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AP reviewer > Bones & Joints > Flashcards

Bones & Joints Flashcards

1
Q

Osteoma: Presentation.

A

May be asymptomatic.

May cause symptoms if involving sinuses or orbits.

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2
Q

Osteoma: Radiography (3).

A

Radiodense.

Circumscribed; no destructive features.

Involves surface or medulla of bone.

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3
Q

Osteoma: Behavior.

A

Rarely recurs.

No malignant transformation.

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4
Q

Osteoma: Histology.

A

Dense lamellar bone.

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5
Q

Osteoid osteoma: Age group.

A

Second and third decades.

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6
Q

Osteoid osteoma: Sites (3).

A

Proximal femur.

Vertebrae.

Small bones of hands and feet.

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7
Q

Osteoid osteoma: Presentations (2).

A

Classic: Pain that is worse at night and relieved by aspirin.

Tumor in hand or foot: Clinically mimics osteomyelitis or arthritis.

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8
Q

Osteoid osteoma: Radiography (2).

A

Cortical radiolucent nidus, usually less than 1 cm in diameter, surrounded by sclerosis.

Plain radiographs miss about 25% of tumors.

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9
Q

Osteoid osteoma: Histology of nidus (3).

A

Interlacing trabeculae that are

  • Variably mineralized.
  • Rimmed by osteoblasts.
  • Surrounded by fibrovascular stroma that contains multinucleate giant cells.
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10
Q

Osteoid osteoma: Histology of periphery.

A

Fibrovascular tissue surrounded by compact lamellar bone.

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11
Q

Osteoid osteoma: What should not be seen within the tumor (3).

A

Cartilage, unless there had been a fracture.

Marrow elements.

Fat.

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12
Q

Osteoid osteoma: Preoperative aids to recognition.

A

Identification of the nidus may be facilitated by

  • Tetracycline: Nidus becomes fluorescence in UV light.
  • Tc-99m.
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13
Q

Osteoid osteoma: Mutation.

A

Partial deletion of 22q in some cases.

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14
Q

Osteoid osteoma: Immunohistochemistry.

A

Some cases express c-fos and c-jun.

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15
Q

Osteoid osteoma vs. stress fracture.

A

Stress fracture:

  • Dense, mature bone is in the center.
  • Woven bone is in the periphery.
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16
Q

Osteoid osteoma: Why painful (3)?

A

Unmyelinated axons in the nidus.

Production of prostaglandin E2.

Production of prostacyclin.

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17
Q

Osteoblastoma: Age group.

A

Occurs mainly in the second and third decades.

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18
Q

Osteoblastoma: Sites

A

Vertebral column and sacrum.

Mandible and other bones of the skull.

Extremities.

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19
Q

Osteoblastoma:

A. Location in bone.
B. Presentation.

A

A. In the medulla.

B. Not as painful as osteoid osteoma.

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20
Q

Osteoblastoma: Radiography (2).

A

Expansile radiolucent zone (nidus) with a sclerotic rim.

Nidus is more than 1.5 cm in diameter.

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21
Q

Osteoblastoma: Variations on radiography (3).

A

Formation of new bone around tumor.

Cortical destruction that mimics osteosarcoma.

Secondary aneurysmal cyst.

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22
Q

Osteoblastoma: Gross pathology (3).

A

Similar to that of osteoid osteoma, but osteoblastoma is larger.

Variations:

  • Cortical thinning.
  • Hemorrhagic (secondary aneurysmal) cyst.
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23
Q

Osteoblastoma: Histology (4).

A

Irregular osteoid with rimmed by bland osteoblasts.

Osteoid merges into that of normal bone.

Osteoblasts can be mitotically active.

Fibrous stroma containing multinucleate osteoclast-like giant cells.

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24
Q

Osteoblastoma: Variations on histology (2).

A

Variable mineralization of osteoid.

Large blood lakes (secondary aneurysmal bone cysts).

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25
Q

Epithelioid osteoblasts:

A. Cytology.
B. Significance.

A

A. Much cytoplasm, large nuclei, large nucleoli.

B. If they constitute more than 75% of the tumor, then it should be called aggressive osteoblastoma, which is more likely to recur.

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26
Q

Bizarre osteoblastoma:

A. Synonym.
B. Histology.

A

A. Pseudo-malignant osteoblastoma.

B. Contains bizarre multinucleate giant cells without mitotic activity.

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27
Q

Osteoblastoma vs. osteoblastic osteosarcoma

A

Osteoblastic osteosarcoma:

  • Sarcomatoid stroma.
  • Osteoblasts form sheets or aggregates rather than a rim.
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28
Q

Conventional intramedullary osteosarcoma: Sites (3).

A

Metaphyseal:

  • Distal femur.
  • Proximal tibia.
  • Proximal humerus.
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29
Q

Conventional intramedullary osteosarcoma: Sites in Paget’s disease (3).

A

Bones of the skull.

Ribs.

Vertebrae.

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30
Q

Conventional intramedullary osteosarcoma: Age groups.

A

Mainly the second decade.

Some cases occur after 50 years of age.

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31
Q

Conventional intramedullary osteosarcoma: Presentation (2).

