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The lesion has a zonal architecture with a center of immature bone surrounded by more mature lamellar bone. The central spicules of woven bony trabeculae are lined by a layer of osteoblasts. The backgound is a loose and storiform fibrous tissue. | The lesion has a zonal architecture with a center of immature bone surrounded by more mature lamellar bone. The central spicules of woven bony trabeculae are lined by a layer of osteoblasts. The backgound is a loose and storiform fibrous tissue. | ||
* | Notes: | ||
** | *The diagnosis depends on the ratio of fibrous to epithelial tissue which can vary within each particular tumour. | ||
* | **Due to the above ample tissue is required for accurate histologic diagnosis. | ||
** | *Current discussion regarding the definition of an OFD-like adamantinoma. | ||
**As of 2010, WHO requires absence of keratin-positive cells for OFD. | |||
**Some accept as OFD lesions with scattered isolated keratin positive spindled cells. | |||
**Gray zone and varying interpretations of the boundry of OFD, OFD-like adamantinoma and adamantinoma. | |||
DDx: | |||
* | *[[Adamantinoma]] - epithelial elements are prominent and atypical. | ||
*OFD-like [[adamantinoma]] - see below. | |||
*[[Fibrous dysplasia]] - bony trabeculae lack osteoblastic rimming, not zonal. | |||
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===Images=== | ===Images=== |
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