Peripheral nerve sheath tumours

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Peripheral nerve sheath tumours, abbreviated PNSTs, are common in neuropathology and occasionally show-up elsewhere. A very common PNST is the schwannoma.

Classification

A classification:[1]

Specific diagnoses

Schwannoma

Main article: Schwannoma

Perineurioma

General

  • Benign tumour derived from perineurial cells.

Variant:

  • Reticular perineurioma.[2]

Microscopic

Features:[3]

  • Perineural epithelioid cells.
    • Abundant pale, fluffy appearing cytoplasm.

Note:

  • May be intraneural.[3]

DDx:

Images:

IHC

Features:[4][5]

  • S100 -ve.
  • EMA +ve.
  • CD34 ~65% +ve.[4]

Traumatic neuroma

General

  • Consequence of trauma - diagnosis requires history of trauma.
    • May mimic a cancer recurrence at the site of a surgery.[6]

Microscopic

Features:[7][6]

  • +/-Nerve - that was injured.
  • Grouping of disordered nerve fibre bundles in fibrous tissue (collagen) - key feature.
  • +/-Myxoid change.
  • +/-Axonal swellings (ovoid pink/purple blobs).

DDx:

Images:

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SOFT TISSUE LESION, RIGHT WRIST, EXCISION:
- TRAUMATIC NEUROMA.
- BENIGN FIBROADIPOSE TISSUE.

Micro

The sections show disordered nerve fibre bundles in fibrous tissue.

Palisaded encapsulated neuroma

  • Abbreviated PEN.
  • AKA palisaded and encapsulated neuroma.

General

  • Flesh-colour papule - classically on the face.[9]
  • Isolated finding - not associated with a systemic disease or malignancy.[10]
  • Superficial skin.[11]

Microscopic

Features:[9]

  • Encapsulated dermal spindle cell lesion.
    • Fasciular arrangement.
    • Neural-type spindle cells:
      1. Not vacuolated.
      2. Nuclei have pointy ends.
  • Intralesional clefts.
    • Useful to differentiate from schwannoma.

DDx:

  • Schwannoma:[9]
    • No intralesional clefts.
    • More variability in the cellularity.
    • May be deep.

Other considerations:

  • Leiomyoma - cytoplasm not vacuolated, nuclei more elliptical.

Images:

IHC

Features:[10]

  • S100 +ve.
  • EMA +ve (capsule of lesion).

Neurofibroma

Main article: Neurofibroma

Includes discussion of plexiform neurofibroma.

Neurothekeoma

  • AKA myxoma of the nerve sheath, AKA nerve sheath myxoma.

General

  • Rare.
  • Female > male.

Microscopic

Features:[12]

  • Superficial dermal lesion:
    • Usu. lobulated or micronodular architecture - key feature.
      • +/-Focal sheeting.
    • Spindle/epithelioid morphology with pale eosinophilic cytoplasm - key feature.
    • +/-Inflammation around lesion.
    • +/-Surrounded by collagen.

Notes:

  • No atypia.
  • Mitoses rare/none.
  • Often poorly circumscribed.

Subtypes:[13]

  • Cellular.
  • Myxoid.
  • Intermediate.

DDx:

Images:

IHC

Features:[12]

  • NKI/C3 (AKA NKI-C3) +ve.
  • NSE +/-ve.

Others:[15]

  • Vimentin +ve.
  • CD10 +ve.
  • Microphthalmia transcription factor +ve.
  • PGP9.5 +ve.

Exclusionary:

  • S100 -ve.
    • Exclude other peripheral nerve sheath tumours. (???)

Malignant peripheral nerve sheath tumour

Main article: Malignant peripheral nerve sheath tumour

Malignant triton tumour

  • Abbreviated MTT.
  • AKA malignant peripheral nerve sheath tumor with rhabdomyosarcomatous differentiation.[16]

General

  • Rare.
  • Considered to be a variant of MPNST.
  • Prognosis worse that conventional MPNST.[16]
    • Five year survival ~14%.[17]
  • Diagnosis may require clinical information, i.e. individual has a history of neurofibromatosis type 1 (NF1).

Note:

  • A handful of benign triton tumours are reported; these are considered neuromuscular hamartomas.[18]

Microscopic

Features - Woodruff criteria - all three required:[16]

  1. (a) Tumour arise from a peripheral nerve or (b) individual has NF1 or (c) lesion a metastasis arising in the context of (a) or (b).
  2. Schwann cell tumour characteristics.
  3. Rhabdomyoblasts.
    • Eccentric nucleus.
    • Moderate amount of eosinophilic cytoplasm.
    • +/-Cross-striations.

DDx:

IHC

Features:

  • S100 +ve/-ve -- usu. focal if positive.[16]
  • Leu-7 +ve/-ve.
  • Myelin basic protein +ve/-ve.

Rhabdomyoblastic differentiation:[16]

  • Desmin.
  • Actin.
  • Myogenin.

EM

Morton neuroma

General

  • Benign foot condition.
  • Uncommon.
  • Usu. interdigital nerves.

Etiology:

  • Indirect nerve trauma.

Clinical:[19]

  • Foot pain.

