This patients presentation, histology, and radiograph are consistent with a diagnosis of osteofibrous dysplasia(OFD). These lesions are most commonly found in the tibia of children within the first decade of life. Radiographs typically show a lytic lesion occurs in the anterior cortex of the diaphysis or metaphysis of the tibia which often causes anterior-posterior bowing. The tumor has a multi-loculated appearance and causes distortion of the thin cortex. Histologically, OFD consists of irregular spicules of trabecular bone lined by osteoblasts. These osteoblasts produce a rim of lamellar bone around centers of woven bone.
Most et al discuss the differences between OFD and AD, work-up, and treatment of these fibro-osseous lesions in their JAAOS review article.
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 was expressed in epithelial cells and tumour glands in AD and OFD, and was not expressed by in fibrous dysplasia or in metastatic adenocarcinoma. They concluded that the 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.
Figure A shows a lateral radiograph of a tibia with the classic appearance of OFD in the anterior tibial cortex. Figures B and C show a low and high power histology slide of OFD. The findings in these figures are significant for fibroblast proliferation surrounding islands of woven bone with osteoblastic rimming.
2-Nonossifying fibroma presents radiographically as a solitary well circumscribed lesion, and is usually found incidentally unless associated with a pathologic fracture. Histology shows dense fibroblasts in whorled and storiforrn patterns. An example is shown in Illustration A.
3-Osteoblastoma-A solitary, benign bone-forming tumor that occurs in the spine and long bones of young adults. Radiographic findings typically show a radio-lucent defect with a central density due to ossification. An example is shown in Illustration B.
4-Chondroblastoma-A rare benign tumor found in the epiphysis of long bones, usually of the lower extremity. Radiographs typically show a single lytic lesion with well defined margins. An example is shown in Illustration C.
5-Ewing's sarcoma-Ewing's sarcoma is often associated with a lamellated or "onion skin" periosteal reaction. Histology specimens consist of densely packed uniform small blue cells in sheets. The cells have scant cytoplasm without distinct borders. An example of Ewing's histology is shown in Illustration D.
Most MJ, Sim FH, Inwards CY. Osteofibrous dysplasia and adamantinoma. J Am Acad Orthop Surg. 2010 Jun;18(6):358-66. Review.
PMID:20511441 (Link to Abstract)
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. doi: 10.1007/s00428-011-1081-2. Epub 2011 Apr 16.
PMID:21499851 (Link to Abstract)