Pictorial Essay. CT of Calcifying Jaw Bone Diseases

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1 Pictorial Essay CT of Calcifying Jaw one Diseases Koichi Yonetsu 1 and Takashi Nakamura Downloaded from by on 01/08/18 from IP address Copyright RRS. For personal use only; all rights reserved O dontogenic and nonodontogenic tumors and tumorlike lesions of the jaw bones constitute a wide spectrum of radiographic manifestations. Such an unusually wide range of radiographic manifestations may result from the fact that the jaw bones contain dental components of ectodermal Fig year-old boy with ameloblastic fibroodontoma of right maxilla., xial CT scan shows densely calcified mass (arrows) associated with impacted first molar tooth., Coronal CT scan shows maxillary sinus floor (arrows) expanded and lifted upward by tumor. Fig year-old girl with ameloblastic fibroodontoma in right mandible., xial CT scan shows loose calcified strands radiating from center to periphery of lesion, giving wheel-spoke appearance., Coronal CT scan shows involvement of second premolar tooth in osteolytic area (arrow ). and mesodermal origin such as enamel, dentin, cementum, and pulp tissues. In particular, calcifying jaw bone diseases are frequently associated with loose or dense calcifications, some of which are characteristic, although some are not. These calcification patterns have been extensively investigated with conventional radiography. However, CT features of calcifying jaw bone diseases have not been well documented. In this article, we display a panel of CT features of histologically proven benign calcifying odontogenic tumors and tumorlike lesions in the jaw bones to provide provisional information for diagnostic differentiation based on CT. Received January 15, 2001; accepted after revision pril 12, oth authors: Department of Radiology and Cancer iology, Nagasaki University School of Dentistry, Sakamoto, Nagasaki , Japan. ddress correspondence to T. Nakamura. JR 2001;177: X/01/ merican Roentgen Ray Society JR:177, October

2 Yonetsu and Nakamura Downloaded from by on 01/08/18 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old girl with adenomatoid odontogenic tumor in left maxilla., xial CT scan shows irregular calcification around impacted first premolar tooth. Root of canine tooth (arrow ) is also involved., Coronal CT scan shows that calcific deposits are confined to area around crown of impacted premolar tooth, which is completely involved with expansile lesion. C Fig year-old girl with calcifying odontogenic cyst in mandible., xial CT scan shows trace of calcification., xial CT scan at level of tooth roots shows speckled calcifications (arrows) in upper part of lesion. Canine and first and second premolar teeth are involved. C, Oblique conventional radiograph shows multilocular radiolucent area associated with speckled calcification in its periphery. 938 JR:177, October 2001

3 CT of Calcifying Jaw one Diseases Downloaded from by on 01/08/18 from IP address Copyright RRS. For personal use only; all rights reserved meloblastic Fibroodontoma meloblastic fibroodontoma is associated with varying degrees of inductive dental hard tissues such as enamel and dentin. The CT features depend largely on the amount of hard tissues present in the lesion, with the calcific density in the lesion varying from homogeneous masslike structures (Fig. 1) to multiple spots or striations (Fig. 2). This variation may be correlated with the tumor maturation. Even in patients with a large calcified mass, however, the radiolucent periphery of the lesion is unexceptionally retained [1] (Fig. 1). denomatoid Odontogenic Tumor n adenomatoid odontogenic tumor is commonly associated with an embedded tooth, and in such cases may radiographically simulate a dentigerous cyst. However, adenomatoid odontogenic tumors frequently extend beyond the cementoenamel junction Fig year-old woman with periapical cemental dysplasia., xial CT scan shows homogeneously calcified masses (arrowheads) surrounding root of first molar tooth (arrow )., Coronal CT scan shows noncalcified layer intervening between calcified mass (arrowheads) and root of adjacent tooth (arrow ). C, Panoramic radiograph shows well-demarcated osteosclerotic area adjacent to distobuccal cusp of mandibular first molar and mesiobuccal cusp of mandibular second molar (arrow ). and include the tooth root (Fig. 3), a feature rarely seen with dentigerous cysts. Calcification may be faint or extensive but is typically seen around an impacted tooth (Fig. 3). The cyst formation is not unusual, and calcified tissues may be present in the cyst wall. Calcifying Odontogenic Cyst Hard tissues may be laid down adjacent to the basal layer of epithelium to form a thin calcified layer on CT (Figs. 4 and 4C). In some instances, the cyst is associated with extensive hard-tissue formation resembling complex or compound odontoma (Fig. 4). Calcification may be seen around an impacted tooth, making differentiation from the adenomatoid odontogenic tumor difficult. Periapical Cementoosseous Dysplasia This nonneoplastic lesion affects periapical tissues of one or more teeth that are adjacent to one another or separately located in different parts of the jaw. Each lesion is self-limiting and rarely exceeds 1 cm in diameter [1] (Figs. 5 and 5C). In contrast to hypercementosis, each calcified mass is separated from the tooth root by a noncalcified layer (Fig. 5). Florid Cementoosseous Dysplasia Florid cementoosseous dysplasia exhibits multiple lobulated masses of cementoosseous hard tissue in the periapical and alveolar regions of multiquadrant parts of the jaw bones [1] (Fig. 6). The calcified tissues are distributed more or less symmetrically and may be associated with one or more simple bone cysts (Fig. 6). Each calcified mass may grow to a considerable size and may cause cortical expansion (Fig. 6), although such expansion is generally considered to be self-limiting. djacent hard-tissue masses may fuse to each other, but noncalcified zones between the tooth C JR:177, October

