Bone
Bone forming tumors (not osteosarcoma)
Osteoma

Author: David Lucas, M.D. (see Authors page)

Revised: 26 October 2016, last major update August 2013

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed Search: Osteoma[title]
Cite this page: Osteoma. PathologyOutlines.com website. http://pathologyoutlines.com/topic/boneosteoma.html. Accessed December 8th, 2016.
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)
Terminology
  • Ivory exostosis, sino orbital osteoma, sino nasal osteoma
Epidemiology
  • Adults and children, mean age 37 years
  • Men outnumber women, 3:2
Sites
  • Paranasal sinuses (frontal sinus most common), orbit, nasal cavity, jaw bones, cranial vault
Etiology
  • 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
Diagnosis
  • Radiographic findings often helpful
Radiology Description
  • Well demarcated tumors
  • Dense compact bone with varying amounts of central lucency
Radiology Images

Images hosted on Pathout server:

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
Treatment
  • Surgical excision for symptomatic tumors
Clinical Images

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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

Images hosted on Pathout server:

Skull - contributed by Dr. Mark R. Wick



Images hosted on Flickr:

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



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Osteoma with smooth bosselated surface

Micro 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
Micro Images

Images hosted on Pathout server:

Skull - contributed by Dr. Mark R. Wick

Thick trabeculae of bone



Images hosted on Flickr:

Dense, compact bone and Haversian canals

Broad trabeculae of lamellar bone

Areas indistinguishable from osteoblastoma

Pagetoid bone with basophilic reversal lines



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