A

Weeks to months of mild, intermittent pain.

Presentation with a pathologic fracture is rare.

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32
Q

Conventional intramedullary osteosarcoma: Laboratory finding.

A

Elevated serum alkaline phosphatase.

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33
Q

Conventional intramedullary osteosarcoma: Radiography (2).

A

Lytic, sclerotic, or both.

Metaphyseal.

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34
Q

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

A

Codman’s triangle.

Sunburst.

Onion-skin appearance.

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35
Q

Conventional intramedullary osteosarcoma: Gross pathology (2).

A

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.

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36
Q

Conventional intramedullary osteosarcoma: Basic histology (2).

A

Malignant osteoblasts producing osteoid.

Sarcomatous stroma that may exhibit heterologous differentiation.

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37
Q

Conventional intramedullary osteosarcoma: Normalization.

A

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

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38
Q

Conventional intramedullary osteosarcoma: Chondroid and fibroblastic types.

A

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

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39
Q

Conventional intramedullary osteosarcoma: Giant-cell-rich type.

A

Rich in osteoclast-like giant cells.

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40
Q

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

A

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

Identified by IHC or by the demonstration of osteoid.

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41
Q

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

A

Acellular osteoid, acellular chondroid tissue.

Fibrosis.

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42
Q

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

A

More than 90% of the tumor is necrotic.

The cells have gone from predominantly aneuploid to predominantly diploid.

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43
Q

Conventional intramedullary osteosarcoma: Immunohistochemistry.

A

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

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44
Q

Conventional intramedullary osteosarcoma: Mutated genes.

A

Hereditary tumors: RB.

Non-hereditary: TP53 in some.

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45
Q

Conventional intramedullary osteosarcoma vs. low-grade conventional chondrosarcoma.

A

The chondroid areas of osteosarcoma are usually high-grade.

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46
Q

Conventional intramedullary osteosarcoma vs. dedifferentiated chondrosarcoma.

A

The chondroid areas of osteosarcoma are usually high-grade.

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

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47
Q

Conventional intramedullary osteosarcoma vs. clear-cell chondrosarcoma.

A

Clear-cell chondrosarcoma:

  • Clear cells.
  • Epiphyseal location.
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48
Q

Most common malignant tumors in adolescents (4).

A

Leukemia.

Brain tumors.

Lymphoma.

Osteosarcoma.

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49
Q

Telangiectatic osteosarcoma: Main age group.

A

Second decade.

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50
Q

Telangiectatic osteosarcoma: Sites.

A

Metaphyseal:

  • Distal femur.
  • Proximal tibia.
  • Proximal humerus.
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51
Q

Telangiectatic osteosarcoma: Presentation.

A

More likely than conventional osteosarcoma to cause pathologic fracture.

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52
Q

Telangiectatic osteosarcoma: Radiography (2).

A

Purely lytic.

Periosteal reaction like that of conventional osteosarcoma.

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53
Q

Telangiectatic osteosarcoma: Gross pathology.

A

Hemorrhagic mass that may be multicystic and necrotic.

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54
Q

Telangiectatic osteosarcoma: Histology (4).

A

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.

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55
Q

Telangiectatic osteosarcoma: Immunohistochemistry.

A

Positive: SATB2.

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56
Q

Telangiectatic osteosarcoma vs. aneurysmal bone cyst.

A

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

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57
Q

Telangiectatic osteosarcoma: Association.

A

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

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58
Q

Telangiectatic osteosarcoma: Prognosis.

A

Better than that of conventional osteosarcoma.

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59
Q

Parosteal osteosarcoma: Synonym.

A

Juxtacortical osteosarcoma.

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60
Q

Parosteal osteosarcoma: Sites.

A

Metaphyseal:

  • Distal femur.
  • Proximal tibia.
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61
Q

Parosteal osteosarcoma: Presentation (2).

A

Painless mass of long duration.

Inability to flex the knee.

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62
Q

Parosteal osteosarcoma: Radiography (3).

A

Radiodense boss or fungiform mass arising outside the periosteum.

Radiolucency may separate tumor from cortex (“string sign”).

No periosteal reaction.

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63
Q

Parosteal osteosarcoma: Radiolucency within the tumor (2).

A

Peripheral: May represent cartilage cap.

Central: May represent high-grade sarcoma.

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64
Q

Parosteal osteosarcoma: Histology

A

Parallel arrays of tumor osteoid.

Bland, hypocellular, fibroblastic stroma.

Cartilaginous cap or islands of cartilage containing mildly atypical, disordered chondrocytes.

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65
Q

Parosteal osteosarcoma: Variant histology.

A

Areas of dedifferentiation to high-grade sarcoma.

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66
Q

Parosteal osteosarcoma: What should not be seen histologically (2).

A

Periosteal reaction.

Fat or marrow.

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67
Q

Parosteal osteosarcoma vs. osteochondroma

A

Osteochondroma: Association of tumor with fat or marrow.

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68
Q

Parosteal osteosarcoma vs. myositis ossificans.

A

Myositis ossificans: Bone is maturer on the periphery than in the center.