4 Yonetsu and Nakamura Downloaded from by on 01/08/18 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old woman with florid cementoosseous dysplasia in mandible., xial CT scan shows multiple discrete calcified masses in tooth-bearing regions of mandible. Expansile osteolytic area (simple bone cyst, arrows) is also noted in left premolar region of mandible., Reconstructed multiplanar CT scan (DentaScan TM; GE Medical Systems, Milwaukee, WI) shows spatial relationship between tooth roots and sclerotic areas. First and second incisor teeth, canine teeth, first and second premolar teeth, and first and second molar teeth are involved in sclerotic lesions. Osteolytic lesion appears in mandibular left parasymphasis. Fig year-old woman with cementoossifying fibroma in right mandible. xial CT scan shows large mass with varying degrees of calcification occupying entire body of mandible. Fig year-old boy with juvenile ossifying fibroma of left mandible., xial CT scan shows dominantly osteolytic area in angle of mandible. Expanded cortex is markedly disrupted. Note that dental sac margin of nonerupted second molar tooth (arrowhead ) is disrupted; compare with normal dental sac in opposite side., Reconstructed coronal CT image shows homogeneously sclerotic area below osteolytic focus. Mandibular canal (arrow ) is also seen in this sclerotic area. 940 JR:177, October 2001

5 Fig year-old boy with complex odontoma in left maxilla., xial CT scan shows homogeneously calcified mass (arrow ) associated with displaced first premolar tooth., Coronal CT scan shows calcified mass extruding into maxillary sinus. CT of Calcifying Jaw one Diseases Downloaded from by on 01/08/18 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old girl with compound odontoma in left maxilla. xial CT scan shows multiple toothlike structures (arrows) around impacted first molar tooth. Fig year-old girl with monostotic fibrous dysplasia in mandible. xial CT scan shows ground-glass appearance of enlarged left mandible. Margin between affected and intact parts is clear. Fig year-old girl with polyostotic fibrous dysplasia in maxilla., xial CT scan shows ground-glass appearance of maxilla, inferior nasal concha, and pterygoid process (sphenoid bone)., Coronal CT scan shows extensive involvement of bones (such as maxilla, zygoma, ethmoid, and temporal bones) and inferior nasal concha. Parietal bone is also involved. JR:177, October

