Bone
Developmental abnormalities
Dwarfism


Topic Completed: 1 June 2012

Minor changes: 16 June 2020

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PubMed Search: Dwarfism[title]

Dariusz Borys, M.D.
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Cite this page: Borys D Dwarfism. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/boneachondroplastic.html. Accessed July 4th, 2020.
Achondroplastic dwarfism
  • Major cause of dwarfism
  • Reduction in chondrocytes at growth plate is due to defect in fibroblastic growth factor receptor 3 gene (FGFR3)
  • FGFR3 inhibits cartilage proliferation, and is constitutively active in these patients
  • Autosomal dominant, but 80% of cases are new mutations
  • Clinical image
  • Clinical features:
    • Short proximal extremities, normal trunk, enlarged head (bulging forehead, depression of root of nose)
    • Normal intramembranous bone formation, so bone cortices seem thickened compared to short bone length
    • Normal life, IQ, reproductive status
  • Micro description: narrow / disorganized zones of proliferation and hypertrophy in growth plates; chondrocytes in clusters, not columns; base of growth plate has prematurely deposited struts of bone which seal the plate
Thanatophoric dwarfism
  • Also called thanatophoric dysplasia
  • “Thanato”: denoting death
  • Lethal form of dwarfism
  • Occurs in 1 per 20,000 live births
  • Case report: variant in 18 week male fetus (Arch Pathol Lab Med 1993;117:322)
  • Micro description: diminished proliferation of chondrocytes and poor columnization of zone of proliferation
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