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Flashcards in Bones & Joints Deck (253)
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31

Conventional intramedullary osteosarcoma: Presentation (2).

Weeks to months of mild, intermittent pain.

Presentation with a pathologic fracture is rare.

32

Conventional intramedullary osteosarcoma: Laboratory finding.

Elevated serum alkaline phosphatase.

33

Conventional intramedullary osteosarcoma: Radiography (2).

Lytic, sclerotic, or both.

Metaphyseal.

34

Conventional intramedullary osteosarcoma: Radiography of periosteal reaction (3).

Codman's triangle.

Sunburst.

Onion-skin appearance.

35

Conventional intramedullary osteosarcoma: Gross pathology (2).

Mass originating in the medulla has growth through the cortex and into the soft tissue.

May contain osteoblastic, chondroid, or fibroblastic (soft and fleshy) areas.

36

Conventional intramedullary osteosarcoma: Basic histology (2).

Malignant osteoblasts producing osteoid.

Sarcomatous stroma that may exhibit heterologous differentiation.

37

Conventional intramedullary osteosarcoma: Normalization.

Once incorporated into the osteoid, the tumor cells become smaller.

38

Conventional intramedullary osteosarcoma: Chondroid and fibroblastic types.

In both of these tumors, osteoid may be inapparent, requiring a careful search.

39

Conventional intramedullary osteosarcoma: Giant-cell-rich type.

Rich in osteoclast-like giant cells.

40

Conventional intramedullary osteosarcoma: Small-cell variant (2).

Tumor cells resemble those of other tumors of small round blue cells.

Identified by IHC or by the demonstration of osteoid.

41

Conventional intramedullary osteosarcoma: Histology after preoperative radiation (2).

Acellular osteoid, acellular chondroid tissue.

Fibrosis.

42

Conventional intramedullary osteosarcoma: Indicators of effective preoperative chemotherapy (2).

More than 90% of the tumor is necrotic.

The cells have gone from predominantly aneuploid to predominantly diploid.

43

Conventional intramedullary osteosarcoma: Immunohistochemistry.

SATB2 is a transcription factor (nuclear stain) of osteoblasts.

44

Conventional intramedullary osteosarcoma: Mutated genes.

Hereditary tumors: RB.

Non-hereditary: TP53 in some.

45

Conventional intramedullary osteosarcoma vs. low-grade conventional chondrosarcoma.

The chondroid areas of osteosarcoma are usually high-grade.

46

Conventional intramedullary osteosarcoma vs. dedifferentiated chondrosarcoma.

The chondroid areas of osteosarcoma are usually high-grade.

The chondroid areas of dedifferentiated chondrosarcoma are usually low-grade.

47

Conventional intramedullary osteosarcoma vs. clear-cell chondrosarcoma.

Clear-cell chondrosarcoma:

- Clear cells.
- Epiphyseal location.

48

Most common malignant tumors in adolescents (4).

Leukemia.

Brain tumors.

Lymphoma.

Osteosarcoma.

49

Telangiectatic osteosarcoma: Main age group.

Second decade.

50

Telangiectatic osteosarcoma: Sites.

Metaphyseal:

- Distal femur.
- Proximal tibia.
- Proximal humerus.

51

Telangiectatic osteosarcoma: Presentation.

More likely than conventional osteosarcoma to cause pathologic fracture.

52

Telangiectatic osteosarcoma: Radiography (2).

Purely lytic.

Periosteal reaction like that of conventional osteosarcoma.

53

Telangiectatic osteosarcoma: Gross pathology.

Hemorrhagic mass that may be multicystic and necrotic.

54

Telangiectatic osteosarcoma: Histology (4).

Cystic spaces.

Septa of cysts contain
- Malignant mononuclear and multinucleate stromal cells.
- Osteoclast-like giant cells.

Tumor osteoid is lacelike and may be hard to find.

55

Telangiectatic osteosarcoma: Immunohistochemistry.

Positive: SATB2.

56

Telangiectatic osteosarcoma vs. aneurysmal bone cyst.

Aneurysmal bone cyst: Stromal cells usually lack atypia and atypical mitotic figures.

57

Telangiectatic osteosarcoma: Association.

Most common type of osteosarcoma to arise from longstanding Paget's disease.

58

Telangiectatic osteosarcoma: Prognosis.

Better than that of conventional osteosarcoma.

59

Parosteal osteosarcoma: Synonym.

Juxtacortical osteosarcoma.

60

Parosteal osteosarcoma: Sites.

Metaphyseal:

- Distal femur.
- Proximal tibia.