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Anatomic pathology > Bones & Joints > Flashcards

Flashcards in Bones & Joints Deck (253):
1

Osteoma: Presentation.

May be asymptomatic.

May cause symptoms if involving sinuses or orbits.

2

Osteoma: Radiography (3).

Radiodense.

Circumscribed; no destructive features.

Involves surface or medulla of bone.

3

Osteoma: Behavior.

Rarely recurs.

No malignant transformation.

4

Osteoma: Histology.

Dense lamellar bone.

5

Osteoid osteoma: Age group.

Second and third decades.

6

Osteoid osteoma: Sites (3).

Proximal femur.

Vertebrae.

Small bones of hands and feet.

7

Osteoid osteoma: Presentations (2).

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

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

8

Osteoid osteoma: Radiography (2).

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

Plain radiographs miss about 25% of tumors.

9

Osteoid osteoma: Histology of nidus (3).

Interlacing trabeculae that are

- Variably mineralized.
- Rimmed by osteoblasts.
- Surrounded by fibrovascular stroma that contains multinucleate giant cells.

10

Osteoid osteoma: Histology of periphery.

Fibrovascular tissue surrounded by compact lamellar bone.

11

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

Cartilage, unless there had been a fracture.

Marrow elements.

Fat.

12

Osteoid osteoma: Preoperative aids to recognition.

Identification of the nidus may be facilitated by

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

13

Osteoid osteoma: Mutation.

Partial deletion of 22q in some cases.

14

Osteoid osteoma: Immunohistochemistry.

Some cases express c-fos and c-jun.

15

Osteoid osteoma vs. stress fracture.

Stress fracture:

- Dense, mature bone is in the center.
- Woven bone is in the periphery.

16

Osteoid osteoma: Why painful (3)?

Unmyelinated axons in the nidus.

Production of prostaglandin E2.

Production of prostacyclin.

17

Osteoblastoma: Age group.

Occurs mainly in the second and third decades.

18

Osteoblastoma: Sites

Vertebral column and sacrum.

Mandible and other bones of the skull.

Extremities.

19

Osteoblastoma:

A. Location in bone.
B. Presentation.

A. In the medulla.

B. Not as painful as osteoid osteoma.

20

Osteoblastoma: Radiography (2).

Expansile radiolucent zone (nidus) with a sclerotic rim.

Nidus is more than 1.5 cm in diameter.

21

Osteoblastoma: Variations on radiography (3).

Formation of new bone around tumor.

Cortical destruction that mimics osteosarcoma.

Secondary aneurysmal cyst.

22

Osteoblastoma: Gross pathology (3).

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

Variations:
- Cortical thinning.
- Hemorrhagic (secondary aneurysmal) cyst.

23

Osteoblastoma: Histology (4).

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.

24

Osteoblastoma: Variations on histology (2).

Variable mineralization of osteoid.

Large blood lakes (secondary aneurysmal bone cysts).

25

Epithelioid osteoblasts:

A. Cytology.
B. Significance.

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.

26

Bizarre osteoblastoma:

A. Synonym.
B. Histology.

A. Pseudo-malignant osteoblastoma.

B. Contains bizarre multinucleate giant cells without mitotic activity.

27

Osteoblastoma vs. osteoblastic osteosarcoma

Osteoblastic osteosarcoma:

- Sarcomatoid stroma.
- Osteoblasts form sheets or aggregates rather than a rim.

28

Conventional intramedullary osteosarcoma: Sites (3).

Metaphyseal:

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

29

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

Bones of the skull.

Ribs.

Vertebrae.

30

Conventional intramedullary osteosarcoma: Age groups.

Mainly the second decade.

Some cases occur after 50 years of age.

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.

61

Parosteal osteosarcoma: Presentation (2).

Painless mass of long duration.

Inability to flex the knee.

62

Parosteal osteosarcoma: Radiography (3).

