Osteoma

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For more information about osteoid osteoma that is not associated with sino-orbital osteoma, see osteoid osteoma

Osteoma Microchapters
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Patient Information
Overview
Historical Perspective
Classification
Pathophysiology
Causes
Differentiating Osteoma from other Diseases
Epidemiology and Demographics
Risk Factors
Screening
Natural History, Complications and Prognosis
Diagnosis
Staging
History and Symptoms
Physical Examination
Laboratory Findings
X Ray
CT
MRI
Ultrasound
Other Imaging Findings
Other Diagnostic Studies
Treatment
Medical Therapy
Surgery
Primary Prevention
Secondary Prevention
Cost-Effectiveness of Therapy
Future or Investigational Therapies
Case Studies
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Rohan A. Bhimani, M.B.B.S., D.N.B., M.Ch.[2]

Synonyms and keywords: Osteoma; Osteomata; Osteoncus; Ivory osteoma; Mature osteoma; Mixed osteoma; Homoplastic osteoma; Heteroplastic osteoma; Osteomas; Ivory exostosis; Sino-orbital osteoma; Sino-nasal osteoma; Paranasal sinus osteoma; Skull vault osteoma; Mandibular osteoma

Overview

Osteoma (also known as Osteomata) is a slow growing benign tumor of bone, occurring most commonly in the craniofacial skeletal structures, primarily in the nasal and paranasal (75-90%) sinuses. Osteoma arises from bone overgrowth, which is normally composed of connective tissue. Osteomas are slow growing tumors composed of compact or mature trabecular bone limited to craniofacial bones. Osteoma may be incidentally identified as a mass in the skull, mandible, or as the underlying cause of sinusitis or mucocele formation within the paranasal sinuses. When they are multiple, Gardner syndrome should be considered. Osteoma represents the most common benign neoplasm of the nose and paranasal sinuses. The causes remain uncertain, but commonly accepted theories propose embryologic, traumatic, or infectious causes. Osteomas are usually asymptomatic. Excision may be performed if osteoma is responsible for symptoms.

Historical Perspective

• In 1898, the description of craniofacial osteoma was first reported by Paul Schulze.
• In 1951, Eldon J. Gardner (1909–1989) a geneticist first described the occurrence of multiple osteomas in hereditary familial adenomatous polyposis (FAP).
• In 2014, The Lancet published an article named "Did René Descartes have a giant ethmoidal sinus osteoma?" the authenticity has been confirmed by anthropological and historical investigations to be true.

Classification

Osteoma can be classified based on imaging findings.

Enneking (MSTS) Staging System

• The Enneking surgical staging system (also known as the MSTS system) for benign musculoskeletal tumors based on radiographic characteristics of the tumor host margin.
• It is widely accepted and routinely used classification.

Stages	Description
1	Latent: Well demarcated borders
2	Active: Indistinct borders
3	Aggressive: Indistinct borders

Pathophysiology

• The exact etiology of osteoma is unknown.
• The possibility of a reactive mechanism, triggered by trauma or infection, has been suggested.
• Osteoma arises from bone overgrowth, which is normally composed of connective tissue.
• Osteomas are slow growing tumors composed of compact or mature trabecular bone limited to craniofacial bones.
• Very rarely osteomas of the facial bones may be associated with Gardner's syndrome.
• Osteomas have a particular frequency distribution within the paranasal sinuses: frontal sinuses 80%, ethmoid air cells 15%, maxillary sinuses 5% and sphenoid sinus rare.

Genetics

• The hallmark of multiple osteomas is a mutation in the APC gene, that results in the Gardner syndrome.

Causes

• The cause of osteoma has not been identified.

Differentiating ((Page name)) from Other Diseases

Osteoma must be differentiated from other diseases that cause sinus or facial pain, headache, and changes to or loss of sense of smell, such as other osteogenic tumors, fibrous dysplasia, and chronic sinusitis.

