Other tumors of bone
Subungual exostosis

Author: Nat Pernick, M.D. (see Authors page)

Revised: 20 July 2018, last major update June 2005

Copyright: (c) 2003-2018,, Inc.

PubMed search: Subungual [title] exostosis

Cite this page: Pernick, N. Subungual exostosis. website. Accessed December 11th, 2018.
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

Images hosted on PathOut server:

Distal phalanx of great toe

  • 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

Images hosted on PathOut server:

Moderately cellular cartilage

Reactive bone

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