Radiodense boss or fungiform mass arising outside the periosteum.

Radiolucency may separate tumor from cortex ("string sign").

No periosteal reaction.

63

Parosteal osteosarcoma: Radiolucency within the tumor (2).

Peripheral: May represent cartilage cap.

Central: May represent high-grade sarcoma.

64

Parosteal osteosarcoma: Histology

Parallel arrays of tumor osteoid.

Bland, hypocellular, fibroblastic stroma.

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

65

Parosteal osteosarcoma: Variant histology.

Areas of dedifferentiation to high-grade sarcoma.

66

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

Periosteal reaction.

Fat or marrow.

67

Parosteal osteosarcoma vs. osteochondroma

Osteochondroma: Association of tumor with fat or marrow.

68

Parosteal osteosarcoma vs. myositis ossificans.

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

69

Parosteal osteosarcoma vs. high-grade surface osteosarcoma.

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

70

Parosteal osteosarcoma vs. periosteal osteosarcoma (2).

Periosteal osteosarcoma:

- Contains more cartilage that is more malignant.
- Periosteal reaction.

71

Periosteal osteosarcoma: Sites.

Diaphysis or metaphysis:

- Tibia.
- Femur.

72

Periosteal osteosarcoma: Presentation.

Pain and swelling, usually for less than a year.

73

Periosteal osteosarcoma: Radiography (4).

Radiolucent.

Spiculated pattern of perpendicular calcifications.

There may be a periosteal reaction.

Medulla is not involved.

74

Periosteal osteosarcoma: Gross pathology.

Lobulated, cartilaginous-appearing mass on the surface.

75

Periosteal osteosarcoma: Histology (3).

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.

76

Periosteal osteosarcoma vs. conventional intramedullary osteosarcoma.

The latter involves the medullary cavity.

77

Periosteal osteosarcoma vs. high-grade surface osteosarcoma.

High-grade surface osteosarcoma lacks cartilaginous differentiation.

78

High-grade surface osteosarcoma: Sites (3).

Distal and middle femur.

Proximal humerus.

Proximal fibula.

79

High-grade surface osteosarcoma: Prognosis.

Similar to that of conventional intramedullary osteosarcoma.

Worse than that of parosteal osteosarcoma.

80

High-grade surface osteosarcoma: Radiography (3).

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.

81

High-grade surface osteosarcoma: Histology.

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

82

Low-grade central osteosarcoma: Sites (2).

Middle or distal femur.

Proximal or middle tibia.

83

Low-grade central osteosarcoma: Association.

Fibrous dysplasia.

84

Low-grade central osteosarcoma: Radiography (4).

Intramedullary.

Poorly circumscribed.

Sclerotic or trabeculated.

Usually no periosteal reaction.

85

Low-grade central osteosarcoma: Histology (3).

Irregular bony trabeculae.

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

Rare chondroid foci may be visible.

86

Low-grade central osteosarcoma vs. fibrous dysplasia.

Fibrous dysplasia:

- Radiographically benign.
- Smooth, delicate trabeculae.
- No nuclear atypia, no mitotic activity.

87

Low-grade central osteosarcoma vs. desmoplastic fibroma.

Desmoplastic fibroma: No osteoid in the center.

88

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

The latter has greater atypia and more mitotic activity.

89

Low-grade central osteosarcoma vs. parosteal osteosarcoma.

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

90

Most common tumor of bone.

Osteochondroma.

91

Osteochondroma: Synonym.

Exostosis.

92

Osteochondroma: Sites (4).

Metaphyseal:

- Distal femur.
- Proximal tibia.
- Humerus.
- Pelvis.

93

Osteochondroma: Syndromes

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

Langer-Giedion syndrome.

DEFECT-11 syndrome.

94

Osteochondroma: Frequency of malignant transformation.

Less than 2%.

95

Osteochondroma: Radiography (3).

Pedunculated mass pointing toward the diaphysis.