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69
Q

Parosteal osteosarcoma vs. high-grade surface osteosarcoma.

A

High-grade surface osteosarcoma: No residual low-grade tumor.

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70
Q

Parosteal osteosarcoma vs. periosteal osteosarcoma (2).

A

Periosteal osteosarcoma:

  • Contains more cartilage that is more malignant.
  • Periosteal reaction.
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71
Q

Periosteal osteosarcoma: Sites.

A

Diaphysis or metaphysis:

  • Tibia.
  • Femur.
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72
Q

Periosteal osteosarcoma: Presentation.

A

Pain and swelling, usually for less than a year.

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73
Q

Periosteal osteosarcoma: Radiography (4).

A

Radiolucent.

Spiculated pattern of perpendicular calcifications.

There may be a periosteal reaction.

Medulla is not involved.

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74
Q

Periosteal osteosarcoma: Gross pathology.

A

Lobulated, cartilaginous-appearing mass on the surface.

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75
Q

Periosteal osteosarcoma: Histology (3).

A

Consists mainly of lobules of cartilage with features of grade 2 or grade 3 chondrosarcoma.

Malignant osteoid is an essentially but minor component.

There may be anaplastic stromal cells between cartilaginous lobules.

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76
Q

Periosteal osteosarcoma vs. conventional intramedullary osteosarcoma.

A

The latter involves the medullary cavity.

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77
Q

Periosteal osteosarcoma vs. high-grade surface osteosarcoma.

A

High-grade surface osteosarcoma lacks cartilaginous differentiation.

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78
Q

High-grade surface osteosarcoma: Sites (3).

A

Distal and middle femur.

Proximal humerus.

Proximal fibula.

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79
Q

High-grade surface osteosarcoma: Prognosis.

A

Similar to that of conventional intramedullary osteosarcoma.

Worse than that of parosteal osteosarcoma.

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80
Q

High-grade surface osteosarcoma: Radiography (3).

A

Similar to that of periosteal osteosarcoma, but with fluffy, “cumulus cloud” calcification.

Can cause a periosteal reaction.

No more than focal involvement of the medulla.

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81
Q

High-grade surface osteosarcoma: Histology.

A

High-grade, similar to that of conventional osteosarcoma, but without significant involvement of the marrow.

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82
Q

Low-grade central osteosarcoma: Sites (2).

A

Middle or distal femur.

Proximal or middle tibia.

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83
Q

Low-grade central osteosarcoma: Association.

A

Fibrous dysplasia.

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84
Q

Low-grade central osteosarcoma: Radiography (4).

A

Intramedullary.

Poorly circumscribed.

Sclerotic or trabeculated.

Usually no periosteal reaction.

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85
Q

Low-grade central osteosarcoma: Histology (3).

A

Irregular bony trabeculae.

Stroma consisting of bland fibroblast-like cells with visible nucleoli.

Rare chondroid foci may be visible.

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86
Q

Low-grade central osteosarcoma vs. fibrous dysplasia.

A

Fibrous dysplasia:

  • Radiographically benign.
  • Smooth, delicate trabeculae.
  • No nuclear atypia, no mitotic activity.
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87
Q

Low-grade central osteosarcoma vs. desmoplastic fibroma.

A

Desmoplastic fibroma: No osteoid in the center.

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88
Q

Low-grade central osteosarcoma vs. fibroblastic variant of conventional intramedullary osteosarcoma.

A

The latter has greater atypia and more mitotic activity.

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89
Q

Low-grade central osteosarcoma vs. parosteal osteosarcoma.

A

Parosteal osteosarcoma: Similar histology but does not involve the medulla.

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90
Q

Most common tumor of bone.

A

Osteochondroma.

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91
Q

Osteochondroma: Synonym.

A

Exostosis.

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92
Q

Osteochondroma: Sites (4).

A

Metaphyseal:

  • Distal femur.
  • Proximal tibia.
  • Humerus.
  • Pelvis.
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93
Q

Osteochondroma: Syndromes

A

Osteochondromatosis (a.k.a. multiple hereditary exostosis): Autodomal dominant.

Langer-Giedion syndrome.

DEFECT-11 syndrome.

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94
Q

Osteochondroma: Frequency of malignant transformation.

A

Less than 2%.

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95
Q

Osteochondroma: Radiography (3).

A

Pedunculated mass pointing toward the diaphysis.

Cortex and medulla are continuous with that of the bone.

Cartilaginous cap may be seen only on MRI.

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96
Q

Osteochondroma: Histology (3).

A

Outermost surface: Periosteal fibrous tissue.

Chondrocytes of the cap are evenly distributed but may exhibit atypia.

Rows and columns of chondrocytes at the junction with bone.

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97
Q

Osteochondroma: Histologic indicators of malignancy (5).

A

Increased cellularity.

Multinucleation.

High mitotic rate.

Open chromatin.

Fibroblastic stroma replaces marrow.

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98
Q

Osteochondroma: Radiologic indicators of malignancy (4).

A

Cartilaginous cap more than 2 cm thick.

Radiolucency in the cap.

Extension into soft tissue.

Destruction of bone.

