Schwannoma of the brachial plexus

Case contributed by Dr Shu Su

Presentation

History withheld.

Patient Data

Age: 57
Gender: Female
Modality: MRI

1. A rounded component within the canal, extending from the C4/5 level upward behind the C4 vertebral body, to the right of the cervical cord causes dramatic compression of the cervical cord which is displaced posterolaterally towards the left and has high T2 signal. The mass appears intradural, connected to the foraminal component along the C5 nerve root sheath.

2. The component of the mass within the foramen results in bony remodelling and displacement of the right vertebral artery anteriorly.

3. The large lateral component deep to sternocleidomastoid is located posterolateral to the carotid sheath.

The remainder of the study is unremarkable, with no other masses evident. The cervical cord above and below the compressing lesion is unremarkable also.

Report from Department of Radiology, Royal Melbourne Hospital.  

Modality: Annotated image

Annotated image of key findings. 

Case Discussion

Tumours appear as focal or multifocal thickening of a section of the brachial plexus. Tumours are usually low intensity on T1-weighted imaging, high intensity on T2-weighted imaging and typically enhance with contrast, although with variable characteristics. Of the primary tumours, three are neurogenic tumours formed directly from the brachial plexus – benign schwannomas, benign neurofibromas and malignant peripheral nerve sheath tumour (MPNST) 1.  

Schwannomas typically causes spherical distension of the nerve; the nerve appears to enter and leave the tumour eccentrically, displacing nerve fascicles. There is usually no peritumoural oedema. The intensity of schwannomas is similar  to muscle on T1-weighted images,and markedly hyperintense on T2-weighted images. The tumour often displays a fascicular sign i.e. "salt and pepper" appearance of multiple ring-like structures with peripheral hyperintensity in T2, although this sign but can be present in any neurogenic tumour. However, in 15% of schwannomas, there may instead be a target sign i.e. hyperintense rim of myxoid tissue with central hypointense area due to more fibrocollagenous tissue on T2-weighted imaging. Finally, when contrast is injected, schwannomas usually display inhomogenous and diffuse enhancement 1-3.

Case courtesy of A/Prof Pramit Phal.

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Case Information

rID: 37484
Case created: 10th Jun 2015
Last edited: 28th Sep 2015
Inclusion in quiz mode: Included

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