Cortex and medulla are continuous with that of the bone.

Cartilaginous cap may be seen only on MRI.

96

Osteochondroma: Histology (3).

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.

97

Osteochondroma: Histologic indicators of malignancy (5).

Increased cellularity.

Multinucleation.

High mitotic rate.

Open chromatin.

Fibroblastic stroma replaces marrow.

98

Osteochondroma: Radiologic indicators of malignancy (4).

Cartilaginous cap more than 2 cm thick.

Radiolucency in the cap.

Extension into soft tissue.

Destruction of bone.

99

Osteochondroma: Genes.

EXT1 in Langer-Giedion syndrome.

EXT2 in DEFECT-11 syndrome.

100

Osteochondroma vs. parosteal osteochondromatous proliferation.

Parosteal osteochondromatous proliferation:

- No continuity with medullary cavity.
- Mitotically active spindle cells between the lobules of cartilage.

101

Osteochondroma: Clinical indicators of malignancy (4).

Pain.

Rapid growth.

Size greater than 6 cm.

Location in axial skeleton.

102

Osteosarcoma: Associations (4).

Hereditary retinoblastoma.

Li-Fraumeni syndrome.

Ollier's disease.

Paget's disease.

Many others.

103

Enchondroma: Sites.

Hands and feet.

Proximal humerus, proximal femur, distal femur.

104

Osteoma: Syndrome of multiplicity.

Gardner's syndrome.

105

Osteoma: Age at peak incidence.

Fourth and fifth decades.

106

Osteoma: Sites.

Bones of the skull.

106

Enchondroma: Radiography (3).

Well-defined, usually lobulated, radiolucency.

Variably mineralized.

Intact cortex; periosteal reaction is rare.

107

Enchondroma: General histology.

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

108

Enchondroma: Regional variation of histology.

Tumors in the hands and feet may have

- More cells.
- Myxoid change.

109

Enchondroma: Special stain.

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

110

Enchondroma: Mutation.

Some patients: Rearrangement involving HMGA2 on 12q15.

111

Enchondroma vs. low-grade chondrosarcoma: Presentation.

Pain:
- Usually present in low-grade chondrosarcoma.
- Usually absent in enchondroma.

112

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

Low-grade chondrosarcoma:

- Cortical destruction.
- Cortical thickening due to infiltration.
- Soft-tissue mass.

113

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

Low-grade chondrosarcoma:

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

114

Enchondroma: Syndromes.

Ollier's disease.

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

115

Periosteal chondroma: Sites (4).

Near insertions of tendons:

- Proximal humerus.
- Proximal femur.
- Distal femur.
- Hand.

116

Periosteal chondroma: Radiography.

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

117

Periosteal chondroma: Histology.

Similar to that of enchondroma, but may have

- More cells.
- More atypia.
- More multinucleate chondrocytes.
- Myxoid change.

118

Periosteal chondroma vs. juxtacortical chondrosarcoma.

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

119

Periosteal chondroma vs. periosteal osteosarcoma (2).

Periosteal osteosarcoma:

- Perpendicular feathery calcifications rather than peripheral buttress.
- Contains tumor osteoid.

120

Epiphyseal tumors.

Chondroblastoma.

Clear-cell chondrosarcoma.

Giant-cell tumor of bone.

121

Chondroblastoma: Age group.

Skeletally immature patients.

95% occur between the ages of 5 and 25.

122

Chondroblastoma: Sites (3).

Epiphysis:

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

123

Chondroblastoma: Radiography (3).

Lytic mass rimmed by sclerotic bone.

Variable calcification.

No marked periosteal reaction.

124

Chondroblastoma: Cellular components (3).

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

Multinucleate giant cells.

Chondrocytes in a chondroid matrix.

125

Chondroblastoma: Variant cytology (2).

Stromal cells may

- Form syncytia.
- Show nuclear enlargement with atypia.