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99
Q

Osteochondroma: Genes.

A

EXT1 in Langer-Giedion syndrome.

EXT2 in DEFECT-11 syndrome.

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100
Q

Osteochondroma vs. parosteal osteochondromatous proliferation.

A

Parosteal osteochondromatous proliferation:

  • No continuity with medullary cavity.
  • Mitotically active spindle cells between the lobules of cartilage.
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101
Q

Osteochondroma: Clinical indicators of malignancy (4).

A

Pain.

Rapid growth.

Size greater than 6 cm.

Location in axial skeleton.

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102
Q

Osteosarcoma: Associations (4).

A

Hereditary retinoblastoma.

Li-Fraumeni syndrome.

Ollier’s disease.

Paget’s disease.

Many others.

103
Q

Enchondroma: Sites.

A

Hands and feet.

Proximal humerus, proximal femur, distal femur.

104
Q

Osteoma: Syndrome of multiplicity.

A

Gardner’s syndrome.

105
Q

Osteoma: Age at peak incidence.

A

Fourth and fifth decades.

106
Q

Enchondroma: Radiography (3).

A

Well-defined, usually lobulated, radiolucency.

Variably mineralized.

Intact cortex; periosteal reaction is rare.

107
Q

Enchondroma: General histology.

A

Consists of lobules of bland, mitotically inactive cartilage within a bone.

108
Q

Enchondroma: Regional variation of histology.

A

Tumors in the hands and feet may have

  • More cells.
  • Myxoid change.
109
Q

Enchondroma: Special stain.

A

Ki-67: Low proliferative index (except in tumors of hands and feet).

110
Q

Enchondroma: Mutation.

A

Some patients: Rearrangement involving HMGA2 on 12q15.

111
Q

Enchondroma vs. low-grade chondrosarcoma: Presentation.

A

Pain:

  • Usually present in low-grade chondrosarcoma.
  • Usually absent in enchondroma.
112
Q

Enchondroma vs. low-grade chondrosarcoma: Radiography (3).

A

Low-grade chondrosarcoma:

  • Cortical destruction.
  • Cortical thickening due to infiltration.
  • Soft-tissue mass.
113
Q

Enchondroma vs. low-grade chondrosarcoma: Histology (2).

A

Low-grade chondrosarcoma:

  • There may be myxoid change.
  • Increased staining for Ki-67.
114
Q

Enchondroma: Syndromes.

A

Ollier’s disease.

Maffucci’s syndrome: Multiple enchondroma sand vascular tumors and risk of their malignant equivalents.

115
Q

Periosteal chondroma: Sites (4).

A

Near insertions of tendons:

  • Proximal humerus.
  • Proximal femur.
  • Distal femur.
  • Hand.
116
Q

Periosteal chondroma: Radiography.

A

Cup-shaped (due to peripheral buttress of bone) periosteal mass that does not involve the medulla.

117
Q

Periosteal chondroma: Histology.

A

Similar to that of enchondroma, but may have

  • More cells.
  • More atypia.
  • More multinucleate chondrocytes.
  • Myxoid change.
118
Q

Periosteal chondroma vs. juxtacortical chondrosarcoma.

A

Juxtacortical chondrosarcoma: Radiographic features of malignancy, including extension into soft tissue.

119
Q

Periosteal chondroma vs. periosteal osteosarcoma (2).

A

Periosteal osteosarcoma:

  • Perpendicular feathery calcifications rather than peripheral buttress.
  • Contains tumor osteoid.
120
Q

Epiphyseal tumors.

A

Chondroblastoma.

Clear-cell chondrosarcoma.

Giant-cell tumor of bone.

121
Q

Chondroblastoma: Age group.

A

Skeletally immature patients.

95% occur between the ages of 5 and 25.

122
Q

Chondroblastoma: Sites (3).

A

Epiphysis:

  • Distal femur.
  • Proximal tibia.
  • Proximal humerus.
123
Q

Chondroblastoma: Radiography (3).

A

Lytic mass rimmed by sclerotic bone.

Variable calcification.

No marked periosteal reaction.

124
Q

Chondroblastoma: Cellular components (3).

A

Stromal cells (immature chondroblasts): “Fried-egg” appearance.

Multinucleate giant cells.

Chondrocytes in a chondroid matrix.

125
Q

Chondroblastoma: Variant cytology (2).

A

Stromal cells may

  • Form syncytia.
  • Show nuclear enlargement with atypia.
126
Q

Chondroblastoma: Patterns of calcification (2).

A

Chicken-wire calcification around the stromal cells.

Coarse calcification of the chondroid matrix.

127
Q

Chondroblastoma: Immunohistochemstry.

A

S100

  • Highlights the stromal cells.
  • May be useful in tumors that are obscured by secondary aneurysmal bone cyst.
128
Q

Chondroblastoma vs. chondromyxoid fibroma (3).

A

Chondromyxoid fibroma:

  • Metaphyseal.
  • No calcifications.
  • More myxoid matrix.
129
Q

Chondroblastoma vs. giant-cell tumor of bone (2).

