Year : 2010 | Volume
: 53 | Issue : 1 | Page : 122--124
Mixed odontogenic tumor: Ameloblastoma and calcifying epithelial odontogenic tumor
Demet Etit1, Mehmet Ali Uyaroglu1, Nezahat Erdogan2,
1 Ataturk Research and Training Hospital, Pathology, Turkey
2 Ataturk Research and Training Hospital, Radiology, Turkey
2040 Sok. Pamukkale 6. Blok 102. Giris Daire: 3 Mavisehir, 35540, Izmir
Odontogenic tumors constitute a group of heterogeneous disease derived from epithelial, mesenchymal and/or ectomesenchymal elements. Ameloblastoma is the best known and the most frequent form of odontogenic tumors. Calcifying epithelial odontogenic tumor (CEOT), known as Pindborg tumor, is locally invasive lesion which has a characteristic amiloid deposition. Here a case of a peripheral ameloblastoma associated with CEOT is presented with clinical and morphological features.
|How to cite this article:|
Etit D, Uyaroglu MA, Erdogan N. Mixed odontogenic tumor: Ameloblastoma and calcifying epithelial odontogenic tumor.Indian J Pathol Microbiol 2010;53:122-124
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Etit D, Uyaroglu MA, Erdogan N. Mixed odontogenic tumor: Ameloblastoma and calcifying epithelial odontogenic tumor. Indian J Pathol Microbiol [serial online] 2010 [cited 2021 Jan 26 ];53:122-124
Available from: https://www.ijpmonline.org/text.asp?2010/53/1/122/59201
Odontogenic tumors are derived from the epithelium and/or connective tissues associated with the formation of teeth, that is, from the enamel organ. Tooth formation is complicated, correspondingly microscopic features of odontogenic tumors are also complex. The group of lesions that have traditionally been considered as odontogenic tumors contain not only true neoplasms but also hamartomas and dysplastic conditions. Most odontogenic tumors are benign, intraosseous lesions. Some, however, are locally invasive. Peripheral odontogenic tumors are located in alveolar structures and gingiva. These are identical lesions with intraosseous counterparts.  Ameloblastoma is the most frequently seen epithelial odontogenic tumor. A calcifying epithelial odontogenic tumor (CEOT) which is often referred to as Pindborg tumor is rare than the ameloblastoma. It is a locally invasive tumor much similar to the classical intraosseous ameloblastoma. Both tumors are seen mostly in the fourth and fifth decades with no gender predominancy. They are localized generally in mandibula. ,
A 62-year-old female patient complained of a mass on her left gingivobuccal region which had been diagnosed as a benign odontogenic tumor at another center by a punch biopsy. On physical examination, the patient was edentulous. There was a mass on her left upper maxillary arcus which was eroding the overlying mucosa and had a diameter of 3 cm; there was no palpable lymhadenopathy on the head and neck region. Axial and coronal computerized tomography revealed a destructive mass of a diameter of 25 mm, involving the right maxillofacial junction [Figure 1].
The mass was totally excised and the cavity of the maxillary sinus was curatted. The cut surface of the specimen had solid appearence with a grayish white color. Microscopically the surface epithelium was ulcerated. The tumor consisted of islands of odontogenic epithelium within a mature connective tissue stroma. The basal cells of these islands exhibited nuclei which formed a palisade-like arrangement. The cytoplasms of the central stellate was generally vacuolated and the nuclei were located at the distal ends of the cells configuring a reverse polarization [Figure 2]. Besides these ameloblastoma areas, we observed dispersed islands consisting of other types of epithelial cells which exhibited well-defined cell outlines with bland nuclei. There was an eosinophylic amyloid-like material within these areas [Figure 3]. The amyloid-like material stained positively in crystal violet and a birefringence occured under polarized light in Congored stain. Necrosis and calcification were not seen.
The odontogenic tumors are derived from the enamel organ. Some arise from tissues of the functional enamel organ, others from remnants of that structure after the tooth has formed.  The complicated nature of this progression not surprisingly exists in the microscopy of the odontogenic tumors and their classification. Complex terminology of the odontogenic tumors has not changed in the 2005 World Health Organisation (WHO) classification.  In WHO classification, there are two general categories, one is benign and the other is malignant. There are separate subcategories depending on whether there is epithelium or ectomesenchium or both. For practical purposes the benign odontogenic tumors may be separated into three parts: epithelial, mesenchimal, both components exhibiting tumors.  Most odontogenic tumors are intraosseous lesions. A few occur on the gingiva or in the alveolar process and do not involve underlying bone.  The lesion of this case was located on the gingiva and the curattage specimen from the bone cavity was tumor free. The best known and the most frequently seen epithelial odontogenic tumor is ameloblastoma. ,, Although subtypes of ameloblastoma are described, the common point of these subtypes is the existence of the cell arrangement over proliferating nests resembling the organ of the enamel's ameloblasts. In the center of these nests there are also cells resembling the enamel's reticulin, loosely arranged stellate cells. ,, We observed cells with hypercromatic nuclei which had cytoplasmic vacuolation. The nuclei were located in the counter-side of the basal membrane. These palisade-like cells were in a mature connective tissue. There was a loosely arranged reticular stroma in the centre of the islets. These areas were evaluated as a typical ameloblastoma.
The CEOT or Pindborg tumor is composed of polyhedral epithelial cells with scanty stroma. The closely packed cells demonstrate nuclear pleomorphism. Variable amounts of an homogenous material is seen. This has been shown to be amyloid or a similar substance. ,, However, calcification is an important feature and sometimes it cannot be seen. In some cases clear cell nests may be observed. ,,, The first two features are necessary for the diagnosis. We observed, especially in the peripheral areas of the tumor, the polyhedral shaped cells with eosinophilic cytoplasm which demonstrated mildly nuclear anisomorphism. Amyloid was seen around these haphazardly arranged cells. We did not observe any calcification neither histologically nor radiologically. The CEOT-like areas were less than 25% in the total tumor's field.
Examples of combined or hybrid odontogenic tumors including CEOT and adenomatoid odontogenic tumor (AOT) have been reported in the literature. ,, The common point of these cases is that the predominant component was AOT and behaved similar to AOT. This is the reason why some authors do not accept this as a true combined tumor. They accept it only as AOT, including the CEOT-like areas. In the only article of a case, a combination of hybrid tumor as ours; CEOT and ameloblastoma, has been reported with a disease free span in five years.  This current patient remained tumor-free in a 25 months follow-up.
Considering the complicated nature of odontogenic tumors and a very rare case of this combination we met, we presented this hybrid tumor 'a mixed odontogenic tumor' to remind us that the term 'mixed' sometimes can be used to express a degree of confusion.
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