Target sign (peripheral nerve sheath tumor)
Target sign
(peripheral nerve sheath tumor) • L3 nerve root neuroma - Ganzer Fall bei Radiopaedia
Target sign
(peripheral nerve sheath tumor) • Peripheral nerve sheath tumor of the sciatic nerve - Ganzer Fall bei Radiopaedia
Target sign
(peripheral nerve sheath tumor) • Peripheral nerve sheath tumor of S1 nerve root - Ganzer Fall bei Radiopaedia
The target sign of peripheral nerve sheath tumor (PNST) is a lesional pattern of T2 signal on MRI consisting of a central area of low intensity surrounded by a T2 hyperintense rim. It is most commonly associated with localized neurofibroma, having been shown to correspond histopathologically with a dense central area of collagenous stroma surrounded by myxomatous tissue .
Unfortunately, the target sign is neither sensitive nor specific for either neurofibroma or for benign tumor:
- one study including 22 benign PNSTs showed a target sign in only 21%
- a similar "target sign" has also been observed in schwannoma, albeit less commonly. It is believed that the histopathologic correlate may be the alternating Antoni A and B zones, the latter of which consist of tumor cells surrounded by edema-like fluid
- a "target sign" has also been observed in malignant peripheral nerve sheath tumor
