Pathology of the Head and Neck

124 P.J. Slootweg4Fig. 4.36. Central giant cell granuloma shows osteoclast-like giantcells in a loose fibrocellular stroma. Cherubism has an identicalappearanceOsseous dysplasia lacks encapsulation or demarcation,but tends to merge with the adjacent cortical ormedullary bone [13].The several subtypes of osseous dysplasia are distinguishedby clinical and radiological features. Periapicalosseous dysplasia occurs in the anterior mandible andinvolves only a few adjacent teeth. A similar limited lesionoccurring in a posterior jaw quadrant is known asfocal osseous dysplasia [167]. Florid osseous dysplasia isnon-expansile, involves two or more jaw quadrants andoccurs in middle-aged black females [13]. Familial gigantiformcementoma is expansile, involves multiplequadrants and occurs at a young age. This type of osseousdysplasia shows an autosomal dominant inheritancewith variable expression, but sporadic cases without ahistory of familial involvement have also been reported[1, 189]. Simple bone cysts may be seen with florid andfocal osseous dysplasia [59, 62].Osseous dysplasia has to be distinguished from ossifyingfibroma. Osseous dysplasia is a mixed radiolucent-radiodenselesion with ill-defined borders in thetooth-bearing part of the jaws, either localised or occupyinglarge jaw areas depending on the type. In contrast,ossifying fibroma is usually a localised lesion thatexpands the jaw, and is predominantly radiolucent withradiodense areas [164].Osseous dysplasia also has to be differentiated fromsclerosing osteomyelitis [140]. Sclerotic lamellar bonetrabeculae and well-vascularised fibrous tissue withlymphocytes and plasma cells define sclerosing osteomyelitis,whereas cementum-like areas and fibrocellularsoft tissue are lacking [53].The various forms of osseous dysplasia do not requiretreatment unless necessitated by complications such asinfection of sclerotic bone masses, as may occur in floridosseous dysplasia, or facial deformity, as may be seenin familial gigantiform cementoma.4.6 Giant Cell LesionsCentral giant cell granuloma , cherubism and aneurysmalbone cyst all show osteoclast-like giant cells lyingin a fibroblastic background tissue. The fibroblastic tissuemay vary in cellularity from very dense to cell-poor.Mitotic figures may be encountered but are usually notnumerous and not atypical. The giant cells mostly clusterin areas of haemorrhage, but they may also lie moredispersed among the lesion (Fig. 4.36). Bone formation,if present, is usually confined to the periphery of the lesion.Radiologically, all three types of giant cell lesionshave a lucent, quite often multilocular appearance. Multiplegiant cell lesions may occur in association withNoonan’s syndrome as well as with neurofibromatosis[38, 134]. Further discussion will only include giant cellgranuloma and cherubism as they are confined to thejaws.4.6.1 Central Giant Cell GranulomaCentral giant cell granuloma is mostly seen before theage of 30. The lesion is restricted to the jaws, the mandiblebeing more often involved than the maxilla. Its aetiologyis unknown. Lesions with a histologic appearanceidentical to that of the central giant cell granuloma mayoccur in the gingiva and are called giant cell epulis (seeChap. 3). Sometimes, lesions combine the appearanceof a giant cell granuloma with that of an odontogenicfibroma [108].Clinically, central giant cell granuloma manifests itselfas a localised jaw swelling. Radiographically, it is aradiolucent lesion that may be either uni- or multilocular.As the lesion is not encapsulated, removal is sometimesfollowed by recurrence. If there is recurrence, hyperparathyroidismshould be ruled out as the brown tumoursassociated with this latter disease are identical togiant cell granulomas. Also, distinction has to be madebetween giant cell granulomas and true giant cell tumours.There has been much discussion whether giantcell granulomas with more aggressive behaviour thanusually observed could represent a gnathic manifestationof this latter lesion [4, 163].4.6.2 CherubismIn cases of cherubism, two or more jaw quadrants containlesions histologically similar to giant cell granuloma.The disease occurs in young children, often with ahistory of other afflicted family members. The geneticdefect responsible for cherubism has been localised tochromosome 4p16.3 [112].The expansion of the affected jaw areas causes the angelicface leading to the lesion’s designation: cherubism.