Adamantinoma of the tibia masked by fibrous dysplasia. Report of three cases.

Three cases of adamantinoma of the tibia associated with and mimicking fibrous dysplasia or osteofibrous dysplasia are reported in children aged three, nine, and 16 years. The roentgenographic features were typical of intracortical fibrous dysplasia (osteofibrous dysplasia). These entities are not two distinct diseases, but rather are different histologic expressions of essentially the same process, which varies depending on location (predominantly intracortical or medullary) and age. Adamantinoma in children under ten years of age is not as rare as reported in the literature and was found in two of 14 cases in our files (14.3%). In some cases the fibrous dysplasialike component predominates over the scarce epithelioid islands of tumor cells and consequently is not recognized as adamantinoma. That may explain the frequent recurrences after incomplete excisions of supposed intracortical fibrous dysplasia lesions in young children. An extensive histopathologic study of the biopsy and/or surgical specimen by a specialized pathologist is therefore advisable.