Osteoma overview

# 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%) cavities. 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, Paul Schulze, was the first to describe a craniofacial skeletal osteoma.

# Classification
Osteoma may be classified into either sporadic or multiple forms. The different subtypes of osteoma include: ivory osteoma, mature osteoma, and mixed osteoma.

# Pathophysiology
Osteoma is a  slow growing benign tumor of bone, occurring most commonly in the craniofacial skeletal structures, primarily in the nasal and paranasal (75-90%) cavities. 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. The most common gene affected in multiple osteoma is the APC gene.

# Causes
The cause of an osteoma has not been identified, but commonly accepted theories propose embryological, traumatic, or infective causes.

# Differentiating Osteoma 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 tumours, fibrous displasia, and chronic sinusitis.

# Epidemiology and Demographics
Osteoma is the most common benign neoplasm of the nose and paranasal sinuses. The prevalence of osteoma is 3% in general population. It mainly affects adults and children. The mean age at diagnosis is 37 years. Men are more commonly affected than women, with a 3:2 ratio.

# Risk Factors
The risk factors of osteoma remain unknown.

# 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 sites of location include paranasal sinuses. Complications of osteoma are usually related to tumor size. The prognosis is regarded as excellent after surgical excision. Features associated with worse prognosis after surgery are tumor location, depth, and size.

# Diagnosis

## Staging
There is no established system for the staging of osteoma.

## History and Symptoms
The hallmark of osteoma is facial pain and headache. A positive history of Gardner syndrome is suggestive of multiple osteomas. Symptoms related with osteoma will vary depending on the size and location of the tumor. Small osteomas are asymptomatic and usually incidental findings. Conversely, common symptoms of large paranasal sinus osteomas may be headache, nasal congestion, and anosmia.

## Physical Examination
Common physical examination findings of osteoma include the nasal discharge, facial tenderness, and facial deformity.

## Laboratory Findings
There are no diagnostic laboratory findings associated with osteoma.

## X Ray
On x-ray, osteoma demonstrates a dense well circumscribed mass with varying amounts of central lucency. Caldwell and Waters view are the radiographic positions of choice for the evaluation of osteomas.

## CT
On CT scan, osteomas demonstrate a well circumscribed mass of variable density, varying from very dense (similar in density to normal cortical bone) to less dense with a ground-glass appearance.

## MRI
On MRI, ivory osteomas are low on all sequences. Mature osteomas may demonstrate some marrow signal, but are also predominantly low on all sequences.

## Ultrasound
There are no ultrasound findings associated with osteoma.

## Other Imaging Findings
There are no other imaging findings associated with osteoma.

## Other Diagnostic Studies
Other diagnostic study for osteoma is nasal endoscopy. Biopsy may be obtained with nasal endoscopy, depending on the location of the tumor.

# Treatment

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

## Surgery
Surgery is the mainstay of therapy. Surgical intervention is only recommended for the management of symptomatic osteoma.

# Primary Prevention
There is no primary prevention for osteoma.

# Secondary Prevention
Secondary prevention for osteoma includes screening for multiple osteomas 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.