= ELLIS-VAN CREVELD SYNDROME = MESODERMAL DYSPLASIA

= autosomal recessive acromesomelic dwarfism

Prevalence: 120 cases; in inbred Amish communities

Associated with: congenital heart disease in 50% (single atrium, ASD, VSD)

• ectodermal dysplasia:
  • scant / fine hair
  • absent / hypoplastic brittle spoon-shaped nails
  • irregular + pointed dysplastic teeth, partial anodontia, teeth may be present at birth
  • congenital heart disease
• obliteration of maxillary mucobuccal space (thick frenula between alveolar mucosa + upper lip); strabismus
• genital malformations: epispadia, hypospadia, hypoplastic external genitalia, undescended testicles

• hepatosplenomegaly
• accelerated skeletal maturation
• normal spine
• Skull
  • wormian bones
  • cleft lip
• Chest
  • elongated narrow thorax in AP + transverse dimensions exaggerating cardiac size
  • cardiomegaly ← frequently ASD / single atrium
  • short horizontal ribs + anterior osseous expansion → barrel-shaped chest
  • elevated clavicles
• Pelvis
  • small flattened ilium
  • trident morphology of acetabular roof = indentation in roof + bony spur (almost PATHOGNOMONIC)
  • acetabular + tibial exostoses
• Extremities
  • variety of micromelia (= thickening + mild shortening of all long bones):
    • acromelia = hypoplasia / absence of terminal phalanges
    • mesomelia = shortening of forearms + lower legs (radius + tibia >humerus + femur)
  • cone-shaped epiphyses
  • premature ossification of proximal humeral + femoral epiphyses
• Upper extremity
  • “drumstick” forearm = swelling of proximal end of ulna + distal end of radius
  • anterior dislocation of radial head ← shortening of ulna
  • carpal / tarsal fusion = frequent fusion of two / more carpal (hamate + capitate) + tarsal bones (after complete ossification)
  • supernumerary carpal bones
  • postaxial polydactyly common (usually finger, rarely toe) ± syndactyly of hands + feet
• Lower extremity
  • genu valgum:
    • slanting of proximal tibial metaphysis (← delayed development of tibial plateau)
    • excessive shortening of fibula
  • widening of proximal tibial shaft
  • medial tibial diaphyseal exostosis

OB-US:

• proportional shortening of long bones
• small thorax with decreased circumference
• increased cardiothoracic ratio
• ASD
• polydactyly

Prognosis: death within first month of life in 33–50% ← respiratory / cardiac complications

DDx: asphyxiating thoracic dysplasia (difficult distinction); rhizomelic achondroplasia