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Classification and external resources
X-ray of the left femur of a 10 year old boy with an exostosis at the lateral side, just above the knee.
ICD-9 726.91
DiseasesDB 18621
MeSH D005096

An exostosis (plural: exostoses) is the formation of new bone on the surface of a bone.[1] Exostoses can cause chronic pain ranging from mild to debilitatingly severe, depending on the shape, size, and location of the lesion.

When used in the phrases "Cartilaginous exostosis" or "Osteocartilaginous exostosis", it is considered synonymous with Osteochondroma. Some sources consider the terms to mean the same thing even without qualifiers, but this interpretation is not universal.

Fossil record[edit]

Evidence for exostosis found in the fossil record is studied by paleopathologists, specialists in ancient disease and injury. Exostosis has been reported in dinosaur fossils from several species, including Acrocanthosaurus atokensis, Albertosaurus sarcophagus, Allosaurus fragilis, Gorgosaurus libratus, and Poekilopleuron bucklandii.[2]

Related conditions[edit]

See also[edit]


  1. ^ "exostosis" at Dorland's Medical Dictionary
  2. ^ Molnar, R. E., 2001, Theropod paleopathology: a literature survey: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, p. 337-363.

External links[edit]