A

Giant-cell tumor of bone:

  • Stromal cells do not express S100 and have no nuclear grooves.
  • No chondroid matrix.
130
Q

Chondroblastoma vs. clear-cell chondrosarcoma (3).

A

Clear-cell chondrosarcoma:

  • Usually in older patients.
  • Malignant chondrocytes.
  • More calcification.
131
Q

Chondromyxoid fibroma: Sites.

A

Metaphyseal:

  • Distal femur.
  • Proximal tibia.
  • Pelvis.
132
Q

Chondromyxoid fibroma: Radiography (3).

A

Completely lytic.

Well-defined, scalloped margins.

Calcifications are not evident.

133
Q

Chondromyxoid fibroma: Histology (4).

A

Lobules of spindle or stellate cells in a myxoid matrix.

Periphery of lobules is hypercellular; cells resemble chondroblasts.

Fibrovascular separates lobules and may contain osteoid.

Calcifications may obscure architecture.

134
Q

Chondromyxoid fibroma: Cytology (3).

A

Bizarre cells in some cases.

Few or no mitotic figures.

Multinucleate giant cells in the fibrovascular stroma.

135
Q

Chondromyxoid fibroma: Mutation.

A

Recurrent anomalies of 6q25.

136
Q

Chondromyxoid fibroma vs. intramedullary chondrosarcoma: Radiography (2).

A

Intramedullary chondrosarcoma:

  • Visible calcifications.
  • Poor circumscription.
137
Q

Chondromyxoid fibroma vs. intramedullary chondrosarcoma: Histology (2).

A

Intramedullary chondrosarcoma:

  • Many mitotic figures.
  • Usually no multinucleate giant cells in the fibrovascular stroma.
138
Q

Intramedullary chondrosarcoma: Sites (4).

A

Pelvis.

Ribs.

Proximal femur.

Proximal humerus.

139
Q

Intramedullary chondrosarcoma: Radiography (3).

A

Radiolucent.

Variable calcification.

No periosteal reaction.

140
Q

Intramedullary chondrosarcoma: Gross pathology.

A

Lobulated mass that resembles cartilage.

Presence of fleshy tissue indicates high-grade component.

141
Q

Intramedullary chondrosarcoma: Cytology features chondrocytes that indicate malignancy (3).

A

Open chromatin, visible nucleoli, mitotic figures.

142
Q

Intramedullary chondrosarcoma: Other cytologic features (2).

A

Chondrocytes form clusters and may contain many nuclei.

143
Q

Intramedullary chondrosarcoma: Grade 1 (4).

A

Low cellularity.

Rare multinucleate chondrocytes.

Small, dark nuclei.

No mitotic figures.

144
Q

Intramedullary chondrosarcoma: Grade 2 (4).

A

Increased cellularity at the periphery.

More multinucleate chondrocytes.

Mild nuclear atypia.

Rare mitotic figures.

145
Q

Intramedullary chondrosarcoma: Grade 3 (4).

A

Increased cellularity overall.

Large, pleomorphic nuclei with visible nucleoli.

More mitotic figures.

There may be much necrosis.

146
Q

Intramedullary chondrosarcoma: Immunohistochemistry.

A

Poorly differentiated foci may not express S100.

147
Q

Intramedullary chondrosarcoma: Ploidy.

A

Grade 1: Diploid.

Grade 2: Diploid or aneuploid.

Grade 3: Aneuploid.

148
Q

Intramedullary chondrosarcoma: Other cytogenetic abnormalities (2).

A

+20q, +8q.

149
Q

Intramedullary chondrosarcoma, grade 1, vs. enchondroma.

A

Enchondroma:

  • Normal hematopoietic tissue separates the lobules of chondroid tissue.
  • Distinction requires correlation with clinical and radiologic impression.
150
Q

Intramedullary chondrosarcoma: Significance of endochondral ossification.

A

Endochondral ossification does not make it an osteosarcoma.

151
Q

Intramedullary chondrosarcoma vs. benign cartilaginous tumor: Anatomical clue.

A

Hands and feet: Generally benign.

Axial skeleton: Usually aggressive.

152
Q

Intramedullary chondrosarcoma vs. benign cartilaginous tumor: Clinical clue.

A

If pain, then more likely to be malignant.

153
Q

Secondary chondrosarcoma: Backgrounds (4).

A

Fibrous dysplasia.

Enchondromatosis.

Maffucci’s syndrome.

Osteochondroma.

154
Q

Dedifferentiated chondrosarcoma: Age group.

A

Most patients are older than 50 years.

155
Q

Dedifferentiated chondrosarcoma: Presentation.

A

Recent increase in pain due to rapid growth of tumor.

Pathologic fracture in most patients.

156
Q

Dedifferentiated chondrosarcoma: Radiography.

A

Poorly defined lytic area.

Superimposed radiodensity containing calcifications.

157
Q

Dedifferentiated chondrosarcoma: Gross pathology.

A

Component of chondroid tissue.

Component of soft, fleshy, tan-yellow tissue.

158
Q

Dedifferentiated chondrosarcoma: Histology.

