Schwannoma

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Schwannoma is a relatively common peripheral nerve sheath tumour.

Schwannoma
Diagnosis in short

Schwannoma showing Antoni A and Antoni B areas. HPS stain.

LM

Antoni A areas (cellular, fibrillary, polar, elongated), Antoni B area (pauci-cellular, loose microcystic tissue), Verocay bodies (paucinuclear area surrounded by nuclei), hyaline thickened blood vessels, thick capsule.

+/-peripheral lymphoid cuff (esp. GI tract)
Subtypes conventional schwannoma, cellular schwannoma, plexiform schwannoma, melanotic schwannoma
LM DDx meningioma, leiomyoma, GIST, intranodal palisaded myofibroblastoma, MPNST
IHC S-100 +ve, EMA -ve, CD34 +ve
Site soft tissue - peripheral nerve sheath tumours

Syndromes neurofibromatosis type 2, Carney complex (psammomatous melanotic schwannoma)

Prevalence common
Prognosis good
Clin. DDx meningioma - esp. at CP angle

General

Microscopic

Features:[1]

  • Antoni A:
    • Cellular.
    • 'Fibrillary, polar, elongated'.
  • Antoni B:
    • Pauci-cellular.
    • Loose microcystic tissue.
  • Verocay bodies - paucinuclear area surrounded by nuclei - diagnostic feature.
  • Hyaline thickened blood vessels.
  • Thick capsule.
  • In the GI tract: classically have a peripheral lymphoid cuff.[2]
  • +/-Hemosiderin deposition within tumour.

Notes:

  • Tumour does not smear well.[3]
  • Antoni A: may look somewhat like scattered matchsticks.

DDx:

Images

www:

Schwannoma subtypes

There are four:[5]

  1. Conventional schwannoma.
  2. Cellular schwannoma.
  3. Plexiform schwannoma.
  4. Melanotic schwannoma.

Conventional schwannoma

  • Most common.

Cellular schwannoma

Images:

Plexiform schwannoma

  • May mimic MPNST if cellular - esp. in childhood.

Images:

Melanotic schwannoma

  • May be confused with melanoma.
  • Psammomatous form (psammomatous melanotic schwannoma) associated with a heritable disorder (Carney complex).

Note:

  • Carney complex:[5]
    • Cutaneous lentigines.
    • Myxomas (skin (subcutaneous), subcutanous, heart).
    • Endocrine neoplasms.

Images:

IHC

Features:[6]

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. Levy AD, Quiles AM, Miettinen M, Sobin LH (March 2005). "Gastrointestinal schwannomas: CT features with clinicopathologic correlation". AJR Am J Roentgenol 184 (3): 797–802. PMID 15728600. http://www.ajronline.org/cgi/content/full/184/3/797.
  3. MUN. 24 November 2010.
  4. Chan, PT.; Tripathi, S.; Low, SE.; Robinson, LQ. (2007). "Case report--ancient schwannoma of the scrotum.". BMC Urol 7: 1. doi:10.1186/1471-2490-7-1. PMID 17244372.
  5. 5.0 5.1 Kurtkaya-Yapicier O, Scheithauer B, Woodruff JM (July 2003). "The pathobiologic spectrum of Schwannomas". Histol. Histopathol. 18 (3): 925–34. PMID 12792904.
  6. Hirose T, Tani T, Shimada T, Ishizawa K, Shimada S, Sano T (April 2003). "Immunohistochemical demonstration of EMA/Glut1-positive perineurial cells and CD34-positive fibroblastic cells in peripheral nerve sheath tumors". Mod. Pathol. 16 (4): 293–8. doi:10.1097/01.MP.0000062654.83617.B7. PMID 12692193. http://www.nature.com/modpathol/journal/v16/n4/full/3880761a.html.
  7. Nonaka D, Chiriboga L, Rubin BP (September 2008). "Sox10: a pan-schwannian and melanocytic marker". Am. J. Surg. Pathol. 32 (9): 1291–8. doi:10.1097/PAS.0b013e3181658c14. PMID 18636017.
  8. Rushing, EJ.; Bouffard, JP.; McCall, S.; Olsen, C.; Mena, H.; Sandberg, GD.; Thompson, LD. (Jun 2009). "Primary extracranial meningiomas: an analysis of 146 cases.". Head Neck Pathol 3 (2): 116-30. doi:10.1007/s12105-009-0118-1. PMID 19644540.