30 year-old female with right sciatic neuropathy clinically. No change in imaging findings over two years.

What is the most likely diagnosis?

  • Answer:

3)  Intraneural Perineurioma of right sciatic nerve

  • Findings:
  1. Fusiform enlargement of a segment of the right sciatic nerve, hyper intense on T2W images
  2. According the patient’s history, age and no progression over two years, imaging findings are mostly suggestive for perineurioma.
  3. CIDP and amyloidosis are in ddx, they mostly present with multifocal neuropathies.
  • Discussion:
  1. Intraneural perineurioma is a neoplasm of perineurial cells, corresponding to WHO grade I.
  2. It is a benign hypertrophic (non onion bulb) peripheral nerve tumor that presents insidiously in young people and is motor predominant with mild sensory involvement. It is most often a mono neuropathy, but a plexopathy can occur.
  3. The sciatic nerve or its branches is most commonly affected followed by brachial plexus, radial nerve and ulnar nerve .
  4. Magnetic resonance imaging demonstrates fusiform nerve enlargement ranging greatly in length, but typically longer than 10 cm ,T1 iso intensity , T2 hyper intensity and contrast enhancement .
  5. Diagnosis of this condition requires clinical suspicion, imaging, targeted fascicular biopsy of the lesion and expertise of nerve pathologists. As these tumors are static or slowly progressive, remain confined to their original distribution and have low morbidity, they probably should not be resected routinely.


  • Restrepo CE, Amrami KK, Howe BM, Dyck PJ, Mauermann ML, Spinner RJ. The almost-invisible perineurioma. Neurosurg Focus. 2015 Sep;39(3):E13.
  • Mauermann ML, Amrami KK, Kuntz NL, Spinner RJ, Dyck PJ, Bosch EP, Engelstad J, Felmlee JP, Dyck PJ. Longitudinal study of intraneural perineurioma–a benign, focal hypertrophic neuropathy of youth. Brain. 2009 Aug;132(Pt 8):2265-76.
  • Nacey NC, Almira Suarez MI, Mandell JW, Anderson MW, Gaskin CM. Intraneural perineurioma of the sciatic nerve: an under-recognized nerve neoplasm with characteristic MRI findings. Skeletal Radiol. 2014 Mar;43(3):375-9.
  • Dahlin LB, Nennesmo I, Besjakov J, Ferencz I, Andersson GS, Backman C. Case report: Intraneural perineurioma of the sciatic nerve in an adolescent – strategies for revealing the diagnosis. Clin Case Rep. 2016 Jul 6;4(8):777-81.


Courtesy of Parham Pezeshk,MD, Assistant Professor, Division of Musculoskeletal Imaging Department of Radiology, University of Texas Southwestern Medical Center,Dallas,TX