A

Abrupt transition between

  • Chondroid component: Grade 1 chondroid neoplasm (usually) or grade 2.
  • Dedifferentiated component: Sarcomatoid, sometimes with heterologous differentiation.
159
Q

Dedifferentiated chondrosarcoma: Immunohistochemistry (2).

A

Chondroid component express S100.

Dedifferentiated component expresses sarcoma-related markers (e.g. SMA, CD68).

160
Q

Dedifferentiated chondrosarcoma: Ploidy.

A

Chondroid component: Diploid.

Dedifferentiated component: Aneuploid.

161
Q

Dedifferentiated chondrosarcoma vs. mesenchymal chondrosarcoma (2).

A

Mesenchymal chondrosarcoma:

  • More gradual transition between components.
  • Hemangiopericytoma-like vascular pattern.
162
Q

Dedifferentiated chondrosarcoma: Prognosis.

A

Dedifferentiated chondrosarcoma containing MFH component has a worse prognosis than primary MFH.

163
Q

Mesenchymal chondrosarcoma: Age group.

A

About 80% of cases occur between 10 and 40 years of age.

164
Q

Mesenchymal chondrosarcoma: Sites (5).

A

Maxilla.

Mandible.

Ribs.

Vertebrae.

Pelvis.

165
Q

Mesenchymal chondrosarcoma: Radiography.

A

Radiolucency with variable mineralization.

166
Q

Mesenchymal chondrosarcoma: Histology.

A

Gradual transition between

  • Chondroid component: Bland hyaline cartilage.
  • Mesenchymal component: Small round blue cells primitive spindle cells surrounding vessels like those of HPC.
167
Q

Mesenchymal chondrosarcoma: Immunohistochemistry (5).

A

Chondroid component expresses S100.

Mesenchymal component

  • Expresses Sox9.
  • May express CD99 in small cells.
  • May express NSE in primitive cells.
  • Expresses desmin and MSA is there is rhabdomyoblastic differentiation.
168
Q

Mesenchymal chondrosarcoma: Translocations (2).

A

t(11;22)(q24;q12) as in Ewing’s sarcoma.

t(13;21)(q10;q10) in some tumors.

169
Q

Clear-cell chondrosarcoma: Sites (3).

A

Epiphyseal:

  • Proximal femur.
  • Proximal humerus.
  • Distal femur.
170
Q

Clear-cell chondrosarcoma: Radiography (2).

A

Discrete lytic lesion with a sclerotic rim.

Cortex is usually intact.

171
Q

Clear-cell chondrosarcoma: Cytology (3).

A

Nucleus:

  • Vesicular chromatin.
  • Large nucleolus.

Cytoplasm:

  • Abundant, clear.
  • Discrete borders.

Few mitotic figures.

172
Q

Clear-cell chondrosarcoma: Histology

A

Chondroid matrix.

Scattered bony trabeculae or woven bone in the matrix.

Half of cases contain conventional chondrosarcoma.

173
Q

Clear-cell chondrosarcoma: Special stain.

A

PAS highlights glycogen in the clear cells.

174
Q

Clear-cell chondrosarcoma vs. chondroblastoma (2).

A

Chondroblastoma:

  • Few or no clear cells.
  • No bony trabeculae.
175
Q

Hemangioma of bone: Sites (2).

A

Cranial bones.

Vertebrae.

176
Q

Hemangioma of bone: Presentations (2).

A

Often symptomatic.

May compress facial nerve, spinal cord, or spinal nerve roots.

177
Q

Hemangioma of bone: Radiography of cranial tumors (2).

A

Lytic mass with sunburst pattern.

Bulging of inner and outer tables.

178
Q

Hemangioma of bone: Radiography of vertebral tumors (2).

A

Lytic mass with vertical striations.

CT: “Polka-dot” pattern.

179
Q

Hemangioma of bone: Types.

A

Cavernous.

Cavernous + capillary.

Pure capillary (rare).

180
Q

Hemangioma of bone: Secondary changes (2).

A

Thrombosis leading to papillary endothelial hyperplasia: May be confused with angiosarcoma.

Epithelioid change in endothelial cells: May be confused with epithelioid hemangioendothelioma.

181
Q

Hemangioma of bone: Histology of periphery.

A

Osteoclastic reabsorption of trabecular bone.

182
Q

Massive osteolysis.

A

Aggressive angiomatosis affecting mainly the bones of the trunk of children and young adults.

183
Q

Epithelioid hemangioendothelioma: Sites (3).

A

Lower extremities.

Axial skeleton.

Skull.

Usually multifocal within the same and/or different bones.

184
Q

Epithelioid hemangioendothelioma: Radiography.

A

Discrete radiolucency with sclerotic rim.

185
Q

Epithelioid hemangioendothelioma: Histology (4).

A

Epithelioid cells firm cords, nests, and anastomosing vessels.

Intracytoplasmic vacuoles that may contain erythrocytes.

Mixed inflammatory infiltrate that includes eosinophils.

Myxoid or chondroid-like stroma.

186
Q

Epithelioid hemangioendothelioma: Immunohistochemistry (1,2).

A

Positive: Vascular markers.

Variable: EMA, cytokeratin.

