Bone forming tumors (not osteosarcoma)

Author: David R. Lucas, M.D.

Topic Completed: 1 August 2013

Revised: 28 December 2018

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

PubMed Search: Osteoma[title]

Page views in 2018: 11,408
Page views in 2019 to date: 7,565
Cite this page: Lucas DR Osteoma. website. Accessed June 24th, 2019.
Definition / general
  • Benign bone-forming tumor composed of compact or mature trabecular bone limited almost exclusively to craniofacial bones, especially paranasal sinuses (Arch Pathol Lab Med 2009;133:1587)
  • Ivory exostosis, sino orbital osteoma, sino nasal osteoma
  • Adults and children, mean age 37 years
  • Men outnumber women, 3:2
  • Paranasal sinuses (frontal sinus most common), orbit, nasal cavity, jaw bones, cranial vault
  • Unknown
Clinical features
  • Paranasal sinus tumors associated with pain, headache, facial distortion, proptosis, visual changes, mucocele, sinusitis, CSF leakage, pneumatocele, meningitis, and cerebral abscess
  • Associated with Gardner syndrome
  • Radiographic findings often helpful
Radiology description
  • Well demarcated tumors
  • Dense compact bone with varying amounts of central lucency
Radiology images

Dense lobular mass in frontal sinus

Images hosted on other servers:
Missing Image

Various images

Prognostic factors
  • Prognosis related to proximity to essential anatomic structures and completeness of resection
  • ~20% have symptomatic recurrences
Case reports
  • Surgical excision for symptomatic tumors
Clinical images

Images hosted on other servers:

Large osteoma of maxillary sinus

Exophytic osteoma ("ivory exostosis")

Multiple bony hard swellings on forehead

Gross description
  • Sessile, polypoid shape
  • Median size 3.0 cm (range 0.5 - 8 cm)
  • Smooth, bosselated surface
  • Cut surface with dense compact bone (ivory osteoma), trabecular bone (mature osteoma, or both patterns)
Gross images
Contributed by Dr. David R. Lucas

Osteoblastoma-like osteoma with polypoid shape and bosselated surface (left) and zones of dense, compact and trabecular bone on cut section

Contributed by Dr. Mark R. Wick


Images hosted on other servers:

Osteoma with smooth bosselated surface

Microscopic (histologic) description
  • Composed primarily of dense, compact bone and broad trabeculae of mature bone within paucicellular fibrous stroma
  • Outer surface is sharply demarcated and lined by respiratory epithelium in sinus tumors
  • Areas resembling osteoblastoma (narrow, anastomosing trabeculae of woven bone with osteoblastic rimming within a fibrovascular stroma) are common (38%)
  • Pagetoid bone common
Microscopic (histologic) images

Thick trabeculae of bone

Contributed by Dr. David R. Lucas

Dense, compact bone and Haversian canals

Broad trabeculae of lamellar bone

Areas indistinguishable from osteoblastoma

Pagetoid bone with basophilic reversal lines

Contributed by Dr. Mark R. Wick


Images hosted on other servers:

Various images

Differential diagnosis
  • Ossifying fibroma: more cellular fibrous stroma, small ossicles and irregular bony trabeculae, much less mature bone
  • Osteoblastoma: rarely found in paranasal sinuses, expansile intraosseous or periosteal tumor, much less mature bone
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