Imaging description

Osteofibrous dysplasia (OFD) almost exclusively occurs in the diaphysis of the tibia. Multiple cystic lesions are seen in the anterior cortex of the middle to proximal diaphysis of the tibia (Figure 58.1). There may be mild expansion with increased sclerosis in the surrounding cortex. Ipsilateral fibula may be involved. Similarly, adamantinoma most often occurs in the tibia, and typically involves the middle diaphysis. Adamantinoma is often purely lytic, eccentric, and expansile involving the anterior cortex (Figure 58.2). Ipsilateral fibula is occasionally involved.

Importance

Osteofibrous dysplasia is a benign fibroosseous lesion, named by Campanacci in 1976 in reference to histologic resemblance to fibrous dysplasia. Osteofibrous dysplasia most frequently occurs in the first two decades of life. Adamantinoma is a low-grade malignant bone tumor that typically affects patients older than 20 years. There is an intermediate entity called OFD-like adamantinoma or differentiated adamantinoma supporting the concept that these lesions are related. Immunohistochemical staining for cytokeratin confirms the epithelial nature of these lesions. There are well-documented cases, in which patients initially diagnosed as OFD or OFD-like adamantinoma have developed classic adamantinoma. Whether one lesion can progress or regress to another remains controversial. Surgical management is necessary for adamantinoma. The treatment of OFD-like adamantinoma is not well established. Because of the benign nature of OFD the treatment is based on the symptoms. Some recommend observation without surgical intervention for OFD as it ceases to progress towards skeletal maturity.