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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.
Site and
presentation:
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.
Age:
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.
Gross:
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.
X-ray
findings:
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
the clivus.
FNAB:
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.
Microscopic features:
Image Link1
;
Image Link2
;
Image Link3
;
Image Link4. 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.
Special stains:
The
physaliphorous cells are PAS positive. The matrix is alcian blue and
mucicarmine positive.
Immunohistochemistry:
The tumour cells
are positive for cytokeratins, epithelial membrane antigen (EMA), S100
protein and vimentin and are rarely positive for CEA .
Microscopic variants of chordoma:
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.
[Chondroid
chordoma--a variant of chordoma. A morphologic and immunohistochemical
study.Am
J Clin Pathol. 1994
Jan;101(1):36-41 Immunohistochemical
distinction of classic and chondroid chordomas.Mod
Pathol. 1991
Sep;4(5):661-6.
Chondroid chordoma. A hyalinized
chordoma without cartilaginous differentiation.
Am J Clin Pathol.
1995 Mar;103(3):271-9.
Intraoperative squash and touch
cytology of chondroid chordoma of the skull base. Report of a case with
immunocytochemical and immunohistochemical studies.Acta
Cytol. 1997
May-Jun;41(3):913-8]
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
Chondrosarcoma:
Epithelial markers are negative.There are no fibrous bands separating
lobules. Chondrosarcoma
of the base of the skull: a clinicopathologic study of 200 cases with
emphasis on its distinction from chordoma.Am
J Surg Pathol. 1999 Nov;23(11):1370-8.
Myxopapillary ependymoma:
Epithelial
markers are negative
Metastatic carcinoma (eg 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.
Chordoma has a high rate of recurrence. The patient may have a long
disease free interval
(almost 10 years) following radical resection of the tumour with excision
margins free of tumour.
Rarely, distant metastasis may occur (lungs, liver, bone , lymph node).
Metastatic tumour in the skin may simulate a sweat gland tumour.
Parachordoma:
Located in the
soft tissue of the lower extremities and trunk. The tumour consists of
epithelioid cells, glomoid cells and spindle cells and are cytokeratin
8/18 , S100 protein and sometimes EMA positive. CEA is negative.
Parachordoma is not distinguishable from axial chordoma
using immunohistochemistry.Pathol
Int. 2004 May;54(5):364-70.
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