Microscopic

Features:[19]

  • Extensive fibrosis around and within the nerve.
  • Digital artery:

DDx:

Images:

See also

References

  1. ↑ Wippold FJ, Lubner M, Perrin RJ, Lämmle M, Perry A (October 2007). "Neuropathology for the neuroradiologist: Antoni A and Antoni B tissue patterns". AJNR Am J Neuroradiol 28 (9): 1633–8. doi:10.3174/ajnr.A0682. PMID 17893219. http://www.ajnr.org/cgi/reprint/28/9/1633.
  2. ↑ Graadt van Roggen, JF.; McMenamin, ME.; Belchis, DA.; Nielsen, GP.; Rosenberg, AE.; Fletcher, CD. (Apr 2001). "Reticular perineurioma: a distinctive variant of soft tissue perineurioma.". Am J Surg Pathol 25 (4): 485-93. PMID 11257623.
  3. ↑ 3.0 3.1 3.2 Mills, Stacey E; Carter, Darryl; Greenson, Joel K; Reuter, Victor E; Stoler, Mark H (2009). Sternberg's Diagnostic Surgical Pathology (5th ed.). Lippincott Williams & Wilkins. pp. 424. ISBN 978-0781779425.
  4. ↑ 4.0 4.1 Hornick, JL.; Fletcher, CD. (Jul 2005). "Soft tissue perineurioma: clinicopathologic analysis of 81 cases including those with atypical histologic features.". Am J Surg Pathol 29 (7): 845-58. PMID 15958848.
  5. ↑ Tsang, WY.; Chan, JK.; Chow, LT.; Tse, CC. (Aug 1992). "Perineurioma: an uncommon soft tissue neoplasm distinct from localized hypertrophic neuropathy and neurofibroma.". Am J Surg Pathol 16 (8): 756-63. PMID 1497116.
  6. ↑ 6.0 6.1 6.2 Li, Q.; Gao, EL.; Yang, YL.; Hu, HY.; Hu, XQ. (2012). "Traumatic neuroma in a patient with breast cancer after mastectomy: a case report and review of the literature.". World J Surg Oncol 10: 35. doi:10.1186/1477-7819-10-35. PMID 22330690.
  7. ↑ Tadrous, Paul.J. Diagnostic Criteria Handbook in Histopathology: A Surgical Pathology Vade Mecum (1st ed.). Wiley. pp. 317. ISBN 978-0470519035.
  8. ↑ Kwon, JH.; Ryu, SW.; Kang, YN.. "Traumatic neuroma around the celiac trunk after gastrectomy mimicking a nodal metastasis: a case report.". Korean J Radiol 8 (3): 242-5. PMC 2627419. PMID 17554193. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2627419/.
  9. ↑ 9.0 9.1 9.2 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 536. ISBN 978-0443066542.
  10. ↑ 10.0 10.1 10.2 Newman, MD.; Milgraum, S. (2008). "Palisaded encapsulated neuroma (PEN): an often misdiagnosed neural tumor.". Dermatol Online J 14 (7): 12. PMID 18718196.
  11. ↑ S. Sade. 8 September 2011.
  12. ↑ 12.0 12.1 Hornick JL, Fletcher CD (March 2007). "Cellular neurothekeoma: detailed characterization in a series of 133 cases". Am. J. Surg. Pathol. 31 (3): 329–40. doi:10.1097/01.pas.0000213360.03133.89. PMID 17325474.
  13. ↑ Wang AR, May D, Bourne P, Scott G (November 1999). "PGP9.5: a marker for cellular neurothekeoma". Am. J. Surg. Pathol. 23 (11): 1401–7. PMID 10555009.
  14. ↑ URL: http://surgpathcriteria.stanford.edu/softfib/angiomatoid_fibrous_histiocytoma/. Accessed on: 11 May 2011.
  15. ↑ Fetsch JF, Laskin WB, Hallman JR, Lupton GP, Miettinen M (July 2007). "Neurothekeoma: an analysis of 178 tumors with detailed immunohistochemical data and long-term patient follow-up information". Am. J. Surg. Pathol. 31 (7): 1103–14. doi:10.1097/PAS.0b013e31802d96af. PMID 17592278.
  16. ↑ 16.0 16.1 16.2 16.3 16.4 16.5 Stasik, CJ.; Tawfik, O. (Dec 2006). "Malignant peripheral nerve sheath tumor with rhabdomyosarcomatous differentiation (malignant triton tumor).". Arch Pathol Lab Med 130 (12): 1878-81. doi:10.1043/1543-2165(2006)130[1878:MPNSTW]2.0.CO;2. PMID 17149968.
  17. ↑ McConnell, YJ.; Giacomantonio, CA. (Jan 2012). "Malignant triton tumors-complete surgical resection and adjuvant radiotherapy associated with improved survival.". J Surg Oncol. doi:10.1002/jso.23042. PMID 22253011.
  18. ↑ Castro, DE.; Raghuram, K.; Phillips, CD. (Apr 2005). "Benign triton tumor of the trigeminal nerve.". AJNR Am J Neuroradiol 26 (4): 967-9. PMID 15814954.
  19. ↑ 19.0 19.1 Mills, Stacey E; Carter, Darryl; Greenson, Joel K; Oberman, Harold A; Reuter, Victor E (2004). Sternberg's Diagnostic Surgical Pathology (4th ed.). Lippincott Williams & Wilkins. pp. 243. ISBN 978-0781740517.
  20. ↑ URL: http://www.sciencedirect.com/science/article/pii/S1027811711000863. Accessed on: 27 December 2012.
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