Congenital and Acquired Bone Path

Question 1

Brachydactyly Types D and E

Mutation and Phenotype Presentation (2)

Answer 1

HOXD13

Short
Broad terminal phalanges of first finger

Question 2

Cleidocranial dysplasia

Mutation and Phenotype Presentation (3)

Answer 2

RUNX2

Abnormal clavicles
Wormian bones (extra cranial bones)
Supernumerary teeth

Question 3

Achondroplasia

Mutation and Phenotype Presentation (4)

Answer 3

Autosomal dominant FGFR3 gain of function

Short with short limbs
Frontal bossing
Depressed nose
Normal trunk length

Question 4

Thanatophoric Dysplasia

Mutation and Phenotype Presentation (3) Prognosis

Answer 4

FGFR3 gain of function

Macrocephaly
Bell shaped abdomen
Small Chest Cavity

Die from respiratory insufficiency

Question 5

Osteogenesis Imperfecta
Mutation, Presentations
Type I (4) Type II (1) Type III (4) Type IV (3)

Answer 5

COL1A1/COL1A2 defect

Type I
Blue sclera
Loose joints
Normal lifespan and collagen structure
Brittle teeth
Hearing loss

Type II
Death in utero (respiratory problems)

Type III
Blue sclera
Severe joint deformity
Spinal curvature
Barrel shaped ribs

Type IV
White sclera
Spinal curvature
Barrel shaped ribs

Question 6

Osteopetrosis

Mutation (2) Morphology (2) Clinical Presentation (5)

Answer 6

CLCN7 mutation
Carbonic Anhydrase 2 (CA2) deficiency

Bones lack medullary cavity
Erlenmeyer flask bulbous bones

Deafness*
Anemia*
Optic atrophy
Facial paralysis
Repeated fractures

Question 7

Osteopenia vs Osteoporosis Criteria

Answer 7

Osteopenia
Decreased bone mass 1-2.5 standard deviations below

Osteoporosis
Decreased bones mass 2.5+ standard deviations below

Question 8

Osteoporosis
Pathologic Categories (5) with Descriptions
Age (2) Physical, Genetic, Nutrition (2) Hormones (3)

Answer 8

Age Related:
Decreased proliferation and biosynthesis
Low turnover variant

Decreased Physical Activity:
Decreased load on bones decreases bone density

Genetic: LRP5 gene defect

Calcium Nutritional State:
Decreased intake in adolescence and young adulthood causes sub-maximal bone density
Particular issue with anorexic teenagers

Hormonal Influence:
Accelerated bone loss post-menopause (high turnover variant)
Decreased estrogen increases Resorption > Formation
Tamoxifen (breast cancer Tx) can cause osteoporosis

Question 9

Osteoporosis
Pathognomonic Presentation (1) Morphology (3) Risk Factors (3) Secondary Causes (3)

Answer 9

Vertebral compression fracture

Cancellous bone (increased surface area)
Thinned trabeculae
Subperiosteal/Endosteal bone resorption (in senile OP)

Caucasian
Excess Phosphorous intake
Smoking

Renal/Hepatic Failure
Hyperthyroidism
Hyperparathyroidism

Question 10

Paget Disease (osteitis deformans)
Locations (2) Morphology Hallmarks (3) and Phases (3)

Answer 10

Axial Skeleton
Femur

Mosaic pattern of lamellar bone (phase 3)
Jigsaw-like with prominent cement lines
Cotton wool cranium appearance

Phases:

1) Lytic - large osteoclasts with 100 nuclei
2) Mixed - OC’s and Osteoblasts present
3) Osteosclerotic - mosaic lamellar bone

Question 11

Paget Disease

Pathogenesis (2) Presentation (4) Lab Values (3) Associated Tumors (2)

Answer 11

Mostly Familial
Sporadic: SQSTM1 mutation

Bowed legs
Chalk-stick LE Fx
Compression Fx of spine: kyphoscoliosis
Hypervascularity: warm skin

Elevated Alk-Phos
Normal Calcium
Normal Phosphorous

Osteosarcoma
Fibrosarcoma

Question 12

Hyperparathyroidism
Complications (4)

Answer 12

Osteoporosis

Dissecting osteitis: railroad track trabeculae

Brown tumor

Osteitis fibrosis cystica (von Recklinghausen)

Question 13

Renal Osteodystrophy

Pathogenesis (4) and Clinical Features (4)

Answer 13

Acidosis dissolves hydroxyapatite
Decreased phosphate excretion
Increased calcium excretion
Decreased Vit D synthesis

Osteopenia/osteoporosis
Osteomalacia
Secondary hyperparathyroidism
Growth retardation

Question 14

Fracture Definitions

Simple, Compound, Comminuted, Displaced, Stress, Greenstick (2) Pathologic

Answer 14

Simple: overlying skin intact

Compound: bone communicates with skin surface

Comminuted: fragmented bone

Displaced: ends of bone not aligned

Stress: slow developing, from repetitive loads

Greenstick: partial fracture, common in babies

Pathologic: bone weakened by underlying disease

Question 15

Osteonecrosis

Causes (2) Complications (2) Morphology (3)

Answer 15

Long term corticosteroid use
Fracture

Subchondral infarcts
Medullary infarcts: trabecullar bone and marrow

Wedge shaped infarcts
Creeping substitution of trabecular scaffold
Cartilage sloughing

Question 16

Pyogenic Osteomyelitis
Etiologies (4) with Populations
Infections Routes: Kids (1) Adults (2)

Answer 16

Staphylococcus aureus: most common

E. coli, Pseudomonas, Klebsiella:
Patients with UTI’s or IV Drug Users

Salmonella: Sickle cell patients

Neisseria: MAC deficiency patients

Kids: hematogenous spread from mucosa
Adults: Open fractures, diabetic foot sores

Question 17

Pyogenic Osteomyelitis Stages with Descriptions

Acute (3) and Chronic (2)

Answer 17

Acute: 48 hours
Subperiosteal abscesses
Sequestrum: dead bone after abscess
Infants at risk of septic arthritis

Chronic: after 1 week
Involucrum: shell of living tissue of new bone
Brodie Abscess: Interosseous abscess, walled off by reactive bone

Question 18

Mycobacterial Osteomyelitis
Symptoms (2) Histology
Main Complication with Description (2)

Answer 18

Low grade fevers
Weight loss

Caseating necrosis and granulomas

Tuberculous Spondylitis:
Permanent compression fractures of the spine
“Potts Disease”

Question 19

Skeletal Syphilis Presentations

Congenital and Acquired

Answer 19

Congenital
Saber shins

Acquired Tertiary
Saddle Nose