187
Q

Epithelioid hemangioendothelioma vs. angiosarcoma (3).

A

Angiosarcoma:

  • More pleomorphism.
  • More mitotic figures.
  • Cells form tufts or bridges that span the lumens.
188
Q

Epithelioid hemangioendothelioma vs. cartilaginous tumor.

A

The chondroid-like matrix of epithelioid hemangioendothelioma do not express S100 and may express vascular markers.

189
Q

Solitary fibrous tumor: Sites (2).

A

Axial skeleton.

Lower extremities.

190
Q

Solitary fibrous tumor: Histology.

A

Solid proliferation of spindle cells surrounding staghorn vessels.

Variable mitotic activity, nuclear atypia, necrosis.

191
Q

Solitary fibrous tumor: Best predictor of malignancy.

A

Presence of more than 4 mitotic figures per 10 hpf.

192
Q

Solitary fibrous tumor: Immunohistochemistry (2,2).

A

Positive: CD34, STAT6.

Negative: CD99, vimentin.

193
Q

Solitary fibrous tumor: Special stain.

A

Reticulin stain reveals fibers around “pericytes”.

194
Q

Solitary fibrous tumor:

A. Mutation.
B. How best to detect the mutation.

A

A. Fusion of NAB2 and STAT6, both on 12q13.

B. IHC; FISH is not useful.

195
Q

Solitary fibrous tumor: Differential diagnosis (6).

A

Metastatic solitary fibrous tumor.

Mesenchymal chondrosarcoma.

MFH.

Angioblastic meningioma.

Small-cell osteosarcoma.

Synovial sarcoma.

GIST.

196
Q

Hemangioma of bone: Immunohistochemistry (4).

A

Positive: CD31, CD34, factor VIII, ERG.

197
Q

Angiosarcoma: Associations (3).

A

Previous infarct of bone.

Chronic osteomyelitis.

Irradiation.

198
Q

Fibrous dysplasia: Sites (7).

A

Monostotic form (90%): Skull, femur, tibia, ribs.

Polyostotic form: Femur, tibia, pelvis.

199
Q

Fibrous dysplasia: Presentation.

A

Polyostotic form: Pain and recurrent fractures in childhood.

200
Q

Fibrous dysplasia: Presentation according to anatomical site (3).

A

Skull: Facial deformities.

Long bones: Recurrent fractures with “shepherd’s crook” deformity.

Ribs: Usually asymptomatic.

201
Q

Fibrous dysplasia: Syndromes (3).

A

McCune-Albright.

Cherubism.

Mazabraud’s.

202
Q

McCune-Albright syndrome (4).

A

Fibrous dysplasia.

Precocious puberty.

Hyperthyroidism.

Café-au-lait macules (“coast of Maine”).

203
Q

Cherubism.

A

Fibrous dysplasia mainly affecting the jaws.

Many giant cells.

204
Q

Mazabraud’s syndrome.

A

Fibrous dysplasia.

Myxomas of soft tissue.

205
Q

Fibrous dysplasia: Location in bone.

A

Intramedullary; diaphysis or metaphysis.

206
Q

Fibrous dysplasia: Radiography.

A

Intramedullary mass causing cortical expansion.

207
Q

Fibrous dysplasia: Locational variation.

A

Surface of bone: Fibrous dysplasia protuberans.

208
Q

Fibrous dysplasia: Histology of trabeculae (3).

A

Resemble “Chinese letters”.

No osteoblastic rimming.

Mineralization may form laminated structures that resemble cementoid bodies.

209
Q

Fibrous dysplasia: Histology of stroma.

A

Consists of fibroblastic spindle cells in a storiform pattern.

210
Q

Fibrous dysplasia: Histology of periphery.

A

Reactive bone with osteoblastic rimming.

211
Q

Fibrous dysplasia: Histologic variation.

A

Foci of cartilaginous differentiation: Fibrocartilaginous dysplasia.

212
Q

Fibrous dysplasia: Affected gene.

213
Q

Fibrous dysplasia: Complication.

A

Fibrosarcoma, osteosarcoma, chondrosarcoma, or MFH may arise from it.

214
Q

Fibrous dysplasia vs. desmoplastic fibroma.

A

Desmoplastic fibroma: No woven bone.

215
Q

Osteofibrous dysplasia: Synonym.

A

Ossifying fibroma of long bones.

216
Q

Osteofibrous dysplasia: Age group.

A

Mostly children under the age of 5 years.

217
Q

Osteofibrous dysplasia: Sites.

A

Anterior surface of tibia or of fibula.

218
Q

Osteofibrous dysplasia: Histology (3).

A

Similar to that of fibrous dysplasia but with

  • Osteoblastic rimming.
  • Simpler shapes of trabeculae.
  • Maturation of bone.
219
Q

Osteofibrous dysplasia: Radiography.

A

Cortical; diaphysis.

220
Q

Osteofibrous dysplasia vs. osteosarcoma.

A

Osteosarcoma: The stromal spindle cells show nuclear atypia.

221
Q

Osteofibrous dysplasia: Complication.

A

No known malignant transformation.

222
Q

Nonossifying fibroma: Synonyms (2).

