Osteofibrous Dysplasia–like Adamantinoma of the Tibia in a 15-Year-Old Girl
Osteofibrous dysplasia and adamantinoma are rare lesions of primary benign and malignant bone tumors with an incidence of less than 1%. These lesions arise primarily in long bones with a predilection for the tibia and fibula. Osteofibrous dysplasia is a benign fibro-osseous lesion typically found in children younger than 10 years. Adamantinomas, however, are highly malignant and invasive tumors found predominantly in adult men, with an average age of diagnosis between 20 and 50 years.
Debate continues on whether osteofibrous dysplasia and adamantinoma occupy the same disease spectrum. Within the spectrum of pathology lies a rare benign lesion known as osteofibrous dysplasia–like adamantinoma. This intermediate form has the potential to spontaneously regress or transform into a malignant adamantinoma.
We report a rare case of an osteofibrous dysplasia–like adamantinoma of the tibia in a 15-year-old girl. The patient was followed with regular 3- to 6-month follow-ups. The lesion remained stable and showed no progression over 2 years. Given the benign nature of osteofibrous dysplasia and osteofibrous dysplasia–like adamantinoma and the malignant nature of adamantinoma, correctly diagnosing the lesion has significant treatment implications.
This case report highlights the rarity of this intermediate form and its potential to remain stable. Such lesions can be observed with frequent follow-ups without the need for surgical intervention.
Histologically, both osteofibrous dysplasia and osteofibrous dysplasia–like adamantinoma do not stain for cytokeratin on H&E stain. However, they can be differentiated based on immunohistochemical staining for cytokeratin. Osteofibrous dysplasia lesions exhibit diffuse staining whereas osteofibrous dysplasia–like adamantinoma lesions show focal staining of small nests of epithelial cells. Adamantinoma, in comparison, exhibits a biphasic pattern on H&E stain, representing areas of epithelial and osteofibrous cells. Immunohistochemical staining for cytokeratin of an adamantinoma reveals large nests of epithelial cells.
The association between osteofibrous dysplasia, osteofibrous dysplasia–like adamantinoma, and adamantinoma is not clearly established. However, it is widely believed that these 3 lesions represent a spectrum of the same disease and are linearly related in disease progression, with osteofibrous dysplasia at the benign end of the spectrum, osteofibrous dysplasia–like adamantinoma the intermediate form, and adamantinoma at the malignant end of the spectrum.11
Hazelbag and colleagues6 and Springfield and colleagues10 point out that osteofibrous dysplasia and osteofibrous dysplasia–like adamantinoma could be precursor lesions of adamantinoma. We found several studies in the literature that support and document progression from osteofibrous dysplasia and osteofibrous dysplasia–like adamantinoma to an adamantinoma.4,6,10,12 Other studies, however, showed no progression from either a benign osteofibrous dysplasia or an osteofibrous dysplasia–like adamantinoma lesion to a malignant adamantinoma. Park and colleagues13 described 41 cases of osteofibrous dysplasia that did not progress to adamantinoma. Kuruvilla and Steiner8 described 5 cases of osteofibrous dysplasia–like adamantinoma that showed no progression to adamantinoma. Additionally, our case has not progressed and has remained radiographically stable over a 2-year follow-up. Czerniak and colleagues7 and Ueda and colleagues14 postulated, based on histologic and immunohistochemical studies, that osteofibrous dysplasia–like adamantinoma might be a regressing form of an adamantinoma that is undergoing reparative processes that could result in complete elimination of all tumor cells.
In general, any lesion with absent to low malignant potential could be managed nonoperatively with periodic observation and without the need for surgical intervention. Thus, identification of a stable or nonprogressing osteofibrous dysplasia–like adamantinoma lesion has significant treatment implications. Campanacci and Laus15 at the Rizzoli Institute in Milan, through long term follow-up of their patients with osteofibrous dysplasia, found that most lesions had a tendency to regress spontaneously by puberty. They recommended that nonextensive osteofibrous dysplasia lesions should be observed, and surgery should be delayed until puberty. Gleason and colleagues16 also recommended nonoperative management of osteofibrous dysplasia lesions, with surgery used only for large, deforming, and highly invasive lesions. We recommend a similar treatment approach for osteofibrous dysplasia–like adamantinoma lesions.
Adamantinomas, however, are usually symptomatic, are highly invasive, have a high recurrence rate, and can metastasize.9 In these patients, a wide en bloc resection or amputation should be performed as soon as possible.11 Our case highlights that osteofibrous dysplasia–like adamantinoma lesions can occur in children and can remain stable, especially over the short term. Such lesions can be observed without surgical intervention.