126

Chondroblastoma: Patterns of calcification (2).

Chicken-wire calcification around the stromal cells.

Coarse calcification of the chondroid matrix.

127

Chondroblastoma: Immunohistochemstry.

S100

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

128

Chondroblastoma vs. chondromyxoid fibroma (3).

Chondromyxoid fibroma:

- Metaphyseal.
- No calcifications.
- More myxoid matrix.

129

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

Giant-cell tumor of bone:

- Stromal cells do not express S100 and have no nuclear grooves.
- No chondroid matrix.

130

Chondroblastoma vs. clear-cell chondrosarcoma (3).

Clear-cell chondrosarcoma:

- Usually in older patients.
- Malignant chondrocytes.
- More calcification.

131

Chondromyxoid fibroma: Sites.

Metaphyseal:

- Distal femur.
- Proximal tibia.
- Pelvis.

132

Chondromyxoid fibroma: Radiography (3).

Completely lytic.

Well-defined, scalloped margins.

Calcifications are not evident.

133

Chondromyxoid fibroma: Histology (4).

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

Chondromyxoid fibroma: Cytology (3).

Bizarre cells in some cases.

Few or no mitotic figures.

Multinucleate giant cells in the fibrovascular stroma.

135

Chondromyxoid fibroma: Mutation.

Recurrent anomalies of 6q25.

136

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

Intramedullary chondrosarcoma:

- Visible calcifications.
- Poor circumscription.

137

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

Intramedullary chondrosarcoma:

- Many mitotic figures.
- Usually no multinucleate giant cells in the fibrovascular stroma.

138

Intramedullary chondrosarcoma: Sites (4).

Pelvis.

Ribs.

Proximal femur.

Proximal humerus.

139

Intramedullary chondrosarcoma: Radiography (3).

Radiolucent.

Variable calcification.

No periosteal reaction.

140

Intramedullary chondrosarcoma: Gross pathology.

Lobulated mass that resembles cartilage.

Presence of fleshy tissue indicates high-grade component.

141

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

Open chromatin, visible nucleoli, mitotic figures.

142

Intramedullary chondrosarcoma: Other cytologic features (2).

Chondrocytes form clusters and may contain many nuclei.

143

Intramedullary chondrosarcoma: Grade 1 (4).

Low cellularity.

Rare multinucleate chondrocytes.

Small, dark nuclei.

No mitotic figures.

144

Intramedullary chondrosarcoma: Grade 2 (4).

Increased cellularity at the periphery.

More multinucleate chondrocytes.

Mild nuclear atypia.

Rare mitotic figures.

145

Intramedullary chondrosarcoma: Grade 3 (4).

Increased cellularity overall.

Large, pleomorphic nuclei with visible nucleoli.

More mitotic figures.

There may be much necrosis.

146

Intramedullary chondrosarcoma: Immunohistochemistry.

Poorly differentiated foci may not express S100.

147

Intramedullary chondrosarcoma: Ploidy.

Grade 1: Diploid.

Grade 2: Diploid or aneuploid.

Grade 3: Aneuploid.

148

Intramedullary chondrosarcoma: Other cytogenetic abnormalities (2).

+20q, +8q.

149

Intramedullary chondrosarcoma, grade 1, vs. enchondroma.

Enchondroma:

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

150

Intramedullary chondrosarcoma: Significance of endochondral ossification.

Endochondral ossification does not make it an osteosarcoma.

151

Intramedullary chondrosarcoma vs. benign cartilaginous tumor: Anatomical clue.

Hands and feet: Generally benign.

Axial skeleton: Usually aggressive.

152

Intramedullary chondrosarcoma vs. benign cartilaginous tumor: Clinical clue.

If pain, then more likely to be malignant.

153

Secondary chondrosarcoma: Backgrounds (4).

Fibrous dysplasia.

Enchondromatosis.

Maffucci's syndrome.

Osteochondroma.

