USMLE pretest questionnaire solutions

1. Submitted by:-
Anubhuti Dave
Group 21

2. 447. A young boy is being evaluated for a history of numerous fractures in
the past. These fractures have resulted from minimal trauma. Examination
of his peripheral blood reveals leukoerythroblastosis with numerous target
cells. Which one of the following abnormalities is most characteristic of
this boy’s disease process?
a. Abnormal “tunneling” of osteoclasts into bone trabeculae
b. Abnormal osteoclasts that lack the normal ruffled border
c. Decreased calcification of osteoid matrix
d. Decreased cartilage cell proliferation at epiphyseal plates of long bones
e. Defective synthesis of type I procollagen

3. a. Abnormal “tunneling” of osteoclasts into bone trabeculae
Renal osteodystrophy, is caused by increase in parathyroid hormone secretion
the above mentioned abnormality is a sign of this disease.
It occurs in end stage renal disease in patient on long-term haemodialysis.
There is decreased osteoclastic resorption by the bones resulting in low level of
Ionized calcium.
Resorption is revealed by deep scallopin deffects containing numerous large
Osteoclasts, which causes tunneling of osteoclasts into bone trabeculaue.

6. b. Abnormal osteoclasts that lack the normal ruffled border>>>ANSWER
Osteopetrosis (marble bone disease) is a rare inherited disease
characterized by abnormal osteoclasts that histologically lack the
usual ruffled borders,
LeukoerythroBlastosis: Osteopetrosis causes Myelophthisic Anemia in which
immature elements are forced into peripheral blood, resulting in
LEUKOERYTHROBLASTIC SMEAR

7. The end result
is a sold bone
with no
marrow cavity
Hence the
common name
for the
condition,
marble bone
disease

8. Typical
cranial
deformity
and
thoracic
scoliosis

9. c. Decreased calcification of osteoid matrix
Several diseases can result in disorders of bone mineralization in children,
including rickets, renal diseases (renal osteodystrophy, Fanconi syndrome etc.
These conditions may result in failure of osteoid calcification (rickets) in children
because of a disruption in the pathway of either vitamin D or phosphate
metabolism.

11. d. Decreased cartilage cell proliferation at epiphyseal plates of long bones
The most common defect is achondroplasia, where there is a defect in cartilage formation.
Achondroplasia is the most common cause of dwarfism.

12. e. Defective synthesis of type I procollagen
Osteogenesis imperfecta (OI), also known as brittle bone disease
Type II Collagen is not of a sufficient quality or quantity.
Type II can be further subclassified into groups A, B, and C
Type IIA demonstrates broad and short long bones with broad and beaded ribs.
Type IIB demonstrates broad and short long bones with thin ribs that have little or no
beading.
Type IIC demonstrates thin and longer long bones with thin and beaded ribs.

13. Characteristically
blue sclerae of
patient with
osteogenesis
imperfecta

14. Osteogenesis imperfecta with
tibial deformities

15. 448. A 4-year-old boy presents with a history of numerous fractures that
are not related to excessive trauma. Physical examination reveals evidence
of previous fractures along with abnormally loose joints, decreased hearing,
and blue scleras. X-rays of the boy’s arms reveal the bones to be
markedly thinned. What is the correct diagnosis?
a. Osteopetrosis
b. Osteoporosis
c. Osteomalacia
d. Osteogenesis imperfecta
e. Osteitis deformans

16. Osteoporosis
Around the world, 1 in 3 women and 1 in 5 men are at risk of an osteoporotic fracture.
In fact, an osteoporotic fracture is estimated to occur every 3 seconds. The most
common fractures associated with osteoporosis occur at the hip, spine and wrist.
The likelihood of these fractures occurring, particularly at the hip and spine,
increases with age in both women and men.
Concern are vertebral (spinal) and hip fractures. Vertebral fractures can result in
serious consequences, including loss of height, intense back pain and
deformity (sometimes called Dowager's Hump). A hip fracture often requires
surgery and may result in loss of independence or death.

18. Osteoporotic vertebral bodies: gross
anatomy

19. Osteomalacia
Osteomalacia refers to a softening of your bones, often caused by a vitamin D deficiency.
Soft bones are more likely to bow.
Muscle weakness and achy bone pain are the major symptoms of osteomalacia.
Bones that have softened due to osteomalacia have a normal amount of collagen, which
gives structure to the bones. However, the bones lack the proper amount of calcium to
keep them hard.
Symptoms
Bone fractures that happen without a real injury
Muscle weakness
Widespread bone pain, especially in the hips

21. Osteitis deformans
Paget's disease is a chronic inflammatory progressive skeletal disorder mainly
occurring after the age of 40. Men are more frequently affected than women. It is
characterised by increased bone remodelling weakening the bone structure with
enlargement and deformities of the affected bones.
Clinical symptoms: headache, bowing and shortening of the legs, the arms appear
relatively long, enlargement of the head (hat and dentures no longer fit), and in
extreme cases a leontine facies develops (leontiasis ossea). The patient's overall
stature becomes smaller and monkey-like.

23. Paget’s Disease

24. The answer is d. Osteogenesis imperfecta>> already explained
Osteogenesis imperfecta.
The major variant of OI, type I, is compatible with survival; after the perinatal
period fractures occur in addition to other signs of defective collagen synthesis
such as thin, translucent, blue scleras; laxity of joint ligaments; deafness from
otosclerosis; and abnormal teeth.

25. 449. A 71-year-old female presents with the sudden onset of severe lower
back pain. Physical examination reveals severe kyphosis, while an x-ray of
her back reveals a compression fracture of a vertebral body in the lumbar
area along with marked thinning of the bones. Serum calcium, phosphorus,
alkaline phosphatase, and parathyroid hormone levels are all within
normal limits. This woman’s bone changes are most likely due to
a. Osteopetrosis
b. Osteoporosis
c. Osteomalacia
d. Osteitis fibrosa cystica
e. Osteitis deformans

26. Osteitis fibrosa cystica
Osteitis fibrosa cystica describes the advanced bony changes seen in patients with
primary or secondary hyperparathyroidism.
Osteitis fibrosa cystica is characterised by:
>extensive bone resorption accompanies marrow fibrosis with the
development of cysts within the enlarged fibrotic marrow spaces
>brown tumours
Skeletal changes are most prominent at the sites of highest bone activity -
trabecular bones of vertebrae, phalanges, the ends of long bones, and parts
of the skull.

27. Osteitis Fibrosa Cystica Brown
Tumor

28. Osteitis Fibrosa Cystica

29. The answer is b. Osteoporosis >>> already explained
Primary osteoporosis, the most common type of
osteoporosis, occurs most often in postmenopausal women and has been
related to decreased estrogen levels.
Osteoporosis predisposes patients to fractures
of weight-bearing bones, such as the femurs and vertebral bodies.