The cement-osseous dysplasia is considered as a non-neoplastic fibro-osseous lesion wherein bone is replaced by fibrous connective tissue along with the cemental masses and is categorized into three different entities, such as periapical, focal and florid. However, now the COD term has been replaced as osseous dysplasia in the recent WHO classification and is believed that the three entities represent a spectrum of lesions appearing to be reactive in nature and have differences only in clinical and radiological presentation. Histologically, it appears to affect the tooth-bearing areas probably derived from the periodontal ligament and from the cementum or cemental-like tissues.[7
The periapical osseous dysplasia appears as a radiolucent area at the apices of the anterior teeth and with time, the mineralization becomes radiopaque[2
] and rarely exceeds more than 1 cm,[7
] remaining relatively asymptomatic. The focal COD appears to arise at the previous extraction site or at the apices of the molar region, rarely exceeding 2 cm in diameter, with similar radiological presentation as that of the periapical osseous dysplasia. Both these variants may involve a single area or multiple areas in a quadrant. If there is symmetrical presentation affecting more than one quadrant, then the diagnosis of FCOD is considered.[7
] If there is a familial basis to the florid-osseous dysplasia, the familial gigantiform cementoma can be considered.[2
Although histopathology will remain similar for all the types, as this represents a spectrum of lesion rather than an entity,[7
] the early lesion represents cellular fibrous tissue containing trabeculae of woven bone with cementum-like calcification.[7
] With maturation, the ratio of fibrous tissue to mineralized materials are decreased and trabeculae become more curvilinear structures[1
] that progress to the radiopaque stage in which the cementum-like tissue coalesce to form large basophilic calcification with resting and reversal lines.[1
] There could be some difference in stage or degree of calcification, which will be in hand with radiological presentation. In the present case, the maxillary right quadrant resembled the most mature lesion, with large basophilic cemental masses  resembling a radiopaque stage, whereas the maxillary left and mandibular left quadrant resembled early to mature stages of lesion [Figures , and ], with a difference in the degree of calcification, which was evident as radiopacities in the radiograph .
The diagnosis of COD is a challenge, especially when it shows the cortical plate enlargement along with mixed radiopacities, as seen in the present case, in relation to the maxillary right quadrant [Figures and ] and may resemble Pagets disease of bone. Thus, Paget’s disease of bone may remain as differential diagnosis for COD[1
] and has to be ruled out as the former may transform into osteosarcoma.[1
] The dysplastic lesion of Paget’s is always polyostotic[10
] and because this case did not show an increase in the serum alkaline phosphatase level and in histopathology, there was no jigsaw puzzle or mosaic pattern of trabeculae seen, ruling out Paget’s disease. The second most common lesion that interfered with the diagnosis of COD was the fibrous dysplasia.[12
] However, fibrous dysplasia exhibits a ground glass pattern rather than a cotton wool appearance and histopathology of the specimen tissue exhibited irregular basophilic globular cemental masses that are not seen in fibrous dysplasia. Hence, the possibility of fibrous dysplasia could be ruled out.
The present case showed connective tissue fibers as filling material between the trabeculae, which may resemble chronic sclerosing osteomyelitis.[10
] Sequestra and periosteal bone formation were absent in the radiological picture. There was no clinical history of pain or pus drainage nor evident sinus tract in relation to the lesional site. The histopathology of the lesional tissue does not show areas of abscess formation, ruling out the possibility of chronic sclerosing osteomyelitis.
The histopathology of COD most commonly resembles cemento-ossifying fibroma.[1
] Cemento-ossifying fibroma, although not always, shows characteristic connective tissue capsule surrounding the lesional tissue, but is well demarcated grossly and microscopically and therefore is most often received as intact specimen.[1
] But, the COD is received as multiple bits as it is not demarcated from the surrounding bone. Because the biopsy specimen of the present case was received in multiple bits, it is in accordance with gross picture of COD. The trabeculae and cemental masses in cemento-ossifying fibroma most commonly blend with that of connective tissue whereas in case of COD, the trabeculae or the cemental masses will be retracted from the surrounding connective tissue,[1
] which is also seen in this case. Therefore, the diagnosis is less likely to be cemento-ossifying fibroma.
Because this case demonstrated impaction of permanent premolars in the maxillary left and mandibular left quadrants, the possibility of Gardner’s syndrome has to be questioned as earlier reports suggested misdiagnosing Gardner’s syndrome as COD.[10
] However, as skeletal, skin manifestations and intestinal polyps of Gardner’s syndrome were not seen, it eliminates the possibility of Gardner’s syndrome.
The mandibular left quadrant showed radiopacity in relation to the apex of the root surface of the retained deciduous molar. However, the received specimen did not show any attachment to the apex of the root, a feature of cementoblastoma.[6
] The present case demonstrated the cemento-osseous tissue with the absence of fusion to the apex of the tooth root, which rules out the possibility of cementoblastoma.
In addition, the mandibular left quadrant also showed unilocular radiolucency that resembled a dentigerous cyst in histopathological findings. However, earlier reports suggested FCOD in association with simple bone cyst,[2
] which exhibits a cystic cavity not lined by a cystic epithelium. As the present case consisted of cystic lining epithelium, the possibilities of it being simple bone cyst are ruled out. To our review, this is the first case of FCOD with cystic lining epithelium to be reported.