154

Dedifferentiated chondrosarcoma: Age group.

Most patients are older than 50 years.

155

Dedifferentiated chondrosarcoma: Presentation.

Recent increase in pain due to rapid growth of tumor.

Pathologic fracture in most patients.

156

Dedifferentiated chondrosarcoma: Radiography.

Poorly defined lytic area.

Superimposed radiodensity containing calcifications.

157

Dedifferentiated chondrosarcoma: Gross pathology.

Component of chondroid tissue.

Component of soft, fleshy, tan-yellow tissue.

158

Dedifferentiated chondrosarcoma: Histology.

Abrupt transition between

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

159

Dedifferentiated chondrosarcoma: Immunohistochemistry (2).

Chondroid component express S100.

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

160

Dedifferentiated chondrosarcoma: Ploidy.

Chondroid component: Diploid.

Dedifferentiated component: Aneuploid.

161

Dedifferentiated chondrosarcoma vs. mesenchymal chondrosarcoma (2).

Mesenchymal chondrosarcoma:

- More gradual transition between components.
- Hemangiopericytoma-like vascular pattern.

162

Dedifferentiated chondrosarcoma: Prognosis.

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

163

Mesenchymal chondrosarcoma: Age group.

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

164

Mesenchymal chondrosarcoma: Sites (5).

Maxilla.

Mandible.

Ribs.

Vertebrae.

Pelvis.

165

Mesenchymal chondrosarcoma: Radiography.

Radiolucency with variable mineralization.

166

Mesenchymal chondrosarcoma: Histology.

Gradual transition between

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

167

Mesenchymal chondrosarcoma: Immunohistochemistry (5).

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

Mesenchymal chondrosarcoma: Translocations (2).

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

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

169

Clear-cell chondrosarcoma: Sites (3).

Epiphyseal:

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

170

Clear-cell chondrosarcoma: Radiography (2).

Discrete lytic lesion with a sclerotic rim.

Cortex is usually intact.

171

Clear-cell chondrosarcoma: Cytology (3).

Nucleus:
- Vesicular chromatin.
- Large nucleolus.

Cytoplasm:
- Abundant, clear.
- Discrete borders.

Few mitotic figures.

172

Clear-cell chondrosarcoma: Histology

Chondroid matrix.

Scattered bony trabeculae or woven bone in the matrix.

Half of cases contain conventional chondrosarcoma.

173

Clear-cell chondrosarcoma: Special stain.

PAS highlights glycogen in the clear cells.

174

Clear-cell chondrosarcoma vs. chondroblastoma (2).

Chondroblastoma:

- Few or no clear cells.
- No bony trabeculae.

175

Hemangioma of bone: Sites (2).

Cranial bones.

Vertebrae.

176

Hemangioma of bone: Presentations (2).

Often symptomatic.

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

177

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

Lytic mass with sunburst pattern.

Bulging of inner and outer tables.

178

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

Lytic mass with vertical striations.

CT: "Polka-dot" pattern.

179

Hemangioma of bone: Types.

Cavernous.

Cavernous + capillary.

Pure capillary (rare).

180

Hemangioma of bone: Secondary changes (2).

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

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

181

Hemangioma of bone: Histology of periphery.

Osteoclastic reabsorption of trabecular bone.

182

Massive osteolysis.

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

183

Epithelioid hemangioendothelioma: Sites (3).

Lower extremities.

Axial skeleton.

Skull.

Usually multifocal within the same and/or different bones.

184

Epithelioid hemangioendothelioma: Radiography.

Discrete radiolucency with sclerotic rim.

185

Epithelioid hemangioendothelioma: Histology (4).

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

Epithelioid hemangioendothelioma: Immunohistochemistry (1,2).

Positive: Vascular markers.

Variable: EMA, cytokeratin.

187

Epithelioid hemangioendothelioma vs. angiosarcoma (3).

