Pathology of Chordoma
Chordoma is a slow growing malignant bone tumour arising from the notochord remnants.
The tumour causes local destruction of the bone and may extend into the
surrounding soft tissue.
1) 50% arise from sacrococcygeal area
2) 35% in the spheno-occipital area (base of skull).
3) 15% cervico- thoraco-lumbar (mobile) spine.
Symptoms depend on the location and are usually present for a long time.
Sacrococcygeal chordoma may present as a anterior mass and rarely as a posterior mass.
A portion of the sacrum may be destroyed.
Retroperitoneal space is involved by direct extension of the tumour.
The enlarged tumour may compress the spinal cord, and may displace or surround the urinary bladder and large bowel.
The tumour may directly invade into the skin.
The patient always complains of pain and often present with constipation and urinary incontinence.
Spheno-occipital chordoma may present as nasal, paranasal or nasopharyngeal mass and the cranial nerves may also be involved.
Pituitary gland may be destroyed by the tumour.
Rarely, the tumour may appear as a tumour of cerebellopontine angle and acute pontocerebellar hemorrhage may occur.
The tumour usually occurs between 55 and 65 years.
Spheno-occipital tumours may occur in children. Over 60% cases occur in men.
Chondroid chordomas are more
common in women.
Soft, blue gray, lobulated tumour with gelationous appearance.
Focal areas of hemorrhage and areas of cystic degeneration may be present.
Tumour in the soft tissue appear to be encapsulated.
Chordoma appears as midline mass with areas of bony destruction.
An accompanying soft tissue lesion is also identified.
There are focal areas of calcification.
Chordoma at the base of the skull shows destructive, sclerotic lesion of
FNAB is a simple, rapid and cost effective method.
Chordoma has characteristic cytological features and a correct preoperative diagnosis is possible.
The aspirate shows large cells with pale stained vacuolated cytoplasm and ovoid nuclei. Some smaller uniform tumour cells are also present.
The cells are present in a myxoid backround.
The tumour is composed of lobules separated by fibrous tissue.
The tumour cells are arranged in cords, columns or trabeculae.
The tumour cells are set in a basophilic to metachromatic mucinous or myxoid stroma.
There are two types of cell - small, uniform, non vacuolated cells with ovoid nuclei and larger cells with mutivacuolated or bubble like cytoplasm and vesicular nuclei.
These large cells are known as "Physaliphorous cells" (Greek word for bubble or drop) and are diagnostic of chordomas.
Occasional mitotic figures may be identified. Some cellular pleomorphism
may be present which is of no prognostic significance.
The physaliphorous cells are PAS positive.
The matrix is alcian blue and mucicarmine positive.
The tumour cells are
positive for cytokeratins, epithelial membrane antigen (EMA), S100
protein and are rarely positive for CEA .
Chondroid chordoma- Shows prominent chondroid differentiation. Has a better prognosis.
Commonly located in the spheno-occipital region. Some authors consider these tumours to be chondrosarcoma. EMA and CEA positivity is less common in this variant.
Dedifferentiated chordoma- Highly malignant biphasic tumour composed of areas of high grade sarcoma and areas of typical chordoma. Indicates poor prognosis.
Differential diagnosis: Myxoid Tumours of Soft Tissue
Epithelial markers are negative. There are no fibrous bands
of the base of the skull: a clinicopathologic study of 200 cases with
emphasis on its distinction from chordoma.Am
J Surg Pathol. 1999
Epithelial markers are negative.
Metastatic carcinoma (Example- Signet ring carcinoma, renal cell carcinoma): Lobulated growth pattern is absent.
Epithelial markers are positive like chordoma. S100 protein is negative in metastatic carcinoma.
Giant notochordal rest - These are benign remnants of notochord tissue and
there is no bony destruction.
Rarely, distant metastasis may occur (lungs, liver, bone , lymph node).
Metastatic tumour in the skin may simulate a sweat gland tumour.
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