CASE 74

By: Dr. Amna Kashgari MD,SSC-Rad

HISTORY: A 4-year-old boy with short stature, dysmorphic feature and waddling gait.

What are your findings?

What is your diagnosis?

What is the fatal complication of this entity?

FINDINGS:

Anteroposterior (AP)pelvic radiograph and lower limb (A) demonstrate progressive narrowing of the interpediculate distance, Squared iliac wings with narrow sacroiliac notches with champagne glass appearance of the pelvic inlet and horizontal acetabulum with reduced acetabular angle. The femuri are short (rhizomelia) with wide metaphysis. Relatively long fibula noted with bowing.

Right hand radiograph (B) shows short phalanges with fingers of equal length (trident hand).

DIAGNOSIS:

 Achondroplasia.

Complication:

Sudden death from narrowing of the foramen magnum and non-communicating hydrocephalus.

PEARLS AND DISCUSSION:

Achondroplasia is the most common skeletal dysplasia. Prevalence of 1 in 25,000-50,000 births. Males are affected more frequently than females.

Autosomal dominant or sporadic mutation disorder of abnormal enchondral bone ossification.

It results in Rhizomatic dwarfism: It means the proximal bones affected more than the distal bone. Therefore, the humerus and femur are more involved than the radius and tibia.

Radiology diagnosis depend on plain X-ray findings:

• Skull: Skull base hypoplasia with constriction of the foramen magnum which lead to:

  • Frontal bossing.

  • Enlarged caldarium and mandible.

  • Hypoplasia of the midface: flat nasal bridge.

• Hands and feet

  • Short phalanges.

  • Fingers of equal length (trident hand).

• Spine

  • Progressive narrowing of the interpediculate distance.

  • Thickening and shortening of the pedicles.

  • Decreased height of vertebral bodies with scalloped posterior margin.

  • Anterior wedging may produce a “bullet” shape.

  • Scoliosis.

• Pelvis

  • Squared iliac wings.

  • Narrow sacroiliac notches with Champagne glass appearance of the pelvic inlet.

  • Horizontal acetabulum with reduced acetabular angle.

• Long bones

  • Bones are short and wide with widen metaphysis “trumpet appearance”.

  • Ball in socket epiphysis: inverted V shaped distal femoral epiphysis.

  • Bowing.

  • Dis-proportionally long fibula.

  • Short Ulna.

Complications:

• Spinal stenosis.

• Non-communicating Hydrocephalus secondary to narrowing of the foramen magnum.

• Sudden death.

FURTHER READIING:

1. Lane F Donnelly. Fundamental of pediatric radiology. ISBN-13: 978-0721690612

2. Johan G Blickman, Bruce R Parker, Patrick D Barnes. Pediatric Radiology: The Requisites, 3e.ISBN-10: 0323031250