Updated Classification Schemes for Fibro-Osseous Lesions of the Oral & Maxillofacial Region: A Review <s> I. Introduction <s> Summary A series of 30 fibro-osseous jaw lesions was evaluated for histological parameters that enable appropriate diagnostic classification. Special emphasis was laid upon the histomorphology of the lesion-jawbone interface, blending of lesional bone with adjacent jawbone being employed as the decisive factor in distinguishing between fibrous dysplasia and other fibro-osseous jaw lesions. Using this feature as a discriminative tool, other histological aspects that were useful in differential diagnosis could be identified. Fibrous dysplasia (n=11) shows a rather uniform appearance with a constant ratio bone: fibrous tissue throughout the entire lesion; acellular mineralized particles are virtually absent. Juvenile ossifying fibroma (n=3) is characterized by a highly cellular fibroblastic stroma and garland-like strands of cellular osteoid. Ossifying fibroma (n=12) shows a high variability in stromal cellularity and types of mineralized material. Localized periapical fibro-osseous cemental lesions (n=4) are histologically almost similar to ossifying fibroma although more heavily mineralized. It is concluded that there is full agreement between histology and radiology in indicating whether a fibro-osseous jaw lesion is demarcated or blends into its surroundings. Moreover, an appropriate diagnosis can be reliably made on histological grounds. <s> BIB001 </s> Updated Classification Schemes for Fibro-Osseous Lesions of the Oral & Maxillofacial Region: A Review <s> I. Introduction <s> Maxillofacial fibro-osseous lesions (FOL) consists of lesions that differ, with the exception of fibrous dysplasia, to those found in the rest of the skeleton. FOLs of the face and jaws are cemento-osseous [corrected] dysplasia, fibrous dysplasia and cemento-ossifying fibroma. Radiology is central to their diagnosis because the pathology for all FOLs is similar, although they range widely in behaviour, from dysplasia, hamartoma to benign neoplasia with occasional recurrence. Furthermore, once diagnosed the management of each is different. For cemento-ossifying dysplasia, this may mean doing nothing, simply because no treatment is generally appropriate. Almost all cemento-osseous [corrected] fibromas should be treated surgically, whereas cases of fibrous dysplasia are treated according to their clinical presentation, ranging from review and follow-up to surgery necessary to save the patient's sight or reduce deformity. The most important and frequent features of the FOLs differential diagnosis is discussed with assistance of a flow-chart. <s> BIB002 </s> Updated Classification Schemes for Fibro-Osseous Lesions of the Oral & Maxillofacial Region: A Review <s> I. Introduction <s> Summary Fibro-osseous lesions are a poorly defined group of lesions affecting the jaws and craniofacial bones. All are characterized by the replacement of bone by cellular fibrous tissue containing foci of mineralization that vary in amount and appearance. Classification and, therefore, diagnosis of these lesions is difficult because there is significant overlap of clinical and histological features. The group includes developmental and reactive or dysplastic lesions as well as neoplasms. Recently a new terminology has emerged that has culminated in the latest WHO classification. The core of this classification is the concept of a spectrum of clinicopathological entities in which the diagnosis can only be made on the basis of a full consideration of clinical, histological and radiological features. This review will describe the salient features of these lesions in an attempt to provide practical guidance for the surgical pathologist. <s> BIB003
Fibro-Osseous lesions [FOL] are a group of lesions which are known to affect the jaws and the craniofacial bones which is regarded as very confusing area in diagnostic pathology . The term refers to a diverse process in which the normal architecture of bone is replaced by fibrous tissue containing varying amount of foci of mineralization. BIB003 These group of lesions are known to encompass common characteristics that include common clinical, radiographic and microscopic features. Most of these lesions are of unknown aetiology, while some lesions are believed to be neoplastic while others are related to metabolic disturbances and are also believed to cause considerable diagnostic challenges. [2] While some of the FOL are believed to be true neoplasms having a considerable potential for growth if not fully excised , the peculiar anatomic location of these craniofacial lesions can result in conditions like encephalitis and sometime meningitis which are considered fatal.  Histologically , these group of FOL are characterised by the replacement of normal bone by fibrous connective tissue matrix. The fibrous tissue displays variable features like varying degree of mineralization in the form of woven bone or cementum like basophilic structures which are indistinguishable from cementicles.  Classification Schemes of Fibro-Osseous Lesions The various Classifications systems proposed by authors are enumerated as below.  BIB001 In 1990 Peiter. J. Slootweg & Hellmuth Muller gave a classification that laid emphasis primarily on the histopathological features, and they underscore that this classification requires inclusion of adjacent normal bone to make diagnosis. However in the absence of this, the clinical & radiological features have to be taken in to consideration.  But the identification of identical cementum like tissues in lesions in extra-gnathic sites suggested that this tissues may be a merely normal variant of bone, and that dental cementum itself is a specialized form of "bundle-bone". Therefore, in the second edition of the who's classification in 1992, three of the "cemental" lesion were transferred to the "neoplasm and other tumors related to bone "group, leaving the benign cementoblastoma as the sole true neoplasm of dental cementum. BIB002 This second edition of the WHO Histological Typing of odontogenic tumors in 1992 recognized them as the group of cement-osseous dysplasia which included "florid cement-osseous dysplasia" that form with "Periapical cemental dysplasia" & "other cemento-osseous dysplasia" [ 