Ossifying fibroma

Last revised by Joshua Yap on 15 Oct 2022

Ossifying fibromas are benign bone lesions that should be differentiated from non-ossifying fibromas and fibrous dysplasiaOsteofibrous dysplasia is considered as a separate pathological entity in view of its different presentation and treatment, although histopathologically similar to ossifying fibroma. 

These lesions are most frequently encountered in young children (often <10 years).

  • lower extremity

    • tibia: most frequent 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 tumors)

  • sinonasal: expansile lesions with peripheral ossification and central lucency

They comprise haphazardly distributed lamellated bony spicules on a background of fibrous stroma. Despite being benign, they can be locally aggressive.

Immunohistochemical staining of lesions shows positive keratin cells in the majority of the cases.

  • well-circumscribed lesion

  • evidence of intracortical osteolysis with a characteristic sclerotic band (osteoblastic rimming)

  • moderate cortical expansion

  • homogeneous lesion matrix

Reported signal characteristics include:

  • T1: low signal

  • T2: iso-high signal; fluid-fluid levels may be present 8

  • T1 C+ (Gd): typically shows enhancement

Ossifying fibromas tend to regress over time. For locally aggressive lesions, surgical resection is often curative although recurrence has been reported.

Imaging differential considerations include:

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