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Diagnosis: low grade Chondrosarcoma of the humeral head.
- Histologic grade: 1/3.
- Maximum tumor dimension: 10.0 cm.
- Mitotic rate: 0-1/10HPF |
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Sections of the
tumor show multiple lobules of immature cartilage varying in size
and shape. The neoplastic chondrocytes reveal mild pleomorphism with enlarged hyperchromatic nuclei
and frequent binucleation. The mitotic count is 0-1 per 10 hpf.
The tumor infiltrates into the marrow spaces and the bony
trabeculae, and the tumor permeates cortical bone into the soft
tissue in the medial inferior side. No tumor
necrosis or area of dedifferentiation is noted. |
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Chondrosarcoma |
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Clinical Futures |
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Third most common primary malignant bone tumor (myeloma,
osteosarcoma);
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Adulthood and old age;
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Pain, most common presenting symptom;
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Most common sites: pelvic, shoulder
girdles, upper ends
of femur and humor, >2/3 ( osteosarcoma most often
around the knee);
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Involve diaphysis and metaphysis, rarely epiphysis;
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Imaging studies commonly show calcification/minialilzation;
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Secondary chondrosarcoma: 25% of cases, malignant
transformation from preexisting enchondroma or osteochondroma;
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Gross Findings |
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Lobulated, light/gray blue or white masses with solid or
sticky mucoid matrix;
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Matrix may undergo liquefaction, producing cysts full of
liquid;
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Calcification, chalky white deposits;
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Necrosis.
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Microscopic Findings |
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Lobules of various sizes with hyaline/myxoid cartilage matrix;
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Calcification and reactive bone formation may be present;
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Malignant chondrocytes in lacunae;
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Permeation and distruction of the cortical bone;
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Permeation of the medullary bone.
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Grading: cellularity, matrix (solid or myxoid), cytology,
and relationship to the bone (permeative or not)
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Grade 1 (low-grade)
Very similar to enchondroma. However, the
cellularity is higher, and there is mild
cellular pleomorphism. The nuclei are small
but often show open chromatin pattern and
small nucleoli. Binucleated cells are
frequent. Mitoses are very rare. Grade 1
chondrosarcomas are locally aggressive and
prone to recurrences, but usually do not
metastasize.
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Grade 2 (low-grade)
The cellularity is higher than in Grade 1
tumors. Characteristic findings are moderate
cellular pleomorphism, plump nuclei,
frequent bi-nucleated cells, and occasional
bizarre cells. Mitoses are rare. Foci of
myxoid change may be seen. Unlike Grade 1
tumors, about 10% to 15% of Grade 2
chondrosarcomas produce metastases.
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Grade 3 (high-grade)
Characteristic findings are high
cellularity, marked cellular pleomorphism,
high N/C ratio, many bizarre cells and
frequent mitoses (more than 1 per hpf).
These are high grade tumors with significant metastatic
potential
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Subtypes |
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Dedifferentiated (high grade), 6-10%
- rare type of high grade chondrosarcoma which arises from
a low grade chondrosarcoma;
- a high-grade spindle-cell sarcoma coexists with a
lower-grade chondroid tumour;
- histologically there will be areas c/w MFH, osteosarcoma,
or fibrosarcoma;
- high risk for metatastasis, only 5% of patients will
survive more than 5 years;
- Myxoid type, 5%
- Msenchymal type, 2%
- Clear cell (intermediate grade), 2%
- rare, slow growing, locally recurrent tumor easily
confused w/ chondroblastoma but malignant;
- tumor is especially rare in a child or adolescent;
- may invade epiphysis;
- most common in proximal femur (over 50%) followed
by proximal humerus;
- microscopically, sheets of cartilaginous cells in a
lobular arrangement are mixed with scattered giant cells;
- this radiolucent lesion is often misdiagnosed and
undertreated;
- Atypical enchondroma (juxtacortical chondroma), 2%
- histologic exam of a low grade chondrosarcoma may show
nodular cartilage tissue with mostly isomorphic tumor cells;
- tissue samples show cellularity than is seen w/
enchondroma;
- differentiating between this malignant tumor growth and
an enchondroma can be extremely difficult;
- an aysmptomatic, well circumscribed calcified lesion
which has not changed in size is most consistent w/ an enchondroma;
- more peripherally located lesions are also more likely to
represent an enchondroma;
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Differential Diagnosis |
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Enchondromas:
usually have well defined borders with
no evidence of invasion. Quite often you will see nodules of
enchondroma surrounded by the bone marrow and reactive bone
trabeculae. That should not be mistaken for invasion. On the
contrary, malignant nodules of chondrosarcoma infiltrate between
the lamellar bone obliterating the marrow. Separation of the
nodules by fibrous bands would be another feature highly
suggestive of malignancy.
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Chondroblastic osteosarcoma: affects children, sheets
of spindle cells with the formation of lace -like osteoid.
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Immunohistochemistry Straining |
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Cytogenetics |
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Extraskeletal myxoid chondrosarcomas
have been demonstrated to
be caused by chimeric genes generated by translocations. The
translocation t(9;22)(q22;q12) results in fusion of the CSMF (NR4A3)
and EWS genes, creating a chimeric EWS/CSMF oncogene. The
translocation t(9;17)(q22;q11) results in fusion of the CSMF and
RBP56 genes, creating a chimeric RBP56/CSMF gene in cases of
extraskeletal myxoid chondrosarcomas.
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Treatment and Prognosis |
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Low-grade (Grades 1 and 2) tumors are locally aggressive and prone
to recurrences, but their metastatic potential is low. Recurrent
tumors may show an increase in grade. High-grade (Grade 3) tumors
metastasize to the lungs, skin, and soft tissues.
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Reference |
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Hasegawa T, Seki K, Yang P, et al:
Differentiation and proliferative activity in benign and
malignant cartilage tumors of bone. Hum Pathol 26:838,
1995
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Oshiro Y, Chaturvedi V, Hayden D, Nazeer T,
Johnson M, Johnston DA, Ordonez NG, Ayala AG, Czerniak B.
Altered p53 is associated with aggressive behavior of
chondrosarcoma: a long-term follow-up study. Cancer
1998;83(11):2324-2334
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Nawa G, Ueda T, Mori S, et al: Prognostic
significance of Ki-67 (Mib1) proliferation index and P53
over-expression in chondrosarcomas. Int J Cancer 69:86,
1996
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AFIP, series 4
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