Flashcards in Bones & Joints Deck (253)
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Osteoma: Presentation.
May be asymptomatic.
May cause symptoms if involving sinuses or orbits.
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Osteoma: Radiography (3).
Radiodense.
Circumscribed; no destructive features.
Involves surface or medulla of bone.
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Osteoma: Behavior.
Rarely recurs.
No malignant transformation.
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Osteoma: Histology.
Dense lamellar bone.
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Osteoid osteoma: Age group.
Second and third decades.
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Osteoid osteoma: Sites (3).
Proximal femur.
Vertebrae.
Small bones of hands and feet.
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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.
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Osteoid osteoma: Radiography (2).
Cortical radiolucent nidus, usually less than 1 cm in diameter, surrounded by sclerosis.
Plain radiographs miss about 25% of tumors.
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Osteoid osteoma: Histology of nidus (3).
Interlacing trabeculae that are
- Variably mineralized.
- Rimmed by osteoblasts.
- Surrounded by fibrovascular stroma that contains multinucleate giant cells.
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Osteoid osteoma: Histology of periphery.
Fibrovascular tissue surrounded by compact lamellar bone.
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Osteoid osteoma: What should not be seen within the tumor (3).
Cartilage, unless there had been a fracture.
Marrow elements.
Fat.
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Osteoid osteoma: Preoperative aids to recognition.
Identification of the nidus may be facilitated by
- Tetracycline: Nidus becomes fluorescence in UV light.
- Tc-99m.
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Osteoid osteoma: Mutation.
Partial deletion of 22q in some cases.
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Osteoid osteoma: Immunohistochemistry.
Some cases express c-fos and c-jun.
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Osteoid osteoma vs. stress fracture.
Stress fracture:
- Dense, mature bone is in the center.
- Woven bone is in the periphery.
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Osteoid osteoma: Why painful (3)?
Unmyelinated axons in the nidus.
Production of prostaglandin E2.
Production of prostacyclin.
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Osteoblastoma: Age group.
Occurs mainly in the second and third decades.
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Osteoblastoma: Sites
Vertebral column and sacrum.
Mandible and other bones of the skull.
Extremities.
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Osteoblastoma:
A. Location in bone.
B. Presentation.
A. In the medulla.
B. Not as painful as osteoid osteoma.
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Osteoblastoma: Radiography (2).
Expansile radiolucent zone (nidus) with a sclerotic rim.
Nidus is more than 1.5 cm in diameter.
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Osteoblastoma: Variations on radiography (3).
Formation of new bone around tumor.
Cortical destruction that mimics osteosarcoma.
Secondary aneurysmal cyst.
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Osteoblastoma: Gross pathology (3).
Similar to that of osteoid osteoma, but osteoblastoma is larger.
Variations:
- Cortical thinning.
- Hemorrhagic (secondary aneurysmal) cyst.
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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.
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Osteoblastoma: Variations on histology (2).
Variable mineralization of osteoid.
Large blood lakes (secondary aneurysmal bone cysts).
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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.
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Bizarre osteoblastoma:
A. Synonym.
B. Histology.
A. Pseudo-malignant osteoblastoma.
B. Contains bizarre multinucleate giant cells without mitotic activity.
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Osteoblastoma vs. osteoblastic osteosarcoma
Osteoblastic osteosarcoma:
- Sarcomatoid stroma.
- Osteoblasts form sheets or aggregates rather than a rim.
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Conventional intramedullary osteosarcoma: Sites (3).
Metaphyseal:
- Distal femur.
- Proximal tibia.
- Proximal humerus.
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Conventional intramedullary osteosarcoma: Sites in Paget's disease (3).
Bones of the skull.
Ribs.
Vertebrae.
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