Peripheral nerve sheath tumor of sciatic nerve

Case contributed by Assoc Prof Frank Gaillard


Mass behind knee, slowly growing over 6 years. Normal nerve conduction studies.

Patient Data

Age: 45
Gender: Male

An ovoid 2.5 x 2.8 x 4.3 cm lesion intimately related to the tibial nerve at the level of the popliteal fossa is demonstrated. This is isointense to muscle on T1 imaging, high however heterogeneous T2 signal intensity with heterogeneous vivid contrast enhancement. The lesion abuts however is separate from the popliteal artery. The lesion is clearly separate from the adjacent musculature.

No joint effusion.The menisci, cruciate and collateral ligaments are intact. There is mild high signal within the distal popliteus tendon at its insertion, consistent with mild enthesopathy. No posterolateral corner abnormality. Mild insertional enthesopathy involving the quadriceps tendon, with small patellar spur. Articular surfaces are within normal limits.


Well-defined ovoid lesion arising from the tibial nerve in the popliteal fossa consistent with a peripheral nerve sheath tumor.

Case Discussion

The patient continues to be followed as is essentially asymptomatic. 

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Case information

rID: 29453
Published: 7th Jul 2014
Last edited: 14th Aug 2019
Inclusion in quiz mode: Included

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