement of cranial nerve VIII.

Clinical presentation

Presentation depends on the location of the tumor (see below) but generally, symptoms are due to local mass effect or dysfunction of the nerve they arise from.

Pathology

Macroscopic appearance

Schwannomas are benign encapsulated neoplasms of Schwann cells (WHO grade I). They arise eccentrically from their parent nerve, with the nerve fibers splayed along their surface (as distinct to neurofibromas which arise within the nerve).

Microscopic appearance

Conventional schwannomas are composed of spindle cells which demonstrate two growth patterns: Antoni type A and Antoni type B .

Antoni type A pattern: elongated cells are densely packed and arranged in fascicles. Palisades are sometimes seen; when prominent these form Verocay bodies.

Antoni type B pattern cells are less compact and are prone to cystic degeneration.

Variants

Schwannoma variants include :

  • ancient schwannoma
  • cellular schwannoma
    • predominantly composed of Antoni A tissue
    • no Verocay bodies
    • most commonly found in a paravertebral location, or trigeminal nerves (CN V)
  • melanotic schwannoma: dense melanin pigment
  • plexiform schwannoma
    • usually arise from skin or subcutaneous tissues
    • usually diagnosed at birth or childhood
    • usually sporadic, but rarely associated with NF2
    • should not be confused with plexiform neurofibromas
      • associated with NF1
      • may undergo malignant change
Locations

Radiographic features

General imaging features of schwannomas include:

  • well-circumscribed masses which displace adjacent structures without direct invasion
  • cystic and fatty degeneration is common
  • the larger a schwannoma, the more likely it is to show heterogeneity because of cystic degeneration or hemorrhage
  • hemorrhage occurs in 5% of cases
  • calcification is rare
CT

CT is not as sensitive or specific for the diagnosis of schwannoma as MRI but is often the first investigation obtained. It is particularly useful in assessing bony changes adjacent to the tumor.

Imaging features include:

  • low to intermediate attenuation
  • intense contrast enhancement
    • small tumors typically demonstrate homogeneous enhancement
    • larger tumors may show heterogeneous enhancement
  • adjacent bone remodeling with smooth corticated edges
MRI

Schwannomas have fairly predictable signal characteristics :

  • T1: isointense or hypointense
  • T1 C+ (Gd): intense enhancement
  • T2: heterogeneously hyperintense (Antoni A: relatively low, Antoni B: high)
    • cystic degenerative areas may be present, especially in larger tumors
  • T2*: larger tumors often have areas of hemosiderin

A number of signs can also be useful:

  • split-fat sign: thin peripheral rim of fat best seen on planes along long axis of the lesion in non-fat-suppressed sequences
  • target sign
    • peripheral high T2 signal
    • central low signal
    • rarely seen intracranially
  • fascicular sign: multiple small ring-like structures

Treatment and prognosis

Schwannomas are slow-growing lesions. Surgery is the treatment of choice. As schwannomas do not infiltrate the parent nerve, they can usually be separated from it. Recurrence is unusual, even after complete resection. They almost never undergo malignant change.

Siehe auch:
und weiter:
Assoziationen und Differentialdiagnosen zu Schwannom:
Paragangliom
 
www.eurorad.org • CC by-nc-sa-4.0
spinal
paraganglioma
wjso.biomedcentral.com • CC-by-2.0
spinale
Schwannome
www.eurorad.org • CC by-nc-sa-4.0
benigner
peripherer Nervenscheidentumor
www.eurorad.org • CC by-nc-sa-4.0
intraspinales
Meningeom
Wikipedia • CC BY-SA 3.0
Vestibularisschwannom
 
Wikipedia • CC BY-SA 4.0
Schwannom der
Cauda equina
wjso.biomedcentral.com • CC-by-4.0
spinale
Metastasen
Wikipedia • CC BY-SA 3.0
spinales
Ependymom des Filum terminale
www.eurorad.org • CC by-nc-sa-4.0
intradurale
extramedulläre Tumoren
www.eurorad.org • CC by-nc-sa-4.0
Neoplasien
der Cauda equina
www.eurorad.org • CC by-nc-sa-4.0
Unterscheidung
Schwannom Neurofibrom
www.eurorad.org • CC by-nc-sa-4.0