Bone & joints
Other chondrogenic tumors
Subungual exostosis


Topic Completed: 1 June 2005

Minor changes: 29 October 2019

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PubMed search: Subungual [title] exostosis


Nat Pernick, M.D.
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Cite this page: Pernick N Subungual exostosis. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/bonesubungualexostosis.html. Accessed August 6th, 2020.
Definition / general
  • Also called Dupuytren exostosis
  • Rare, osteochondroma-like lesion under nail bed, usually of great toe
  • A type of myositis ossificans
  • Appears to be neoplastic based on t(X;6) present
  • Usually male teenagers / young adults
  • Painful, slow growing, may produce ulceration of nail
  • May be associated with local trauma, infection or chronic irritation
Radiology description
  • Calcifying lesion projecting from distal phalanx
Radiology images

Distal phalanx of great toe

Treatment
  • Simple excision, may recur, particularly with incomplete excision
  • Does not transform
Microscopic (histologic) description
  • Spindle cell proliferation on surface of cartilage, resembling a cap, with underlying trabecular bone formation
  • May be hypercellular and mitotically active
Microscopic (histologic) images

Moderately cellular cartilage

Reactive bone

Molecular / cytogenetics description
Differential diagnosis
  • Osteochondroma: different location, no spindle cell proliferation
  • Sarcoma: marked atypia
Additional references
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