A

Fibrous cortical defect.

Metaphyseal fibrous defect.

223
Q

Nonossifying fibroma: Typical presentation.

A

Asymptomatic.

224
Q

Nonossifying fibroma: Radiography.

A

Cortical; metaphyseal; lytic lesion with sclerotic margin.

225
Q

Nonossifying fibroma: Histology (4).

A

Fibroblastic spindle cells, sometimes in a storiform pattern.

Few mitotic figures.

Changes reminiscent of aneurysmal bone cyst.

Foci of necrosis or of reactive bone.

226
Q

Nonossifying fibroma vs. benign fibrous histiocytoma.

A

Benign fibrous histiocytoma:

  • Identical histology.
  • Term used when lesion occurs in ribs, vertebrae, or flat bones.
227
Q

Nonossifying fibroma: Syndromes (2).

A

Neurofibromatosis.

Jaffe-Campanacci syndrome.

228
Q

Desmoplastic fibroma: Sites.

A

Chin.

Pelvis.

Humerus.

Femur.

Tibia.

229
Q

Desmoplastic fibroma: Histology.

A

Resembles a fibromatosis set among bony trabeculae.

230
Q

Desmoplastic fibroma: Cytogenetics.

231
Q

Desmoplastic fibroma vs. low-grade fibrosarcoma.

A

The latter diagnosis should be considered if there are more than rare mitotic figures.

232
Q

Fibrosarcoma: Histology of grade 1 (3).

A

Bland fibroblasts.

No more than 4 mitotic figures per hpf.

Much collagen.

233
Q

Fibrosarcoma: Histology of grade 2 (3).

A

More nuclear atypia.

More mitotic figures.

More cells; less collagen.

234
Q

Fibrosarcoma: Histology of grade 3 (3).

A

Markedly atypical nuclei with large nucleoli.

Brisk mitotic activity, with atypical forms.

Necrosis, hemorrhage, myxoid change.

235
Q

Fibrosarcoma: Mutation.

A

Gain of PDGFB at 22q12-q13.

236
Q

Fibrosarcoma vs. desmoplastic fibroma (3).

A

Desmoplastic fibroma:

  • Storiform rather than herringbone pattern.
  • Contains tumor osteoid.
  • No mitotic activity, no pleomorphism.
237
Q

Fibrosarcoma: Most common antecedent.

A

Irradiation of a giant-cell tumor of bone.

238
Q

Malignant fibrous histiocytoma: Iatrogenic antecedents (2).

A

Irradiation of bone.

Metallic prosthesis.

239
Q

Malignant fibrous histiocytoma: Most common types seen in bone.

A

Storiform-pleomorphic.

Giant-cell-rich.

240
Q

Malignant fibrous histiocytoma: Histologic pitfall.

A

Thick, eosinophilic fibrillary deposits surrounding individual tumor cells may mimic tumor osteoid.

241
Q

Malignant fibrous histiocytoma, giant-cell-rich vs. giant-cell tumor of bone.

A

Giant-cell lacks significant nuclear pleomorphism and atypical mitotic figures.

242
Q

Giant-cell tumor of bone: Age group.

A

Skeletally mature young adults.

243
Q

Giant-cell tumor of bone: Sites (4).

A

Epiphyseal:

  • Distal femur.
  • Proximal tibia.
  • Distal radius.
  • Sacrum.
244
Q

Giant-cell tumor of bone: Presentation.

A

Typical: Localized pain.

Sometimes: Pathologic fracture.

245
Q

Giant-cell tumor of bone: Radiography

A

Lytic mass.

No sclerosis, no periosteal reaction.

Thin rim of bone separates expansile masses from soft tissue.

246
Q

Giant-cell tumor of bone: Histology (3).

A

Bland, multinucleate, osteoclast-like giant cells.

Bland mononuclear cells in the background.

No cartilage unless there has been a fracture.

247
Q

Giant-cell tumor of bone: Cytogenetics.

A

Telomeric association involving 19q, 1p, 15p, or other chromosomes.

248
Q

Giant-cell tumor of bone: Genes in which mutations are associated with more aggressive behavior (3).

A

C-MYC.

The gene of hepatocyte-growth-factor receptor.

The gene of VEGF.

249
Q

Giant-cell tumor of bone vs. giant-cell reparative granuloma (4).

A

Giant-cell reparative granuloma:

  • Giant cells are unevenly distributed.
  • Giant cells have fewer nuclei.
  • More fibrotic stroma.
  • Stromal cells are spindle shaped.
250
Q

Giant-cell tumor of bone vs. nonossifying fibroma (2).

A

Nonossifying fibroma:

  • Usually metaphyseal.
  • Peripheral sclerosis.
251
Q

Giant-cell tumor of bone vs. brown tumor.

A

Brown tumor: Elevated serum calcium and PTH.

252
Q

Giant-cell tumor of bone: Behavior (2).

A

Most are benign, but rare benign ones exhibit pulmonary metastases due to embolizatio of tumor.

Malignant tumors can arise from benign tumors.

253
Q

Osteoma: Sites.

A

Bones of the skull.

AP reviewer (17 decks)

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