Chondrosarcoma is a malignant tumor that produces
cartilage matrix. Primary chondrosarcoma is very uncommon, arises centrally
in the bone, and is found in children. Secondary chondrosarcoma arises
from benign cartilage defects such as osteochondroma or enchondroma. Chondrosarcoma
can also be classified as intramedullary, which generally arise
from enchondromas, and surface which arise from osteochondromas.
Chondrosarcoma occurs in the fifth or sixth decades and has a male to
female ratio of 1.5 to 1. It is most common in the femur, humerus, ribs
and on the surface of the pelvis. Patients with Ollier's disease (multiple
enchondromatosis) or Maffucci's syndrome (multiple enchondromas and hemangiomas)
are at much higher risk of chondrosarcoma than the normal population and
often present in the third and fourth decade.
The presentation of chondrosarcoma depends on the
grade of the tumor. A high-grade, fast growing tumor can present with
excruciating pain. A low grade, more indolent tumor is more likely to
present as an older patient complaining of hip pain and swelling. Pelvic
tumors present with urinary frequency or obstruction or may masquerade
as "groin muscle pulls".
On plain radiographs, chondrosarcoma is a fusiform,
lucent defect with scalloping of the inner cortex and periosteal reaction.
Extension into the soft tissue may be present as well as punctate or stippled
calcification of the cartilage matrix. CT is helpful in defining the integrity
of the cortex and distribution of calcification. MRI is invaluable in
surgical planning as it demonstrates the intraosseus and soft tissue involvement
of the tumor. MRI is also helpful in evaluating possible malignant degeneration
of osteochondromas by allowing accurate measurements of the cartilage
cap which should be less than 2 cm thick.
On gross examination, chondrosarcoma is a grayish-white,
lobulated mass. It may have focal calcification, mucoid I degeneration,
or necrosis.Histologically, chondrosarcoma is differentiated from benign
cartilage growths by enlarged plump nuclei, multiple cells per lacunae,
binucleated cells, and hyperchromic nuclear pleomorphism. Chondrosarcoma
is graded from 1 (low) to 3 (high). Low grade chondrosarcoma is very close
in appearance to enchondromas and osteochondromas and has occasional binucleated
cells. High grade chondrosarcomas have increased cellularity, atypia and
mitoses. There is an inverse relationship between histologic grade and
prognosis with higher grades having a worse prognosis and early metastases.
There are three additional types of chondrosarcoma.
Mesenchymal chondrosarcoma is a rare variant with a bimorphic histologic
picture of low grade cartilaginous cells and hypercellular small, uniform,
and undifferentiated cells that resemble Ewing's sarcoma. Mesenchymal
chondrosarcoma has a predilection for the spine, ribs and jaw and it presents
in the third decade. It is more common in females and can grow exceptionally
large. It is very likely to metastasize to lungs, Iymph nodes and other
bones. Clear cell chondrosarcoma
is a malignant cartilage tumor that may be the adult variant of chondroblastoma.
It is a rare, low-grade tumor with an improved prognosis over other chondrosarcomas.
Likechondroblastoma, it is found in the epiphysis of the femur and humerus.
Histologically, soft tissue invasion is rare. Clear cell chondrosarcoma
has clear cells with vacuolated cytoplasm. The cartilage matrix has significantly
calcified trabeculae and giant cells. Dedifferentiated chondrosarcoma
is the most malignant form of chondrosarcoma. This tumor is a mix of low
grade chondrosarcoma and high grade spindle cell sarcoma where the spindle
cells are no longer identifiable as having a cartilage origin. The dedifferentiated
portion of the lesion may have histological features of malignant fibrous
histiocytoma, osteosarcoma, or undifferentiated sarcoma. This biphasic
quality is evident on x-ray with areas of endosteal scalloping and cortical
thickening are contrasted with areas of cortical destruction and soft
tissue invasion. Dedifferentiated chondrosarcoma has a 5 year survival
Treatment of chondrosarcoma is wide surgical excision.
There is a very limited role for chemotherapy or radiation. Biopsies must
be planned with future tumor excision in mind. Patients with adequately
resected low grade chondrosarcomas have an excellent survival rate. The
survival of patients with high grade tumors depends on the location, size
and stage of the tumor.
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Bulloughs, Peter, orthopedic Pathologv (third edition), Times Mirror International
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Huvos, Andrews, Bone Tumors: Diagnosis, Treatment and Prognosis, W.B.
Saunders, Co., 1991.