An exostosis (plural: exostoses) is the formation of new bone on the surface of a bone. Exostosis can cause chronic pain ranging from mild to debilitatingly severe, depending on where they are located and what shape they are.

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.)

• Hereditary multiple exostoses (HME)
• Subungal exostosis
• Buccal exostosis
• Surfer’s Ear (Exostosis of the ear canal)

• Osteoma
• Bone spur

• Marquette
• Template:GPnotebook (equates “Exostosis” with “osteochondroma”)]

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