Parachordoma

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Parachordoma is a very rare paraspinal tumour that is similar to chordoma.[1]

General

  • Super rare - only approximately 30 cases reported.[2]
  • Slow growing.[1]

Gross

Features:[1]

  • Deep soft tissue lesion.
  • Firm.
  • Well-circumscribed.
  • Most often thigh or arm.[2]

Microscopic

Features:[2]

  • Multivacuolated cells (physaliferous cell-like) - key feature.
    • May be rare.
  • "Large" rounded eosinophilic cells - important.
  • Variable matrix:
    • Myxoid.
    • Dense appearing hyaline - cartilage-like.
  • Small cells (spindled and rounded) - common.

DDx:

Stains

  • Alcian blue +ve (matrix).[2]

IHC

Features:[2]

  • CK 8/18 +ve.
  • EMA +ve.
  • S-100 +ve.
  • Vimentin +ve.

Note:

  • Other keratins negative.

See also

References

  1. 1.0 1.1 1.2 Fisher C (May 2000). "Parachordoma exists--but what is it?". Adv Anat Pathol 7 (3): 141–8. PMID 10809219.
  2. 2.0 2.1 2.2 2.3 2.4 Folpe, AL.; Agoff, SN.; Willis, J.; Weiss, SW. (Sep 1999). "Parachordoma is immunohistochemically and cytogenetically distinct from axial chordoma and extraskeletal myxoid chondrosarcoma.". Am J Surg Pathol 23 (9): 1059-67. PMID 10478665.