6 Yonetsu and Nakamura Downloaded from by on 01/08/18 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old girl with lbright s syndrome. xial CT scan shows cystlike low-density areas (arrows) in relatively homogeneously sclerotic lesion of mandible. Fig year-old woman with osteochondroma of mandible. xial CT scan shows pedunculated mass growing from left mandibular angle. Surface of lesion is lined with thin layer of densely calcified compact bone. roots and hard-tissue masses are still intact even in such cases (Fig. 6). When the hard-tissue mass is fused to the roots, however, the diagnosis of hypercementosis should be considered. Cementoossifying Fibroma Craniofacial ossifying fibromas have two distinct entities: conventional and juvenile ossifying fibromas. Juvenile ossifying fibromas occur in young individuals and have a greater tendency to recur than the conventional type. conventional ossifying fibroma is well demarcated or encapsulated, as evidenced by histopathologic specimens. However, hard tissues on CT images are sometimes irregularly defined and diffusely calcified (Fig. 7). The aggressive nature of the juvenile ossifying fibroma is occasionally reflected by an abrupt loss of the overlying cortex (Fig. 8). Complex and Compound Odontomas Complex and compound odontomas are malformations in which all dental tissue components are involved. In complex odontomas, the hard tissues dentin, enamel, and cementum are arranged in disorder and, when they are densely packed, a homogeneous calcified mass appears on CT scans (Fig. 9). In contrast, in compound odontomas, more orderly patterns are evident so that the lesion appears to be associated with multiple calcified structures, each reminiscent of a tooth (Fig. 10). Fibrous Dysplasia Craniofacial fibrous dysplasias can be divided into three forms: monostotic fibrous dysplasia (Fig. 11), polyostotic fibrous dysplasia (Fig. 12), and lbright s syndrome (Fig. 13). Polyostotic fibrous dysplasia arises early in life, and each of Fig year-old man with torus palatinus. Reconstructed coronal CT scan shows highly calcified lobulated mass growing from palatal bone. Fig year-old man with torus maxillaris. xial CT scan shows dome-shaped protuberances of buccal cortex of maxilla. one marrow space is also bulging into lesion. 942 JR:177, October 2001

7 CT of Calcifying Jaw one Diseases Downloaded from by on 01/08/18 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old woman with tori of palatal bone, maxilla, and mandible., xial CT scan shows marrow formation in torus maxillaris., Three-dimensional CT image shows involvement of maxilla and palatal bone. C, xial CT scan shows symmetrical torus mandibularis composed of compact bone. the affected craniofacial bones appears to be involved independently of neighboring bones; consequently, the affected bones frequently show different levels of mineralization on CT images (Fig. 12). lbright s syndrome represents a separate entity of polyostotic fibrous dysplasia and is associated with cutaneous pigmentation ( cafe-au-lait spots) and precocious puberty. Histologically, fibrous dysplasias are characterized by fibrous connective tissue containing trabeculae of coarse woven bone and less organized lamellar bone [1]. These features give the characteristic ground-glass appearance on CT images and conventional radiographs. Mandibular involvement may yield a cystic pattern on CT images. In that case, a central osteolytic area may contain calcified densities (Fig. 13). However, in other craniofacial bones, the homogeneous sclerotic type of fibrous dysplasia is dominant. Infections spreading from the involved tooth of the mandible probably modify the radiographic manifestations. Osteochondroma Osteochondroma is suggested to arise from an overgrowth of cartilage and most frequently occurs in the coronoid and condylar processes [2], but other regions are not immune to the disease. This slow-growing tumor is composed of compact and cancellous bones that can be observed on CT scan if the bones are large enough (Fig. 14). Torus torus is a localized outgrowth of bone on the surface of the maxilla (torus palatinus or torus maxillaris) or mandible (torus mandibularis). Different from osteochondroma (or osteoma), a torus is usually composed of compact bone with homogeneous mineralization (Fig. 15), but some contain a marrow space and exhibit trabeculations [3] (Figs. 16 and 17). In the maxilla, a torus arises in the midline of the palatal bone, occasionally showing a pedunculated protuberance (Fig. 15). However, the torus may arise on the outer (Fig. 16) or inner (Figs. 17 and 17) surface of the maxillary alveolar bone. In the mandible, on the other hand, a torus arises from the inner surface of the mandible at the level above the mylohyoid line and is usually bilateral [3] (Fig. 17C). References 1. Kramer IRH, Pindborg JJ, Shear M. Histological typing of odontogenic tumours, 2nd ed. New York: Springer-Verlag, 1992: Westesson P-L, Katzberg RW. Temporomandibular joints. In: Som PM, Curtin HD, eds. Head and neck imaging, 3rd ed. St. Louis: Mosby, 1996: Weber F, Scrivani SJ. Mandible: anatomy, cysts, tumors, and nontumorous lesions. In: Som PM, Curtin HD, eds. Head and neck imaging, 3rd ed. St. Louis: Mosby, 1996: C JR:177, October