Osteoma of the Paranasal Sinus

General Considerations

• Most common tumor of the paranasal sinuses
• Most frequently seen in the frontal and ethmoid sinuses
• Benign tumor of membranous bone consisting of dense, compact bone
• Majority of paranasal osteomas are discovered serendipitously
• In the skull, they usually arise from the outer table

Clinical Findings

• Most are asymptomatic
• Rarely, large osteoma in the frontal or ethmoid region may displace globe forward and cause proptosis
• Obstruction of a sinus ostium may lead to infection or formation of a mucocele
• Very rarely, an osteoma may erode through the dura leading to cerebrospinal fluid rhinorrhea or intracranial infection

Imaging Findings

• Well-circumscribed, sharply-marginated round and very dense lesions usually less than 2 cm in size
• Usually grow into the sinus
• Multiple paranasal osteomas are found in Gardner’s syndrome
• Multiple osteoma of the mandible and maxilla, along with the frontal, sphenoid and ethmoid sinuses, rarely the long bones or phalanges
• Cutaneous and soft tissue tumors
• Association between colonic polyps with a predilection to malignant degeneration
  

 
Osteoma of the Frontal Sinus. Two frontal views of the skull demonstrate an incidental rounded, sclerotic lesion growing into the right frontal sinus (white arrows).