Pathology of the Head and Neck

Maxillofacial Skeleton and Teeth Chapter 4 123Fig. 4.33. Psammomatoid ossicles in a cellular stroma characterisejuvenile psammomatoid ossifying fibroma. A comparison withFig. 4.30 shows that these particles are not as smoothly outlined asthose occurring in conventional ossifying fibromasFig. 4.35. Osseous dysplasia typically lies at the root tip. It consistsof fibrous tissue containing mineralised material of varyingappearanceFig. 4.34. Thread-like calcifications in an eosinophilic matrix arealso often present in juvenile psammomatoid ossifying fibromathe psammomatoid ossicles in juvenile psammomatoidossifying fibroma are clearly different from the acellularspherical real psammoma bodies [172].Clinically, ossifying fibroma causes expansion of thebone involved leading to a palpable swelling. Radiographically,a demarcated lesion is seen that may haveradiodense as well as radiolucent areas depending onthe various contributions of soft and hard tissue componentsto an individual lesion [13].Excision of ossifying fibromas usually yields a permanentcure.in areas similar to an aneurysmal bone cyst, multinucleategiant cells, and mitotic figures can also be observed.Juvenile psammomatoid ossifying fibroma hasthe bony walls of the paranasal sinuses as site of predilection[179].Ossifying fibroma may be confused with fibrous dysplasia.The most important distinguishing feature is thepresence of demarcation and/or encapsulation in ossifyingfibroma as opposed to the merging with its surroundingsas shown by fibrous dysplasia. In addition,the variation in cellularity as well as in appearance ofmineralised material distinguishes ossifying fibromafrom fibrous dysplasia. To distinguish ossifying fibromafrom osseous dysplasia, data on clinical presentationand radiographic appearance are indispensable (seeSect. 4.5.3).Juvenile psammomatoid ossifying fibroma has to bedifferentiated from meningioma with psammoma bodies;immunohistochemistry positive for EMA rules outjuvenile psammomatoid ossifying fibroma. Moreover,4.5.3. Osseous DysplasiaICD-O:9272/0Osseous dysplasia is a pathologic process of unknownaetiology located in the tooth-bearing jaw areas in thevicinity of the tooth apices and is thought to arise fromthe proliferation of periodontal ligament fibroblaststhat may deposit bone as well as cementum. The conditionoccurs in various clinical forms that bear differentnames. However, all have the same histomorphology:cellular fibrous tissue, trabeculae of woven as well aslamellar bone and spherules of cementum-like material(Fig. 4.35). The ratio of fibrous tissue to mineralisedmaterial may vary and it has been shown that these lesionsare initially fibroblastic, but over the course ofseveral years may show increasing degrees of calcification.This variation in ratio of soft tissue to hard tissueis reflected in the radiographic appearance; lesions arepredominantly radiolucent, predominantly radiodenseor mixed.