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Orthopaedics > Pathology - Tumours > Flashcards

Pathology - Tumours Flashcards

1
Q

What is an Osteochondroma/Exostosis

A

Bony Outgrowth capped by a cartilage cap, attached to the underlying skeleton by a bony stalk

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2
Q

Where do Exostoses occur?

A

Metaphyses near the growth plate of long tubular bones near the knee, pelvis, scapula and ribs

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3
Q

What is the ratio of exostoses cases that are solitary outgrowths

A

85%

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4
Q

When does exostoses occur most commonly?

A

First 2 decades

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5
Q

If malignant, what does exostoses lead to?

A

chondrosarcoma

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6
Q

What is the pathophysiology of exostosis?

A

EXT1 & EXT2 genes mutated which code for enzymes to make heparan sulfate glycosaminoglycans = decrease diffusion of IHH which regulates cartilage growth

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7
Q

State a factor that increases malignant transformation of exostoses

A

Multiple Outgrowths: Multiple Hereditary Exostoses Syndrome (bones may be bowed or shortened)

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8
Q

What is the morphology of exostoses cases?

A

Sessile, Pedunculated, 1-20cm, cap made of hyaline cartilage and covered in perichondrium

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9
Q

What is the histologic appearance of Exostoses?

A

Disorganised growth plate; undergoes Endochondral ossification (newly made bone forms inner portion of head and stalk

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10
Q

What are morphological features of chondromas?

A
  1. Well Defined
  2. No soft tissue invasion
  3. Calcification - stippled, flocculent
  4. Bulbous Expansions
  5. Complications: Fractures, Malignant Degeneration
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11
Q

What are histological features of chondromas?

A
  1. Mature Hyaline Cartilage (Gray-blue/translucent)
  2. No Cytological Atypia
  3. No permeation of bone trabeculae or marrow
  4. No Soft Tissue Invasion
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12
Q

What is the morphology of a simple bone cyst?

A

Cyst-like structure with fibrous wall
Amorphous pink material with a cementum-like appearance

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13
Q

What is the molecular mutation of a Simple Bone Cyst?

A

FUS or EWSR-1-NFATC2 fusion

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14
Q

What are the clinical features of a simple bone cyst?

A
  1. Benign, Fluid Containing Lesion
  2. Occurs in metaphyses
  3. 50% present as pathological fracture
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15
Q

Most common occurence of simple bone cysts?

A

4-10 years old

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16
Q

What is an osteoid osteoma?

A

Benign bone-forming tumour characterised by extensive reaction and pain disproportionate to size

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17
Q

Clinical features of osteoid osteoma?

A
  1. pain becomes unrelenting when untreated
  2. nidus in bone
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18
Q

Locations of Osteoid Osteoma?

A

Cortical Diaphyseal (65%-70%)
Femur > Tibia
Intracapsular (esp femoral neck)
Spine (10%, usually posterior elements)

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19
Q

EpiD of osteoid osteoma?

A
  1. 10-25 years old
  2. M:F = 3:1
  3. 4% of primary tumours
  4. Rarely malignant change to osteogenic sarcoma
  5. 20% recurrence
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20
Q

Treatment of Osteoid Osteoma & Osteoblastoma?

A

OO: Aspirin, NSAIDS, radiofrequency ablation
OB: Curettage followed by bone grafting

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21
Q

Imaging of Osteoid Osteoma?

A
  1. Oval Lytic Lesion (loosened lesion) in cortical bone; rounded; sclerosis
  2. Sclerosis may obscure underlying lytic nidus on radiograph
  3. Calcified nidus and cortical sclerosis (thickening) on CT
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22
Q

Distinguish between Osteoid Osteoma and Osteoblastoma?

A

Thick rim of reactive cortical bone

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23
Q

Features of Osteoblastoma?

A

Anastomosing woven bone trabaculae rimmed by abundant osteoblasts
Loose and vascular intrabacecular spaces
No malignant features (atypia, invasion, maligant osteoid)

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24
Q

What age does osteosarcomas occur?

A

10-25

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25
Q

How do osteosarcomas present?

A

Soft Tissue Swelling & Intermittent Pain
Pathological Fracture (15%)

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26
Q

Where and how do osteosarcomas metastasise to?

A

Lungs, Liver via hematogenous spread

27
Q

Where are sites of origin of osteosarcomas?

A

Metaphyses of long bones (distal femur, proximal tibia, proximal humerus)
Arises within the meduallary cavity and extends to cortex

28
Q

What radiological sign is an indicator of aggresive osteosarcoma

A

Triangular Shadow between cortex and raised periosteal ends (Codman Triangle)

29
Q

What is a diagnostic radiological sign of osteosarcoma?

A

Sunburst periosteal reaction - tumour breaks through the cortex & lifts the periosteum

30
Q

What type of lesion is osteosarcoma?

A

Sclerotic, lytic or mixed

31
Q

What mutations are involved in osteosarcoma?

A
  1. R13
  2. P53
  3. CDKN2A (encodes tumour suppressors p16 & p14)
  4. MDM2 & CDK4 overexpressed (function to inhibits p53 and R13)
32
Q

What are the histological features of osteosarcoma?

