|
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 |
|
|
|
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 |