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Case 377 - Discussion

Uploaded: 2009-11-09, Updated: 2009-11-09

 

Chordoma

CLINICAL FEATURES

  • A low-grade malignant tumor from the remnants of the notochord.

  • Confined to the spine, especially the proximal and distal portions, 50% within sacrococcygeal region.

  • 4% of malignant bone tumors.

  • 50-70 years of age, M:F=2:1.

RADIOLOGIC FINDINGS

  • Commonly as a lytic bone lesion that tends to push into surrounding soft tissues, causing expansion of bone.

GROSS FINDINGS

  • Soft, lobulated, grayish, glistening and translucent tumor.

MICROSCOPIC FINDINGS

  • Lobulated lesion divided by thin fibrous septa. Tumor cells are arranged in strands and cords in a blue mucinous background.
  • The tumor cells have small, round, uniform nuclei and abundant cytoplasm, which usually contains vacuoles, giving rise to physaliferous cells. Some tumors have sheets of tumor cells with eosinophilic cytoplasm, producing an epithelioid appearance.
  • Some cells show markedly pleomorphic, and the nuclei are enlarged and hyperchromatic.
  • Mitotic activity is generally low.
IMMUNOPHENOTYPE
  • Positive for epithelial markers keratin and EMA, and less consistently with S-100 protein.

ELECTRON MICROSCOPY

  • Shows some epithelial features as desmosomes, tonofilaments, and intracytoplasmic lumens with microvilli.

DIFFERENTIAL DIAGNOSES

  • Metastatic carcinoma with intracytoplasmic mucin:  more atypical, S100-.
  • Myxoid liposarcomas: chicken-wire capillary proliferation, cytokeratin-.
  • Myxoid chondrosarcoma (chordoid sarcoma): mostly in soft tissues, rarely in bone, S100+, cytokeratin-.

TREATMENT AND PROGNOSIS

  • Indolent tumor, mostly local progression, distant metastases in 20-30% of cases and usually involve the lungs and, less commonly, other bones and visceral organs.

REFERENCES: AFIP, tumor of the bone and joints, series 4