A
  1. Malignant Tumour Cells - Pleomorphic, Atypia, Hyperchromatic Nuclei, Abundant Mitoses
  2. Maligant Osteoid Pattern (lace-like pattern of osteoid: tumour cells produce unmineralised osteoid that becomes mineralised bone)
  3. Invasive Growth Pattern - intravascular patten
  4. Tumour necrosis, hemorrhage, cystic degeneration
33
Q

Fun Facts about Osteosarcoma

A
  1. Bulky gray white tumours
  2. Tumour cells can also form broad sheets or primitive trabeculae
  3. Neoplastic cells can also produce cartilage; if abundant = chondroblastic osteosarcoma
  4. Tumour destroys surrounding cortices to produce soft tissue masses that spread extensively in the medullary cavity & replace marrow
  5. May penetrate epiphyseal plate or enter joint - grow along tendoligamentous structure or through attachment site of joint capsule
34
Q

When do chondrosarcomas occur?

A

4th to 6th decade

35
Q

Where does chondrosarcomas occur?

A

Long bones, pelvis, ribs, spine (<10%)

36
Q

What are features of chondrosarcomas

A
  1. Metaphyseal
  2. Lucent, Expanded
  3. Ill-defined margins
  4. Calcium, amorphous, Calcification
  5. Cortical Destruction
37
Q

What is a chondrosarcoma?

A

A Malignant bone tumour that produces cartilage (but not osteoid)

38
Q

What are the macroscopic features of chondrosarcoma?

A
  1. Large lobulated tumour with pearly white or light blue, often with focal calcification
  2. Locally aggressive tumour that invades surrounding bone and soft tissue
39
Q

What are histological features of chondrosarcomas?

A
  1. Malignant tumour that produces cartilaginous matrix
  2. Cytological atypia
  3. Permeation of bone trabaculae
  4. Soft tissue and marrow invasion
40
Q

How do chondrosarcomas present?

A

Presents as painful, progressively enlarging mass

41
Q

Radiographic features of chondrosarcoma?

A
  1. Ill-defined bone destruction
  2. Adjacent some tissue swelling
  3. Calcification
  4. Foci of flocculent densities
42
Q

What are the two types of chondrosarcomas and their features?

A
  1. Slow growing, low grade: Reactive cortical thickening
  2. Aggresive, High grade: Destroy cortex, form soft tissue masses
43
Q

EpiD of chondrosarcoma

A

15% are secondary - arise from enchondromas or osteochondromas
- EXT, IDH1/2, CDKN2A gene silenccing by DNA methylation

44
Q

Grading of Chondrosarcomas?

A

Based on cellularity & nuclear changes in chondrocytes
- well to poorly differentiated correspond to grades 1-3: high grade = locally aggressive + mets to lungs

45
Q

Spread of chondrosarcomas?

A

Hematogenously

46
Q

Treatment of chondrosarcomas?

A

Surgical excision, (for severe use adjuvant chemotherapy)

47
Q

Age of Ewing’s Sarcoma?

A

5-20 years old

48
Q

Male Female Ratio of Ewing’s Sarcoma?

A

61M-39F

49
Q

Sites of Ewing’s Sarcoma?

A

Femur, Tibia, Fibula, Humerus, Ribs, Clavicle, Pelvis

50
Q

Symptoms of Ewing’s Sarcoma?

A

Pain, enlarging mass, tender, warm, swollen

51
Q

Pathophysiology of Ewing’s Sarcoma?

A

Translocation t(11,22)

52
Q

Diagnostic tests for Ewing’s Sarcoma?

A

FISH or RT-PCR

53
Q

Radiological Features of Ewing’s Sarcoma?

A
  1. Destructive lytic tumour with permeative, moth eaten margins extending into soft tissue
  2. ‘Onion skin’ periosteal reaction
  3. Ill-defined destruction of bone that is diaphyseal in location
54
Q

Histological features of Ewing’s Sarcoma?

A
  1. Small, rounded cells with scant clear cytoplasm
  2. Homer-wright rosettes (central fibrillary space)
  3. Positive IHC stains: CD99
  4. Glycogen material
55
Q

DDx of Ewing’s Sarcoma?

A
  1. Osteomyelitis
  2. Lymphoma
  3. rhabdosarcoma
  4. neuroblastoma
  5. small cell carcinoma
56
Q

What imaging modalities are used for bone tumours/mets?

A
  1. MRI
  2. Bone Scan - may show lesions throughout
  3. Plain film - useful for pt with known mets that may present w bone pain or suspected pathological fracture
57
Q

Method of spread of mets to bone?

A
  1. Direct extension
  2. Lymphatic/hematogenous
  3. Intraspinal seeding (Batson plexus of veins)
58
Q

Common location of mets to bone?

A

axial skeleton (vertebral column, pelvis, ribs, skull, sternum) in which marrow has a rich capillary network

59
Q

Focality of mets to bone

A

Multifocal; kidney and thyroid are solitary

60
Q

EpiD of Mets to bone

A

75% from prostate, breast, kidney lung
In children, neuroblastima, Wilm’s tumour, osteosarcoma, Ewing’s Sarcoma, Rhabdosarcoma

61
Q

Effects of Mets

A
  1. Lytic - kidney, lung, GI, malignant melanoma
  2. Blastic - prostatic adenocarcinoma
62
Q

Changes in bone matrix in mets

A
  1. Tumour cells: PGs, cytokines, PTHrP = upregulate RANKL in osteoblasts and stromal cells = increase osteoclastic activity
  2. Tumour cells: release matrix bound growth factors (TGF- beta, IGF-1, FGF) = support tumour cell growth
  3. Sclerotic mets: due to tumour cells secreting WNT proteins that stimulate osteoblastic bone formation
63
Q

Treatment for mets

A
  1. Symptomatic relief
  2. Systemic, chemo, immunotherapy, localised radiation & bisphosphonates
  3. Surgery to stabilise fractures (esp in spinal mets)

Orthopaedics (6 decks)

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