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Anatomic pathology > Bones & Joints > Flashcards

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

Periosteal chondroma vs. periosteal osteosarcoma (2).

Periosteal osteosarcoma:

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