Osteofibrous dysplasia is a benign fibro osseous process involving cortex
It occurs mostly in tibia and less commonly in fibula. Rarely can occur in forearm bones
Cytogenetics
Extra copies of chromosome 7,8,12 or 21 or their combinations may be present in Osteofibrous dysplasia and Adamantinoma
It has been hypothesized that Osteofibrous dysplasia with expansion of abnormal clone and additional structural chromosomal abnormalities will lead to development of Adamantinoma
Clinical presentation
Seen in young children in the first decade of life. The lesion behaves in aggressive fashion
Aggressiveness decreases as the child gets older
Patient presents with anterior bowing of tibia or pathological fracture
Imaging studies – Lesion involves the anterior cortex either of diaphysis or the metaphysis of tibia and presents as long lucent lesion which is surrounded by sclerosis
Gross – It is well demarcated white firm and fibrous lesion involving outer aspect of cortex
Microscopy
Features are similar to fibrous dysplasia having irregular bone trabeculae and interstitial fibrous stroma with collagen (hypocellular spindle cell stroma)
However in contrast to fibrous dysplasia, bone spicules are lined by osteoblasts that may produce a rim of lamellar bone, and the centre of the spicule has woven bone appearnce.
Foci of haemorrhage, foamy histiocytes and occasional cartilaginous areas may be observed
Few foci shows clusters of keratin positive cells showing keratinization because of which the term differentiated adamantinoma is applied
Treatment
Conservative approach as lesions regress with maturation of skeleton
References
K.Krishnan Unni, Carrie Y.Inwards, Julie A.Bridge, Lars-Gunnar Kind blom, Lester E. Conditions that simulate primary neoplasms of bone. In: Tumors of the Bone and joints. AFIP Atlas of Tumor Pathology. Series 4;Chapter 14:2005;321-382
Lauren Vedder Ackerman, David C. Dahlin. Fibrous tumros and Tumor like conditions. In: Orthopaedic Pathology (5th edition) by Peter G. Bullough 2004.Chapter 18:429-448