Bone Pathology Duval

Question 1

What is a major cause of dwarfism?

Answer 1

Achondroplasia

Question 2

What is the MC congenital disorder of the growth plate?

Answer 2

Achondroplasia

Question 3

Achondroplasia genetic factor

Answer 3

Only 20% have family history, so 80% of cases are sporadic mutations

Question 4

Pathophys of achondroplasia

Answer 4

• Impaired maturation of cartilage in the growth plate
• Hypoplastic disorganized chondrocyte aggregations
• Affects all bones that form from cartilage (endochondral formation)

Question 5

Pathophys of osteogenesis imperfecta

Answer 5

Abnormal development of type I collagen

Question 6

Describe osteopetrosis (pathology)

Answer 6

• Group of rare genetic disorders (4 variants)

- Reduced osteoclast mediate bone resorption resulting in defective bone remodelling (dense stone-like bone)

Question 7

Describe osteoporosis (pathology)

Answer 7

• Increase in bone fragility due to a reduction in bone mass

- Localized or generalized

Question 8

What causes age related bone loss? (pathology)

Answer 8

Decreased osteoblast activity

Question 9

Morphology of osteoporosis

Answer 9

• Affects vertebral bodies, femoral neck
• Thin, widely separated bony trabeculae
• Normal mineral content though
• Normal osteoclast activity

Question 10

How does hyperPTH affect bones?

Answer 10

• Increases serum Ca
• Activates osteoclasts
• Excessive osteoclastic activity

Question 11

Morphology of hyperPTH (pathology)?

Answer 11

• Increased osteoclast activity (bone erosion)
• Reduced cortical bone and increased loose CT
• Hemosiderin deposits from previous fractures
• Brown tumor (hemosiderin, osteoclasts clump)

Question 12

What factors can disrupt fracture repair? (pathology)

Answer 12

• Delayed healing from needing extensive remodeling (displaced/comminuted fx)
• Delayed union or non-union (from inadequate immobilization)
• Pseudarthrosis (false joint from non-union)
• Infection
• Health status (comorbidities)

Question 13

Morphology of osteonecrosis (pathology)

Answer 13

• Dead bone w/empty lacunae, fat necrosis, Ca soaps
• Cortical bone and articular cartilage spared
• Necrotic bone acts as scaffold for new bone

Question 14

MC organisms causing pyogenic osteomyelitis

Answer 14

• S aureus
• E coli, group B strep (neonates)
• Salmonella (sickle cell)
• Mixed flora (trauma)

Question 15

What is Brodie’s abscess?

Answer 15

• Formed in chronic pyogenic osteomyelitis
• Residual necrotic bone (sequestrum)
• Surrounding reactive bone (involucrum)

Question 16

Pathology of TB osteomyelitis: what areas affected?

Answer 16

• Synovium/epiphyses of long bones

- Vertebrae (Pott’s disease, psoas abscess)

Question 17

Paget’s disease of bone (pathology)

Answer 17

• Skeletal deformities d/t intermittent exuberant osteoclast/blast activity
• Uncommon under 40 yo
• Males mainly

Question 18

Pathogenesis of Paget’s disease

Answer 18

• Paramyxovirus-like particle in osteoclasts
• Cytokine induced osteoclast activation
• Hyper responsive osteoclasts

Question 19

Morphologic phases of Paget’s disease

Answer 19

• Osteoclastic/lytic phase
• Mixed proliferation
• Osteosclerotic “jigsaw puzzle”

Question 20

Which cancers MC metastasize to bone?

Answer 20

Prostate, breast, lung

Question 21

What is the MC type of bone tumor?

Answer 21

Mets from a primary tumor

Question 22

What are primary tumors of the bone?

Answer 22

• Osteoma
• Osteoblastoma
• Osteosarcoma (malignant)

Question 23

Osteoma features (pathology)

Answer 23

• Head and neck
• Localized, solitary
• No malignant transformation

Question 24

Osteoid osteoma/osteoblastoma features (pathology)

Answer 24

• Femur, tibia/vertebrae
• Young adult males
• Circumscribed, cortex

Question 25

What is the MC malignant primary bone tumor?

Answer 25

Osteosarcoma

Question 26

Classic features of osteosarcoma (pathology)

Answer 26

- Adolescent males - Distal femur, proximal tibia - Sporadic or hereditary mutation

Question 27

Morphology of classic osteosarcoma

Answer 27

- Large, ill-defined - Destructive - Elevates periosteum (Codman's triangle) - Islands of primitive bony trabeculae (osteoid) rimmed by malignant osteoblasts

Question 28

Describe osteochondroma (pathology)

Answer 28

- Cartilagenous tumor - Mature bone w/cartilagenous cap - Metaphysis of long bones

Question 29

Describe chondroma (pathology)

Answer 29

- Benign proliferation of mature hyaline cartilage - Small bones of hands, feet - Young to middle aged adults

Question 30

Describe chondrosarcoma (pathology)

Answer 30

- Older males, axial skeleton - 2nd MC malignant bone tumor - Glistening expansile mass in medullary cavity eroding cortex

Question 31

Describe giant cell tumor of bone (pathology)

Answer 31

- Benign - Proliferation of reactive osteoclast-like giant cells - Young to middle aged females - Epiphysis of long bones

Question 32

Morphology of giant cell tumor of bone (gross vs. micro)

Answer 32

- Gross: solitary, dark brown (vascular), necrotic, cystic | - Micro: 2 cell types (MNGC, mononuclear)

Question 33

Describe Ewing sarcoma (pathology)

Answer 33

- Highly aggressive tumor of children/adolescents - Chromosomal translocation - Diaphysis of femur, tibia, pelvis

Question 34

Describe fibrous dysplasia (pathology)

Answer 34

- Uncommon, benign, tumor-like | - MC type is monostotic (70%)

Question 35

McCune Albright syndrome (pathology)

Answer 35

- Part of syndrome is fibrous dysplasia - Unilateral bone lesions - Ipsilateral cafe au lait spots - Precocious puberty

Question 36

Morphology of fibrous dysplasia

Answer 36

- Circumscribed, radiolucent, sclerotic rim | - Trabecular bone replaced by fibrous tissue w/disorderly islands of malformed woven bone

Question 37

What type of benign tumor can transform to malignant?

Answer 37

Giant cell tumor of the bone