The clinical history and figures are consistent with a diagnosis of adamantinoma. This is best treated initially by en bloc resection with wide margins followed by appropriate reconstruction to prevent local recurrence or metastasis.
Differentiating between adamantinoma (AD) and osteofibrous dysplasia (OFD) can be difficult, as the two lesion share many similar characteristics. AD is a rare, low-grade malignant primary bone tumor that occurs most often in the tibia and/or fibula of adolescent persons and young adults; however, it has been reported in other long bones, as well. Histologically, AD is composed of islands of epithelial cells in a spindle-cell stroma and nuclear atypia with mitotic figures may be present as well. OFD is a rare, benign, fibro-osseous lesion that typically is seen within the cortex of the tibia in children. Microscopically, OFD is characterized by a loose, often storiform fibrous background containing spicules of woven bony trabeculae that are lined by a layer of osteoblasts. Treatment of OFD in children usually consists of observation.
Kashima et al. assessed expression of podoplanin, a glycoprotein found in osteocytes, in OFD and AD as well as in fibrous dysplasia and metastatic cancer. Podoplanin expression was found in OFD and AD only, and the authors concluded that expression of podoplanin in an osteolytic tumour of the tibia may be useful as a diagnostic discriminant in distinguishing OFD from fibrous dysplasia and ALB from metastatic adenocarcinoma.
Most et al. completed a review article discussing the features associated with OFD and AD. They state that management of OFD varies from observation to surgical intervention, depending on the age of the patient and the extent of the lesion. Management of AD requires surgical resection with wide margins, followed by appropriate reconstruction, to minimize the risk of local recurrence or metastasis.
Figure A shows a lateral radiograph of a tibia with multifocal lytic lesions and areas of intervening sclerosis, which can give a “soap bubble” appearance. Figures B and C show the characteristic histological findings of AD including islands and cords of basaloid epithelial cells in a fibrous stroma with nuclear atipias and mitotic figures.
Illustration A shows an example of OFD for comparison. Note the classic intracortical anterior tibial lesion which is well marginated and surrounded by an area of sclerosis. Illustration B demonstrates the histology of OFD, showing a loose, storiform fibrous background containing spicules of woven bony trabeculae that are lined by a layer of osteoblasts.
Answer 1: Observation would be appropriate for a diagnosis of OFD in a child.
Answer 2: Radiation and chemotherapy are not effective treatments for adamantinoma.
Answer 3: Bracing would be appropriate treatment for OFD in the setting of tibial bowing or pending pathologic fracture.
Answer 4: Above the knee amputation would be appropriate as a salvage operation if en bloc resection and reconstruction failed.
Kashima TG, Dongre A, Flanagan AM, Hogendoorn PC, Taylor R, Athanasou NA. Podoplanin expression in adamantinoma of long bones and osteofibrous dysplasia. Virchows Arch. 2011 Jul;459(1):41-6. Epub 2011 Apr 16. PubMed PMID: 21499851
PMID:21499851 (Link to Abstract)
Most MJ, Sim FH, Inwards CY. Osteofibrous dysplasia and adamantinoma. J Am Acad Orthop Surg. 2010 Jun;18(6):358-66. Review. PubMed PMID: 20511441.
PMID:20511441 (Link to Abstract)