Zebra XXV, Part 2

JOURNAL OF ENDODONTICS Copyright © 2002 by The American Association of Endodontists

Printed in U.S.A. VOL. 28, NO. 6, JUNE 2002

ZEBRA HUNT Zebra XXV, Part 2 Antonio Scarano, DDS, Susanna Annibali, MD, DDS, Roberto Pippi, MD, DDS, Luciano Artese, MD, and Adriano Piattelli, MD, DDS

FIBROUS DYSPLASIA

In the last issue of the Journal of Endodontics, the case of a 32-year-old man with expansion of the jaw was presented. A panoramic radiography showed a 5-cm radiolucent lesion in the right mandible that extended posteriorly to the mandibular angle (Fig. 1). Radiopaque foci were present inside the radiolucency; no septa were present. The margins of the lesion were well defined. No resorption of the roots was present. No embedded tooth was present within the radiolucency. A computed tomography scan demonstrated that there was a spherical swelling of the inferior portion of the mandible (Fig. 2), and the cortical bone seemed to be thinned in some areas, whereas it was sclerotic in other areas. No infiltration or perforation of cortical bone was present. No pain was present, and jaw expansion with facial asymmetry was present. The following pathologies were suggested in the differential diagnosis: fibrous dysplasia, cemento-ossifying fibroma, adenomatoid odontogenic tumor, calcifying epithelial odontogenic tumor.

This is a lesion formed by the replacement of normal bone by fibrous connective tissue and weak fibrillar bone. Histologically, it is possible to observe numerous short, irregularly shaped trabeculae of woven bone. It may be limited to one bone (monostotic); this is the most common form (approximately 70%) and is the type that most often involves the jaws or it may involve several bones (polyostotic). The polyostotic form is usually found in children younger than 10 yr, whereas the monostotic type affects individuals in a slightly older age group. Fibrous dysplasia involves the maxilla almost twice as often as the mandible, especially in the posterior region. Fibrous dysplasia is a self-limiting, slow-growing process, starting in childhood. Swelling is usually unilateral and asymptomatic, with the growing of the lesion, facial asymmetry becomes evident and may be the initial presenting complaint. Radiographically, fibrous dysplasia has ill-defined margins with no

FIG 1. Panoramic radiography. A 5-cm lesion (arrows) with well-defined margins and radiopaque foci is present. 482

Vol. 28, No. 6, June 2002

Zebra Hunt

483

FIG 2. Computed tomography scan. The lesion produces a spherical swelling (S) of the mandible. The cortical bone is expanded but not perforated.

sharp line of demarcation and blends into surrounding bone without evidence of a circumscribed bone lesion. The lesions are usually unilateral, and they may be more radiolucent, more radiopaque, or a mixture of these two types. Fibrous dysplasia typically has the appearance of a diffusely radiopaque lesion, varying from a ground glass appearance to sclerotic. The lesion produces a fusiform or elliptical jaw expansion. Fibrous dysplasia rarely resorbs teeth. CEMENTOOSSIFYING FIBROMA The characteristics of this lesion are more like those of a tumor than a bone dysplasia. It is an infrequent lesion that occurs as a lesion with well-defined borders, and it presents a mixed radiolucent-radiopaque density depending on the amount of calcified material. The most common location is in the premolar-molar mandibular region. The lesions are usually slow-growing, solitary, can reach a size of up to 4 cm, and tend to expand the jaw; the lesion produces a roughly nodular or spherical jaw expansion. Bony trabeculae of varying sizes and consisting of lamellar woven bone occur. It is found usually in young adults (third to fourth decades), and females are slightly more affected. The disease is most often asymptomatic and only occasionally does facial asymmetry develop. Most lesions are discovered during routine clinical examination. Characteristically, the outer cortical bone is displaced and thinned but remains intact, and it is not infiltrated and perforated. The roots of teeth may be displaced and less commonly may be resorbed. Its differentiation from fibrous dysplasia can be very difficult. Both lesions show similar clinical, radiographic, and microscopic features. The great variation in mineralized material (woven bone, lamellar bone, and cementum-like spheroids) may make it possible to differentiate this lesion from fibrous dysplasia. The margins of cemento-ossifying fibroma are usually better defined, and these lesions occasionally have a soft tissue capsule, whereas fibrous dysplasia tends to blend with surrounding bone,

and at the time of surgery, the lesion is easily curetted or enucleated from surrounding bone. In fibrous dysplasia, the lesions may be more homogenous and show less variation.

ADENOMATOID ODONTOGENIC TUMOR Approximately 70% occur in the second decade, with an average age of 16 yr. There is a 2:1 female predilection. Approximately 75% of the lesions are located in the maxilla, usually the incisorcanine-premolar region. It has the appearance of a pericoronal cystlike radiolucency, which is similar to a follicular cyst, and usually surrounds an entire tooth. Often (in approximately two thirds of cases) radiopaque foci are present within the lesion. In some cases, it is possible to observe dense clusters of radiopaque foci similar to small pebbles.

CALCIFYING EPITHELIAL ODONTOGENIC TUMOR The mean age of presentation is 40 yr. A characteristic feature is the presence of radiopaque foci in close proximity to the crown of an unerupted tooth. These foci show a variation in size and density. The mandible is affected twice as often as the maxilla, and the tumor is located in the molar region of the mandible. The molar region of the maxilla and the premolar region of the mandible are the next most common sites. The tumor may expand the jaw but usually is discovered during a routine radiographic examination. The tumor may be unilocular or multilocular.

DISCUSSION Based on the above descriptions of the signs and symptoms of the various possibilities, the best clinical guess of what this lesion

484

Scarano et al.

Journal of Endodontics

FIG 3. It is possible to observe a fibrous connective tissue composed by spindled cells (arrow) organized in parallel bundles. H&E ⫻40.

FIG 4. Islands of mineralized material similar to cementum (arrow) are present within the connective tissue. H&E ⫻40.

may be is fibrous dysplasia or cemento-ossifying fibroma with a preference for the latter. This is based on the fact that cemento-ossifying fibroma usually affects the third and fourth decades, whereas fibrous dysplasia affects the first and second decades. Cemento-ossifying fibroma favors the body of mandible, whereas in fibrous dysplasia, the maxilla is slightly favored. Cemento-ossifying fibroma has welldefined margins, whereas fibrous dysplasia presents poorly defined margins; cemento-ossifying fibroma also shows a roughly nodular or spherical jaw expansion, whereas in fibrous dysplasia, the expansion is fusiform or elliptical. While the patient was under local anesthesia, a biopsy of the lesion was taken. The microscopy evaluation showed the presence

of a fibroblastic stroma with islands of calcified material (Figs. 3 and 4). The definitive pathologic diagnosis was cemento-ossifying fibroma.

Dr. Scarano is research fellow, and Dr. Artese is associate professor, Department of Pathology, Dental School, University of Chieti, Chieti, Italy. Dr. Annibali is associate professor, Department of Oral Surgery, and Dr. Pippi is researcher, Dental School, University of Rome “La Sapienza,” Italy. Dr. Piattelli is professor, Department of Oral Medicine and Pathology, Dental School, University of Chieti, Chieti, Italy and Honorary Senior Lecturer, Eastman Dental Institute for Oral Health Care Sciences, London, United Kingdom. Address requests for reprints to Dr. Adriano Piattelli, Via F Sciucchi 63, 66100 Chieti, Italy.