Osteoma

Definition

 

Benign, hamartomatous bone-forming lesion arising from the surface of the affected bone

 

Aetiology

 

Excrescence of dense bone which arises from the surface of bones formed by intra-membranous ossification

 

Epidemiology

 

Age 25-50

 

M=F

 

Site

 

Skull or mandible

- classically

 

Shafts of long bones

- often see posterior femur

- similar location to parosteal OS

 

"flat bones and tibial diaphysis"

 

Pathology

 

Gross

- dome-like outcropping

- dense bone

- covered by a capsule confluent with the periosteum

 

Histology

- heavy trabecular bone

- matures into dense cortical bone 

- over-maturation 

- many small haversian canals

- some canals are obliterated 

 

DDx

 

Parosteal osteosarcoma

Exostosis

 

Prognosis

 

Active stage 2 lesion 

- never goes to 3 or 1

 

Association

 

Gardner's Syndrome

 

Management

 

Intracapsular or marginal excision 

- removing the lesion from the surface of the bone

- negligible risk of recurrence

- wide en bloc excision not necessary