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Parachordoma

Definition

  • Neoplasm of small to large, frequently vacuolated cells set in a hyalinized matrix, similar in appearance to a chordoma but arising away from the craniospinal axis

Alternate/Historical Names

  • Chordoma periphericum
  • Chordoid tumor (some cases)
  • Chordoid sarcoma (some cases)

Diagnostic Criteria

  • Cords and nests of cells
    • May form whorls
    • May form pseudoglands
    • Hyalinized stroma
  • Predominantly large cells with eosinophilic cytoplasm
    • Occasional physalliferous cells
      • Very large cells with vacuolated cytoplasm
    • Merge with spindled or small round cells
    • Vesicular to pyknotic nuclei
  • Positive for S100 and CK 8/18 (Cam5.2)
  • No mitotic figures, necrosis or vascular invasion
  • Circumscribed, not encapsulated
  • Non-axial location
    • Mestastatic chordoma must be ruled out

Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting:: February 3, 2007

Supplemental studies

Immunohistology

S100 Positive
CD8/18, CAM5.2 Positive
EMA Positive
CK34BE12 Negative
CKAE1 Negative
CK7, CK20 Negative
CEA Negative
Type IV Collagen Surrounds nests
CD57 Positive
Smooth muscle actin Negative
Muscle specific actin Negative
Desmin Negative
CD34 Negative
CD31 Negative

Genetic analysis

  • Various clonal abnormalities reported, none consistent

Differential Diagnosis

Chordoma Parachordoma
Occurs on craniospinal axis Non-axial location
CK7 and 34BE12 positive CK7 and 34BE12 negative
No collagen IV around nests Collagen IV around nests
  • Both are S100 and CK8/18 positive.
  • Mestastic chordoma must be ruled out.
  • Ectopic chordoma is controversial and requires immunohistology features above.

    •  

    Myxoid Chondrosarcoma Parachordoma
    Predominantly long chains of cells Predominantly nests and cords of cells
    Uniformly small cells Small and large cells
    EMA and keratin rarely positive EMA and keratin uniformly positive
    S100 infrequent, patchy S100 consistent, uniform
    Stroma purely myxoid Stroma myxoid and hyalinized
    Alcian blue hyaluronidase resistant Alcian blue hyaluronidase sensitive
    t(9;22) in 75% of cases t(9;22) not seen

     

    Chondroid Syringoma of Skin Parachordoma
    Actin positive component Actin negative
    No large vacuolated cells Large vacuolated cells at least focally
    Both are S100 and keratin positive

     

    Chondroid Lipoma Parachordoma
    Contains mature fat No fat integral to lesion
    EMA negative EMA positive
    Keratin variable Keratin positive
    Both are S100 positive

     

    Myoepithelioma Parachordoma
    Actin positive Actin negative
    May form ducts No true ducts
    Both are keratin and S100 positive.

    Clinical

    • Age 4-86, usually adolescents and young adults
    • Usually adjacent to tendon, synovium or bone
      • Occasionally cutaneous
      • Rarely osseous
    • Non-axial location required
      • Most on extremities
    • Non-destructive recurrences 25%
    • Two questionable cases with metastases reported
      • One keratin negative
      • One positive for keratin 34BE12

    Grading / Staging / Report

    • Grading and staging are not applicable
    • Managerial category Ib (Recurrences do occur but are not destructive; never metastasizes)
      • (Two cases with unusual phenotypes are reported with metastases)

    Lists

    Keratin positive soft tissue tumors (frequent and strong)

    Bibliography

    • Kempson RL, Fletcher CDM, Evans HL, Henrickson MR, Sibley RS. Tumors of the Soft Tissues, Atlas of Tumor Pathology, AFIP Third Series, Fascicle 30, 2001
    • Fletcher CDM, Unni KK, Mertens F. Pathology and Genetics of Tumours of Soft Tissue and Bone, World Health Organization Classification of Tumours 2002
    • Weiss SW, Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors, 4th edition, 2001
    • Fisher C. Parachordoma exists--but what is it? Adv Anat Pathol. 2000 May;7(3):141-8.
    • Folpe AL, Agoff SN, Willis J, Weiss SW. Parachordoma is immunohistochemically and cytogenetically distinct from axial chordoma and extraskeletal myxoid chondrosarcoma. Am J Surg Pathol. 1999 Sep;23(9):1059-67.
    • Fisher C, Miettinen M. Parachordoma: a clinicopathologic and immunohistochemical study of four cases of an unusual soft tissue neoplasm. Ann Diagn Pathol. 1997 Oct;1(1):3-10.
    • Dabska M. Parachordoma: a new clinicopathologic entity. Cancer. 1977 Oct;40(4):1586-92.
    • Nielsen GP, Mangham DC, Grimer RJ, Rosenberg AE. Chordoma periphericum: a case report. Am J Surg Pathol. 2001 Feb;25(2):263-7.
    • Imlay SP, Argenyi ZB, Stone MS, McCollough ML, Henghold WB. Cutaneous parachordoma. A light microscopic and immunohistochemical report of two cases and review of the literature. J Cutan Pathol. 1998 May;25(5):279-84. Review.
    • Tihy F, Scott P, Russo P, Champagne M, Tabet JC, Lemieux N. Cytogenetic analysis of a parachordoma. Cancer Genet Cytogenet. 1998 Aug;105(1):14-9.
    • Limon J, Babinska M, Denis A, Rys J, Niezabitowski A. Parachordoma: a rare sarcoma with clonal chromosomal changes. Cancer Genet Cytogenet. 1998 Apr 1;102(1):78-80.
    • Sangueza OP, White CR Jr. Parachordoma. Am J Dermatopathol. 1994 Apr;16(2):185-8.
    • Shin HJ, Mackay B, Ichinose H, Ayala AG, Romsdahl MM. Parachordoma. Ultrastruct Pathol. 1994 Jan-Apr;18(1-2):249-56.
    • Ishida T, Oda H, Oka T, Imamura T, Machinami R. Parachordoma: an ultrastructural and immunohistochemical study. Virchows Arch A Pathol Anat Histopathol. 1993;422(3):239-45.
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