Subungual Exostosis OR Osteochondroma

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Eenie Meenie Miney Mo: a truly amazing democratic way of selecting something, although Im not sure it is ever a good idea to catch a tiger by his toe or tail. This phrase has typically been applied when a child cannot decide between the Hershey bar OR the Snickers, knowing both cannot be had. I dont think this fun childrens quote will help, or matter to be honest, when it comes to choosing between a Subungual Exostosis OR Subungual Osteochondroma. The reason being that both are very similar and are difficult to differentiate.

Subungual Exostosis

  • Has an unclear etiology, although trauma is highly suspected in some instances.
  • More common in the 20-40 year old age range
  • It is a benign tumor that is common at the distal phalanx of the fingers or toes
  • They are relatively slow growing and only cause discomfort or pain as they become larger and push up on the overlying nail causing rubbing and irritation from an adjacent toe or shoe.
  • Radiographically
  • Shows cancellous (thinner) bone growing from the base off the distal phalanx
  • Its base may be broad or narrow
  • No destructive changes to the underlying bone
  • Histologically
  • Its cartilage cap is made from fibrocartilage that will varying in thickness as the lesion grows.

Subungual Osteochondroma

  • Thought be caused by a disturbance in development of the boney cortex
  • Typically occurs in the adolescent age group
  • It is a benign tumor that can occur anywhere
  • Relatively slow growing until puberty, but then can grow rapidly until through adolescence
  • Causes pain very similar to that of a subungual Exostosis.
  • Radiographically
  • The cortex (outer portion) of this bone tumor is confluent with that of the underlying bone
  • May have a broad or narrow base
  • Histologically
  • Its cartilage cap is made up of Hyaline cartilage NOT fibrocartilage.
  • The cartilage cap can become much larger than that seen in an Exostosis

NOTE: the major differences are seen radiographically AND histologically

Treatment is similar: surgical excision.

If you or someone you know is experiencing similar problems OR has any other related foot/ankle complaint, please contact Dr. Bowman at 713-467-8886 or visit

Category: Bone Problems

Tags: Bone Problems, Bone Spurs, Bump on Foot, Osteochondroma, Subungual Exostosis