dr james c wittig, orthopedic oncologist, new york, new jersey
About Dr. Wittig
Osteoma

GENERAL INFORMATION

Osteoma is a rare benign bone tumor, composed of mature osseous tissue.  It presents as a protruding mass of dense periosteal intramembranous bone, usually on surface of host bone. It is abnormally dense but is normal bone formed in the periosteum. In the extremities they are often an incidental finding. 

CLINICAL DATA

 A benign periosteal tumor
 Rare condition (confused with reactive bone, postraumatic or postinfection, etc)
 Almost exclusively affect:
• Skull
• Parasal sinus
• Facial bones
 Multiple osteomas/osteomas involving a long bone, rule out Gardner syndrome (osteomas, colon polyps and desmoid tumors) 

Differential diagnosis
 Ossified fibrous dysplasia
 Solid odontomas
 Osteochondromas (in long bones)
 Parosteal osteosarcoma

CLINICAL PRESENTATION

Signs/Symptoms
 Intracraneal osteomas
• Sinus osteomas show signs of nasal and paranasal sinus obstruction
• Extracraneal osteomas
• May cause symptomatic nerve compression


Prevalence
• Sinus osteomas show a male predominance (2:1)
• Maxilla and mandible show female preference (3:1)


Age
• Patients ages range from 10 to 79 years, but most common  in the 4th an 5th decades of life

Sites
• Cranium, sinuses and mandible most common
• Long bones-rare

RADIOGRAPHIC PRESENTATION

Plain x-ray
 Sharply defined, radiopaque smooth, homogeneous bone protruding from the surface of a bone
• Almost appears as a localized thickening of the bone



Fig. 1. AP xray of forearm show a superficial bone lesion in the shaft of the ulna consistent with an osteoma.


Fig. 2. AP xray of hand show a well circunscribed bone lesion on the 3rd index consistent with a small osteoma.

PATHOLOGY

Gross
 Most lesions are compact and resemble dense cortical bone

Microscopic
 Nodules of dense, mature, lamellar bone with orderly arrangement and haversian systems (cortical)
• The bone is very orderly and mature, and organized into lamellae
• The cells are uniform and have small nuclei
• No nuclear pleomorphism and no mitosis


Fig. 3. Low power magnification of lesion, shows a dense thickened lamellar bone with haversian systems. 

PROGNOSIS

Biological Behavior
 Sinus lesions may lead to sinusitis or grow into cranial vault
• Recurrence rarely develops

TREATMENT

• Excision vs Observation depending on location and symptoms
• Colonoscopy if Gardner syndrome is suspected
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