Bones & Joints Flashcards
1
Q
Osteoma: Presentation.
A
May be asymptomatic.
May cause symptoms if involving sinuses or orbits.
2
Q
Osteoma: Radiography (3).
A
Radiodense.
Circumscribed; no destructive features.
Involves surface or medulla of bone.
3
Q
Osteoma: Behavior.
A
Rarely recurs.
No malignant transformation.
4
Q
Osteoma: Histology.
A
Dense lamellar bone.
5
Q
Osteoid osteoma: Age group.
A
Second and third decades.
6
Q
Osteoid osteoma: Sites (3).
A
Proximal femur.
Vertebrae.
Small bones of hands and feet.
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.
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.
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.
10
Q
Osteoid osteoma: Histology of periphery.
A
Fibrovascular tissue surrounded by compact lamellar bone.
11
Q
Osteoid osteoma: What should not be seen within the tumor (3).
A
Cartilage, unless there had been a fracture.
Marrow elements.
Fat.
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.
13
Q
Osteoid osteoma: Mutation.
A
Partial deletion of 22q in some cases.
14
Q
Osteoid osteoma: Immunohistochemistry.
A
Some cases express c-fos and c-jun.
15
Q
Osteoid osteoma vs. stress fracture.
A
Stress fracture:
- Dense, mature bone is in the center.
- Woven bone is in the periphery.
16
Q
Osteoid osteoma: Why painful (3)?
A
Unmyelinated axons in the nidus.
Production of prostaglandin E2.
Production of prostacyclin.
17
Q
Osteoblastoma: Age group.
A
Occurs mainly in the second and third decades.
18
Q
Osteoblastoma: Sites
A
Vertebral column and sacrum.
Mandible and other bones of the skull.
Extremities.
19
Q
Osteoblastoma:
A. Location in bone.
B. Presentation.
A
A. In the medulla.
B. Not as painful as osteoid osteoma.
20
Q
Osteoblastoma: Radiography (2).
A
Expansile radiolucent zone (nidus) with a sclerotic rim.
Nidus is more than 1.5 cm in diameter.
21
Q
Osteoblastoma: Variations on radiography (3).
A
Formation of new bone around tumor.
Cortical destruction that mimics osteosarcoma.
Secondary aneurysmal cyst.
22
Q
Osteoblastoma: Gross pathology (3).
A
Similar to that of osteoid osteoma, but osteoblastoma is larger.
Variations:
- Cortical thinning.
- Hemorrhagic (secondary aneurysmal) cyst.
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.
24
Q
Osteoblastoma: Variations on histology (2).
A
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
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.
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Epithelioid hemangioendothelioma vs. cartilaginous tumor.
The chondroid-like matrix of epithelioid hemangioendothelioma do not express S100 and may express vascular markers.
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Solitary fibrous tumor: Sites (2).
Axial skeleton.
Lower extremities.
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Solitary fibrous tumor: Histology.
Solid proliferation of spindle cells surrounding staghorn vessels.
Variable mitotic activity, nuclear atypia, necrosis.
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Solitary fibrous tumor: Best predictor of malignancy.
Presence of more than 4 mitotic figures per 10 hpf.
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Solitary fibrous tumor: Immunohistochemistry (2,2).
Positive: CD34, STAT6.
Negative: CD99, vimentin.
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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.
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Solitary fibrous tumor: Differential diagnosis (6).
Metastatic solitary fibrous tumor.
Mesenchymal chondrosarcoma.
MFH.
Angioblastic meningioma.
Small-cell osteosarcoma.
Synovial sarcoma.
GIST.
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Hemangioma of bone: Immunohistochemistry (4).
Positive: CD31, CD34, factor VIII, ERG.
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Angiosarcoma: Associations (3).
Previous infarct of bone.
Chronic osteomyelitis.
Irradiation.
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Fibrous dysplasia: Sites (7).
Monostotic form (90%): Skull, femur, tibia, ribs.
Polyostotic form: Femur, tibia, pelvis.
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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.
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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.
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Fibrous dysplasia: Location in bone.
Intramedullary; diaphysis or metaphysis.
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Fibrous dysplasia: Radiography.
Intramedullary mass causing cortical expansion.
207
Fibrous dysplasia: Locational variation.
Surface of bone: Fibrous dysplasia protuberans.
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Fibrous dysplasia: Histology of trabeculae (3).
Resemble "Chinese letters".
No osteoblastic rimming.
Mineralization may form laminated structures that resemble cementoid bodies.
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Fibrous dysplasia: Histology of stroma.
Consists of fibroblastic spindle cells in a storiform pattern.
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Fibrous dysplasia: Histology of periphery.
Reactive bone with osteoblastic rimming.
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Fibrous dysplasia: Histologic variation.
Foci of cartilaginous differentiation: Fibrocartilaginous dysplasia.
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Fibrous dysplasia: Affected gene.
GNAS1.
213
Fibrous dysplasia: Complication.
Fibrosarcoma, osteosarcoma, chondrosarcoma, or MFH may arise from it.
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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.
253
Osteoma: Sites.
Bones of the skull.
