Flashcards in Bones & Joints Deck (253)
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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