Differential Diagnosis	Similar Features	Differentiating Features
Fibrous dysplasia	Benign, often an incidental finding, affects the same group of patients, and symptoms include facial pain and headache	In fibrous dysplasia, differentiating features include: More common presentation is on ribs: 28%, no gender predilection, and complete resection is usually not possible
Osteoblastoma	Benign, incidental, and male predilection	In osteoblastoma, differentiating features include: normally affect the axial skeleton, lesions are typically larger than 2 cm, and surgical excision is often the treatment of choice
Adamantinomas	Benign, slow growing, and similar clinical onset	In adamantinomas, differentiating features include: locally aggressive tumor, common in the 3rd to 5th decades of life, and location is usually confined to the jaw
Chronic sinusitis	Affects same group of population (young to middle aged adults) and the clinical presentation is similar	In chronic sinusitis, differentiating features include: fever, previous history of acute sinusitis, lack of facial deformation or imaging findings compatible with osteoma

Epidemiology and Demographics

• The prevalence of osteoma is approximately 3000 per 100,000 individuals worldwide.
• The incidence of osteoma remains unknown.
• Patients of all age groups may develop osteoma.
• The average patient age varies from 25 to 35 years.
• The mean age of the patients with osteoma is is 37 years.
• Men are more commonly affected than women, with a 3:1 ratio.
• There is no racial predilection to osteoma.

Risk Factors

There are no established risk factors for osteoma.

Screening

Screening for multiple osteomas is recommended among patients with family history or/and a confirmed diagnosis of Gardner syndrome. Thyroid exam and annual ultrasound, should be performed starting at age 10 to 12 years.

Natural History, Complications, and Prognosis

• If left untreated, osteoma progression occurs slowly and is then followed by facial distortion.
• Common complications of osteoma include:
  • Proptosis
  • Facial deformity
  • Airway obstruction
  • Sensory loss
  • Anosmia
  • Visual loss
• Prognosis is generally excellent,the lesion does not recur after surgical excision and it is not associated with malignant change.

Diagnosis

Diagnostic Study of Choice

Biopsy is the diagnostic study of choice for the diagnosis of osteoma.

• Gross appearance of osteoma include:
  • Osteomas have a spongy to densely appearance, conformed of in a polypoid and lobullated shape.[1]
  • The median size tumor size is 3.0 cm (range 0.5-8 cm).
  • Osteomas have a smooth surface and composed of dense compact bone (ivory osteoma), trabecular bone (mature osteoma, or both patterns).

Histology of osteoma.Source: Case courtesy of Nephron [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0) or GFDL (http://www.gnu.org/copyleft/fdl.html), from Wikimedia Commons]

• Histological appearance includes:
  • Presence of dense compact mature bone in paucicellular fibrous stroma.
  • Large trabeculae of mature lamellar bone can be also be seen.

History and Symptoms

• Small osteomas are asymptomatic and usually incidental findings.
• Common symotoms of osteoma include:
  • Headache
  • Nasal congestion
  • Facial pain
  • Facial tenderness
  • Loss of the sense of smell

Physical Examination

X-ray showing osteoma of the frontal sinus.Source: Case courtesy of Dr Ahmed Abdrabou, Radiopaedia.org, rID: 42250

• Patients with osteoid osteoma usually appears well.
• Common physical examination findings of osteoid osteoma include:
  • Facial tenderness
  • Nasal obstruction and discharge
  • Tapping over a sinus area produces dull sound
  • Physical deformity over mastoid or facial area

Laboratory Findings

There are no diagnostic laboratory findings associated with osteoma.

Electrocardiogram

There are no ECG findings associated with osteoma.

X-ray

• Three views of affected bone or joint are recommended.
• Radiological findings for osteoma include:
  • Well circumscribed mass
  • Varying amounts of central lucency
  • Lobulated mass occupying frontal or maxillary sinus

Echocardiography or Ultrasound

CT showing osteoma of the mandible.Source: Case courtesy of Dr Ahmed Abdrabou, Radiopaedia.org, rID: 42250

There are no echocardiography/ultrasound findings associated with osteoma.

CT scan

• CT findings of osteoma include:
  • Well-circumscribed mass of variable density
  • Ground-glass appearance
  • Exophytical mass growing out of a sinus

MRI

• MRI findings of osteoma include:
  • Low signal on all sequences.
  • Mature osteomas may demonstrate some marrow signal, but are also predominantly low on all sequences

Other Imaging Findings

There are no other imaging findings associated with osteoma.

Nasal Endoscopy

Nasal endoscopy findings include:

• Direct visualization of the nasal passages structures, and sinuses.
• Tumor location, size, and adjacent structure evaluation.

Treatment

Medical Therapy

There is no medical treatment for osteoma; the mainstay of therapy is surgery.

Surgery

Surgery is the mainstay of treatment for osteoma.

Indication

• For symptomatic lesions, local excision is performed.

Types of Surgery

• Medial maxillectomy with a lateral rhinotomy
• Craniofacial resection
• Endoscopic resection

Recurrence Rare recurrence may occur after several years.

Primary Prevention

There are no established measures for the primary prevention of osteoma.

Secondary Prevention

There are no established measures for the secondary prevention of osteoma.

References

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