Definition
Benign, hamartomatous bone-forming lesion arising from the surface of the affected bone
Etiology
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
Shafts of long bones
- often see posterior femur
- similar location to parosteal OS
Pathology
Gross
- dome-like outcropping of 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
Differential diagnosis
Parosteal osteosarcoma
Exostosis
Association
Gardner's Syndrome
Management
Intracapsular or marginal excision
Remove the lesion from the surface of the bone
- negligible risk of recurrence
- wide en bloc excision not necessary