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

Perineurioma

General

  • Benign tumour derived from perineurial cells (intraneural or soft tissue).
    • ICD-O 9571/0
    • WHO grade I
  • Rarely malignant soft tissue perineurioma.

Variant:

  • Reticular perineurioma.[2]

Macroscopy

  • Intraneural perineurioma: segmental tubular enlargement of the nerve.
  • Soft tissue perineurioma: Well circumscribed, but not encapsulated.

Microscopic

Features:[3]

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

Note:

  • May be intraneural.[3]
    • Typical pseudo-onion bulbs.
    • Long considered hypertrophic neuropathy.
    • Rare (less than 1% of all nerve sheath tumours).

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.
  • AKA solitary circumscribed neuroma.

General

  • Flesh-colour papule - classically on the face.[10]
  • Isolated finding - not associated with a systemic disease or malignancy.[11]
  • Superficial skin papule.[12]
  • It is considered hyperplastic rather than neoplastic. [13]

Microscopic

Features:[10]

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

DDx:

  • Schwannoma:[10]
    • No intralesional clefts.
    • More variability in the cellularity.
    • May be deep.

Other considerations:

  • Leiomyoma - cytoplasm not vacuolated, nuclei more elliptical.

Images:

Palisading/encapcuslated neuroma Palisading/encapcuslated neuroma
Palisading/encapsulated (Reed’s) neuroma. A. A dermal nodule shows an attenuated capsule (black arrows) about a fasciculated spindle cell lesion with artefactual clefts (green arrows). B. The bland spindled nuclei, amid clear cytoplasm with thin eosinophilic wisps, are often wavy (black arrows), with pointed ends (green arrows); leiomyomas have blunt ended nuclei and more eosinophilic cytoplasm. These benign neoplasms, unlike neurofibromas, lack an association with neurofibromatosis.

IHC

Features:[11]

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

Neurofibroma

Includes discussion of plexiform neurofibroma.

Neurothekeoma

  • AKA myxoma of the nerve sheath, AKA nerve sheath myxoma.
  • There is growing evidence that neurothekomas and dermal nerve sheath myxomas are distinct entities.[14]

General

  • Rare.
  • Female > male.

Microscopic

Features:[15]

  • 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:[16]

  • Cellular.
  • Myxoid.
  • Intermediate.

DDx:

Images:

IHC

Features:[15]

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

Others:[18]

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

Exclusionary:

  • S100 -ve.
    • Exclude other peripheral nerve sheath tumours. (???)
    • Myxoid variant +ve. [citation needed]

Malignant peripheral nerve sheath tumour

Malignant triton tumour

  • Abbreviated MTT.
  • AKA malignant peripheral nerve sheath tumor with rhabdomyosarcomatous differentiation.[19]

General

  • Rare.
  • Considered to be a variant of MPNST.
  • Prognosis worse that conventional MPNST.[19]
    • Five year survival ~14%.[20]
  • 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.[21]

Microscopic

Features - Woodruff criteria - all three required:[19]

  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.[19]
  • Leu-7 +ve/-ve.
  • Myelin basic protein +ve/-ve.

Rhabdomyoblastic differentiation:[19]

  • Desmin.
  • Actin.
  • Myogenin.

EM

Morton neuroma

AKA plantar interdigital neuroma.[22]

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. //www.ncbi.nlm.nih.gov/pmc/articles/PMC2627419/.
  9. Kitcat, M.; Hunter, JE.; Malata, CM. (2009). "Sciatic neuroma presenting forty years after above-knee amputation.". Open Orthop J 3: 125-7. doi:10.2174/1874325000903010125. PMID 20224738.
  10. 10.0 10.1 10.2 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 536. ISBN 978-0443066542.
  11. 11.0 11.1 11.2 Newman, MD.; Milgraum, S. (2008). "Palisaded encapsulated neuroma (PEN): an often misdiagnosed neural tumor.". Dermatol Online J 14 (7): 12. PMID 18718196.
  12. S. Sade. 8 September 2011.
  13. Rosai & Ackermann, Surgical Pathology, 10th ed. p183
  14. Sheth, S.; Li, X.; Binder, S.; Dry, SM. (Mar 2011). "Differential gene expression profiles of neurothekeomas and nerve sheath myxomas by microarray analysis.". Mod Pathol 24 (3): 343-54. doi:10.1038/modpathol.2010.203. PMID 21297585.
  15. 15.0 15.1 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.
  16. 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.
  17. URL: http://surgpathcriteria.stanford.edu/softfib/angiomatoid_fibrous_histiocytoma/. Accessed on: 11 May 2011.
  18. 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.
  19. 19.0 19.1 19.2 19.3 19.4 19.5 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.
  20. 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.
  21. 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.
  22. Makki, D.; Haddad, BZ.; Mahmood, Z.; Shahid, MS.; Pathak, S.; Garnham, I. (Sep 2012). "Efficacy of corticosteroid injection versus size of plantar interdigital neuroma.". Foot Ankle Int 33 (9): 722-6. doi:DOI: 10.3113/FAI.2012.0722. PMID 22995258.