Ossfying fibromas (OF) (also commonly referred to as osteofibrous dysplasia (OFD), especially when in the extremities) are benign bone lesions that should be differentiated from non ossifying fibromas 1 and fibrous dysplasia (osteoblastic rimming).
These lesions are most frequently encountered in young children (often under 10 years of age).
Histologically, they comprise haphazardly distributed lamelleated bony spicules on a background of fibrous stroma. Despite being benign they can be locally aggressive. Immunohistochemical staining of lesions show keratin positive cells in majority of the cases.
- lower extremity:
- tibia: commonest site 5 (90% of the time). There is a predilection for the anterior tibial cortex.
- femur: occurs in a diaphysial location
- mandible and maxilla: these are examples of cementum-poor cemento-ossifying fibromas 2 (see WHO classification scheme for odontogenic tumours)
- sinonasal: expansile lesions with peripheral ossification and central lucency (case 3)
Plain film and CT
- seen as a well-circumscribed lesion
- demonstrates evidence of intracortical osteolysis with characteristic sclerotic band (osteoblastic rimming)
- moderate cortical expansion
- homogenous lesion matrix
Reported signal characteristics include
- T1: low signal
- T2: iso-high signal
- T1 C+ (Gd): typically shows enhancement
- pathological fracture(s)
- limb bowing
Treatment and prognosis
Tends to regress over time. For locally aggressive lesions, surgical resection is often curative although recurrence has been reported.
Imaging differential considerations include
- fibrous dysplasia: has no osteoblastic rimming
- adamantinoma: may share a common origin with ossifying fibromas
- osteoid osteoma
The differential diagnosis for bone tumours is dependant on the age of the patient, with a very different set of differentials for the paediatric patient.
- bone-forming tumours
- enchondromatosis (Ollier disease)
- Maffucci syndrome
- chondromyxoid fibroma
- fibrous bone lesions
- bone marrow tumours
- other bone tumours or tumour-like lesions
- skeletal metastases
- 1. Chang HJ, Donahue JE, Sciandra KT et-al. Best cases from the AFIP: juvenile ossifying fibroma of the calvaria. Radiographics. 29 (4): 1195-9. doi:10.1148/rg.294085240 - Pubmed citation
- 2. Jung SL, Choi KH, Park YH et-al. Cemento-ossifying fibroma presenting as a mass of the parapharyngeal and masticator space. AJNR Am J Neuroradiol. 1999;20 (9): 1744-6. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 3. Kendi AT, Kara S, Altinok D et-al. Sinonasal ossifying fibroma with fluid-fluid levels on MR images. AJNR Am J Neuroradiol. 2003;24 (8): 1639-41. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 4. Kamineni S, Briggs TW, Saifuddin A et-al. Osteofibrous dysplasia of the ulna. J Bone Joint Surg Br. 2001;83 (8): 1178-80. doi:10.1302/0301-620X.83B8.12114 - Pubmed citation
- 5. Lee RS, Weitzel S, Eastwood DM et-al. Osteofibrous dysplasia of the tibia. Is there a need for a radical surgical approach? J Bone Joint Surg Br. 2006;88 (5): 658-64. doi:10.1302/0301-620X.88B5.17358 - Pubmed citation
- 6. Levine SM, Lambiase RE, Petchprapa CN. Cortical lesions of the tibia: characteristic appearances at conventional radiography. Radiographics. 23 (1): 157-77. doi:10.1148/rg.231015088 - Pubmed citation
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