Summary
  • Smooth well-defined margins / well-corticated.
  • Homogenous radiopaque if cortical type, trabecular bone if cancellous bone.
  • Radiopaque projection on a broad base.
  • More common in the mandible than in the maxilla / Frontal sinus, ethmoidal sinuses, posterior mandible/ less common in maxillary sinuses.
  • If large, it can displace soft tissues.
  • Over 40 years old / Female predilection 3:1
  • Asymptomatic unless it interferes with normal function.


DDX
    (If osteoma is located in posterior mandible)

  • Osteochondroma
  • Osteophytes
  • Condylar hyperplasia

Osteoma


Definition

Osteoma is a benign tumor of bone which occurs most commonly on the skull and jaw bones. It can be subdivided into cancellous, compact, and both. It is characterized by bony protuberance of mature lamellar or woven bone that usually arises in membranous bones. They may occur either externally or within the paranasal sinuses. Osteoma is more common in the frontal and ethmoid sinuses than in the maxillary sinuses. It is not fully clear yet whether osteoma is a neoplasm or hamartomas. Osteoma may be solitary or multiple occurring on a single bone or numerous bones.


Clinical Features

Osteoma is usually found in patients over 40 years old. There is a female predilection of 3:1. Cancellous osteoma has high incidence rate in females while cortical osteoma is more common in males. The lesion is slowly enlarging and painless until its size or position interferes with function. Osteoma is discovered incidentally during radiographic examination. Osteoma can grow large enough to cause asymmetry in jaws. Multiple osteomas of the jaws as well as of long bones and skull are a characteristic manifestation of Gardner’s syndrome and familial adenomatous polyposis (FAP).


Radiographic Features

Osteoma is commonly found on mandible more than the maxilla. The most common locations are: posterior aspect of the mandible on the lateral aspect of ramus, below the molars inferior to the mandibular canal, coronoid process or mandibular condyle. Osteoma is usually round or oval appears as a homogenous radiopaque projection on a broad base, but rarely it will be pedunculated. The margins are smooth, well-defined, and well-corticated. The cancellous type has a normal trabecular bone pattern. Large osteomas can displace soft tissues such as muscles and can cause dysfunction.


Differential Diagnosis

The appearance is usually characteristic. Osteomas affecting the condylar head can be difficult to differentiate from osteochondroma, osteophytes, and condylar hyperplasia. Osteoma can look similar to a torus or an exostosis.


Treatment

No treatment is necessary unless osteoma interferes with normal function or cause cosmetic problem. Observing the lesion in this case is recommended. Surgical resection can be difficult in case of cortical osteoma.


Case Reports


CASE 1»

Cone Beam CT ReportHISTORY: A 33 years old male was referred for tomographic evaluation.


FINDINGS: This is an incidental finding of a well-defined radiopaque mass in the left anterior part of the ethmoidal sinus. The mass is homogenous and has smooth boundaries. There is no evidence of displacement or expansion. There is also thickening of the floor of the left maxillar sinus pointed by the arrow. This could indicate sinusitis.


IMPRESSION: The radiographic findings are suggestive of a benign lesion and it is consistent with osteoma.










Odontoma
Inflammatory Lesions of the Teeth and Jaws
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