Angiosarcoma:

- More pleomorphism.
- More mitotic figures.
- Cells form tufts or bridges that span the lumens.

188

Epithelioid hemangioendothelioma vs. cartilaginous tumor.

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

189

Solitary fibrous tumor: Sites (2).

Axial skeleton.

Lower extremities.

190

Solitary fibrous tumor: Histology.

Solid proliferation of spindle cells surrounding staghorn vessels.

Variable mitotic activity, nuclear atypia, necrosis.

191

Solitary fibrous tumor: Best predictor of malignancy.

Presence of more than 4 mitotic figures per 10 hpf.

192

Solitary fibrous tumor: Immunohistochemistry (2,2).

Positive: CD34, STAT6.

Negative: CD99, vimentin.

193

Solitary fibrous tumor: Special stain.

Reticulin stain reveals fibers around "pericytes".

194

Solitary fibrous tumor:

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

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

B. IHC; FISH is not useful.

195

Solitary fibrous tumor: Differential diagnosis (6).

Metastatic solitary fibrous tumor.

Mesenchymal chondrosarcoma.

MFH.

Angioblastic meningioma.

Small-cell osteosarcoma.

Synovial sarcoma.

GIST.

196

Hemangioma of bone: Immunohistochemistry (4).

Positive: CD31, CD34, factor VIII, ERG.

197

Angiosarcoma: Associations (3).

Previous infarct of bone.

Chronic osteomyelitis.

Irradiation.

198

Fibrous dysplasia: Sites (7).

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

Polyostotic form: Femur, tibia, pelvis.

199

Fibrous dysplasia: Presentation.

Polyostotic form: Pain and recurrent fractures in childhood.

200

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

Skull: Facial deformities.

Long bones: Recurrent fractures with "shepherd's crook" deformity.

Ribs: Usually asymptomatic.

201

Fibrous dysplasia: Syndromes (3).

McCune-Albright.

Cherubism.

Mazabraud's.

202

McCune-Albright syndrome (4).

Fibrous dysplasia.

Precocious puberty.

Hyperthyroidism.

Café-au-lait macules ("coast of Maine").

203

Cherubism.

Fibrous dysplasia mainly affecting the jaws.

Many giant cells.

204

Mazabraud's syndrome.

Fibrous dysplasia.

Myxomas of soft tissue.

205

Fibrous dysplasia: Location in bone.

Intramedullary; diaphysis or metaphysis.

206

Fibrous dysplasia: Radiography.

Intramedullary mass causing cortical expansion.

207

Fibrous dysplasia: Locational variation.

Surface of bone: Fibrous dysplasia protuberans.

208

Fibrous dysplasia: Histology of trabeculae (3).

Resemble "Chinese letters".

No osteoblastic rimming.

Mineralization may form laminated structures that resemble cementoid bodies.

209

Fibrous dysplasia: Histology of stroma.

Consists of fibroblastic spindle cells in a storiform pattern.

210

Fibrous dysplasia: Histology of periphery.

Reactive bone with osteoblastic rimming.

211

Fibrous dysplasia: Histologic variation.

Foci of cartilaginous differentiation: Fibrocartilaginous dysplasia.

212

Fibrous dysplasia: Affected gene.

GNAS1.

213

Fibrous dysplasia: Complication.

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

214

Fibrous dysplasia vs. desmoplastic fibroma.

Desmoplastic fibroma: No woven bone.

215

Osteofibrous dysplasia: Synonym.

Ossifying fibroma of long bones.

216

Osteofibrous dysplasia: Age group.

Mostly children under the age of 5 years.

217

Osteofibrous dysplasia: Sites.

Anterior surface of tibia or of fibula.

218

Osteofibrous dysplasia: Histology (3).

Similar to that of fibrous dysplasia but with

- Osteoblastic rimming.
- Simpler shapes of trabeculae.
- Maturation of bone.

219

Osteofibrous dysplasia: Radiography.

