Skeletal Dysplasia

Question 1

Diagnosis is by?

Answer 1

Radiology

Disproportionate features are suspicious for skeletal dysplasia

Size of the head, ratio of the upper to lower body and the segments of each part

If arm span is more than height…suspect

In children skeletal development is gradual…so must keep that in mind

Question 2

Acromelic dysplasia

Answer 2

Ends of extremities (hands and feet) are abnormal —> decreased arm span

Malformed phalanges (bullet shaped)…

Distal phalanges could be hypoplastic

Also could have an extra digit

Question 3

Mesomelic dysplasia

Answer 3

Middle parts of the extremities are shortened (forearm)

Question 4

Rhizomelic dysplasia

Answer 4

Shortened proximal extremity

Humerus and femur are shortened

Question 5

Things to consider when diagnosing

Answer 5

It is the primary or secondary problem?

If CNS issues are present —> consider chromosomal or metabolic abnormalities

If the disease is progressive (gets worse over time) consider lysosomal storage disease and peroxisomal diseases

Question 6

MPS (clinical)

Answer 6

Will progress and the child will have significant facial changes and changes to skeletal features

BMT does help to slow the CNS progression of the disease … as well as imporving liver and heart functino and sleep problems

But it does not do anything to help the bone disease

Question 7

Rhizomelic chondrodysplasia punctata

Answer 7

= peroxisomal disorder…significant progression of symptoms

Dysmorphic facies

Congenital cataracts, hypotonia

Skeletal abnormalities

Severe growth and development delays

“Metaphyseal flaring” = narrowing of the diaphysis and widening of the metaphysis

Epiphyseal stippling = multiple ossification centers giving a spotted appearance

Small thorax,

Vertebral coronal clefts (radiolucent vertical defect on a lateral XR)

Mineralization of IVDs

Prone to resp. And cardia complications

Reduced lifespan and usually die before 10 years

Question 8

Achondroplasia

Answer 8

AD disorder - most of the time they are new mutations
—> 98% have a G1128A substitution in FGFR3 (fibroblast growth factor receptor3)
—> two AD mutations = lethal
Therefore two migits have a 1/3 chance of having a healthy kid

Disproportionate short stature with normal IQ

Rhizomelic shortening and redundant skin folds

Trident hands

Bow legs

Thoracolumbar gibbus in infancy = sharp angle in the lower back

Get lumbar lordosis once walking

Frontal bossing (prominent forehead)

Large head

Question 9

OI

Answer 9

Weak and easily breakable bones

CT disease caused by defects in collagen production

Therefore also have excessive joint laxity

Treatment = bisphosphonate therapy to increase bone mineral densisty (inhibit osteoclasts)

Question 10

OI type II

Answer 10

Most severe

Always lethal in utero or shortly after birth

AR

Blue to black sclera
Thin beaded ribs
Crumpled long bones
Limited cranial and/or facial bone ossification
Short curved limbs

Question 11

OI Type III

Answer 11

Severe but survive past perinatal period

Sustain fractures during birth —> progressive defomration —> wheel chair

IQ is normal

Potential child abuse cases..

Pale blue to normal sclera that normalizes over time

Wormian bones (extra pieces of bone within a suture in the skull)

Question 12

OI Type IV

Answer 12

Much more normal quality of life

Break a few bones a year

Normal sclera

Deformity of long bones and psine

Basilar impression of the skull resulting in brainstem compresion

Hearing loss (breaking of middle ear bones)

Abnormal teeth

Question 13

OI Type I

Answer 13

Least severe

Normal quality of collagen but just dont make enough of it

Slight spinal curve

Loose joints

Poor muscle tone

Blue-grey sclera

Hearling loss