Cortical; diaphysis.

220

Osteofibrous dysplasia vs. osteosarcoma.

Osteosarcoma: The stromal spindle cells show nuclear atypia.

221

Osteofibrous dysplasia: Complication.

No known malignant transformation.

222

Nonossifying fibroma: Synonyms (2).

Fibrous cortical defect.

Metaphyseal fibrous defect.

223

Nonossifying fibroma: Typical presentation.

Asymptomatic.

224

Nonossifying fibroma: Radiography.

Cortical; metaphyseal; lytic lesion with sclerotic margin.

225

Nonossifying fibroma: Histology (4).

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

Nonossifying fibroma vs. benign fibrous histiocytoma.

Benign fibrous histiocytoma:

- Identical histology.
- Term used when lesion occurs in ribs, vertebrae, or flat bones.

227

Nonossifying fibroma: Syndromes (2).

Neurofibromatosis.

Jaffe-Campanacci syndrome.

228

Desmoplastic fibroma: Sites.

Chin.

Pelvis.

Humerus.

Femur.

Tibia.

229

Desmoplastic fibroma: Histology.

Resembles a fibromatosis set among bony trabeculae.

230

Desmoplastic fibroma: Cytogenetics.

+8, +20.

231

Desmoplastic fibroma vs. low-grade fibrosarcoma.

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

232

Fibrosarcoma: Histology of grade 1 (3).

Bland fibroblasts.

No more than 4 mitotic figures per hpf.

Much collagen.

233

Fibrosarcoma: Histology of grade 2 (3).

More nuclear atypia.

More mitotic figures.

More cells; less collagen.

234

Fibrosarcoma: Histology of grade 3 (3).

Markedly atypical nuclei with large nucleoli.

Brisk mitotic activity, with atypical forms.

Necrosis, hemorrhage, myxoid change.

235

Fibrosarcoma: Mutation.

Gain of PDGFB at 22q12-q13.

236

Fibrosarcoma vs. desmoplastic fibroma (3).

Desmoplastic fibroma:

- Storiform rather than herringbone pattern.
- Contains tumor osteoid.
- No mitotic activity, no pleomorphism.

237

Fibrosarcoma: Most common antecedent.

Irradiation of a giant-cell tumor of bone.

238

Malignant fibrous histiocytoma: Iatrogenic antecedents (2).

Irradiation of bone.

Metallic prosthesis.

239

Malignant fibrous histiocytoma: Most common types seen in bone.

Storiform-pleomorphic.

Giant-cell-rich.

240

Malignant fibrous histiocytoma: Histologic pitfall.

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

241

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

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

242

Giant-cell tumor of bone: Age group.

Skeletally mature young adults.

243

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

Epiphyseal:

- Distal femur.
- Proximal tibia.
- Distal radius.
- Sacrum.

244

Giant-cell tumor of bone: Presentation.

Typical: Localized pain.

Sometimes: Pathologic fracture.

245

Giant-cell tumor of bone: Radiography

Lytic mass.

No sclerosis, no periosteal reaction.

Thin rim of bone separates expansile masses from soft tissue.

246

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

Bland, multinucleate, osteoclast-like giant cells.

Bland mononuclear cells in the background.

No cartilage unless there has been a fracture.

247

Giant-cell tumor of bone: Cytogenetics.

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

248

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

C-MYC.

The gene of hepatocyte-growth-factor receptor.

The gene of VEGF.

249

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

Giant-cell reparative granuloma:

- Giant cells are unevenly distributed.
- Giant cells have fewer nuclei.
- More fibrotic stroma.
- Stromal cells are spindle shaped.

250

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

Nonossifying fibroma:

- Usually metaphyseal.
- Peripheral sclerosis.

251

Giant-cell tumor of bone vs. brown tumor.

Brown tumor: Elevated serum calcium and PTH.

252

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

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

Malignant tumors can arise from benign tumors.