Kamis, 23 Desember 2010

Calcifying Epithelial Odontogenic Tumour (Pindborg's Tumour)

Calcifying Epithelial Odontogenic Tumour (CEOT) is a rare, benign odontogenic neoplasm which accounts for less than 1% of all odontogenic tumours . It was first described by the Dutch pathologist Jens Jorgen Pindborg in 1955. CEOT is also called as “Pindborg’s tumour” which, the term was introduced by Shafer et.al in 1963. It was previously described as an adenoid adamantoblastoma, unusual ameloblastoma and a cystic odontoma. The term ‘Calcifying Epithelial Odontogenic Tumour’ has been generally accepted and adopted by the WHO in 1971,7 J.J. Pindborg and I.R.H. Kramer, Histological typing of odontogenic tumors, jaw cysts and allied lesions, WHO, Geneva (1971). when it was recognized as a distinct entity.

The age range is wide 8-92 years, although it is most commonly seen in the fourth and fifth decade of life. CEOT may occur as intraosseous tumours or extra osseous tumours. The extraosseous variant is diagnosed slightly earlier (mean age 34.4 years) than the intraosseous type (mean age 38.9 years). They appear to be no sex predilection.

Mandible is more commonly affected than maxilla in ratio of 3:1 and it is usually located in the premolar and molar regions. When present in the maxilla, the CEOT is preferentially located in the posterior region. The prevalence in the molar region is three times that in the premolar region. CEOT with extension into the maxillary sinus is uncommon.

94% of the lesions are central and intraosseous and 6% are extraosseous.

Clinically, it presents as a slowly growing expansile jaw lesion, which may be associated with pain, nasal airway, obstruction, epistaxis and headache. Maxillary, tumors may present with facial alteration and proptosis. It may cause tooth tipping, migration, rotation and/or mobility secondary to tooth resorption. CEOT is often concurrent with an unerupted or impacted tooth (52 % of odontogenic tumours) and rarely associated with paresthesia.

An extraosseous variant of CEOT also presents clinically as a nodular mass on gingival mucosa in anterior tooth location, but this is extremely rare and only 10 cases are reported (5%).

CEOT has also been reported as hybrid tumours in combination with adenomatoid odontogenic tumour which has been reported to be frequent in women and present at younger age.

Depending on stages of development, CEOT may present variable radiographic appearances. The lesion usually consists of a radiolucent area, which is well defined. Area is often unilocular when small and larger lesions tend to have multilocular, honeycomb or soap bubble appearance. Multiple radiopacities of varying size may develop within the radiolucent area and occasionally there extensive areas of calcification that cause the lesion to become radiopaque. The mixed radiolucent and radiopaque pattern occurred most often (65%) followed by the completely radiolucent pattern (32%) and least often the totally radiopaque ‘‘wind driven snow’’ pattern (3%). When tumour is associated with impacted tooth, it may appear as pericoronal radiolucency with or without small radiopacities.

The two commonest presentations were found to be pericoronal radiolucency with diffuse radiopacities in a radiolucent area. This makes the clinical diagnosis somewhat difficult due to the similarity with dentigerous cyst. For extraosseous CEOT, bone adjacent to the tumour shows a superficial erosive pattern.

The clinical differences among the CEOT types have been thought to be attributed to their origin. It has been shown that the intraosseous CEOT is derived from the stratum intermedium of the enamel organ. In contrast the extraosseous form arises from the dental lamina rests in gingiva and/or basal cells of gingiva surface epithelium, but today most investigators believe that the tumour cells originate from the stratum intermedium of the normal dental germ. This idea is based on the morphologic similarity of the tumour cells to the normal cells of the stratum intermedium and on the finding of high activity of alkaline phosphatase and adenosine triphosphate at both sites.

When it comes to the hybrid tumour between CEOT and adenomatoid odontogenic tumour (AOT), It had been postulated that the AOT portion arise from all three components of the enamel organ (Preameloblast, Stellate reticulum, Stratum intermedium).

According to the literature, the characteristic histologic criteria for the diagnosis of CEOT are sheets of large polygonal epithelial cells that have well defined borders and often show prominent intercellular bridges. There is usually pleomorphism of the epithelial cells. Nuclei are often prominent and show considerable variation in size, shape and number. Cellular abnormalities are frequent, whereas mitotic figures are rarely seen, cytoplasm is abundant and eosinophilic. Varying amounts of an extracellular amyloid like material that stains positive with Congo red stain in polarized light is also a typical of these tumours. Concentric calcified masses with a Liesegang’s rings calcification pattern are also pathognomonic for this tumour.

Ai-Ru et.al in 1982 have proposed a sub classification of these features into four main patterns. Although two or more patterns may coexist in the same tumour, a predominance of one type is often seen. Briefly stated those four patterns are,

Pattern 1 - Polyhedral epithelial cell arrangements with deeply eosinophilic cytoplasm and prominent nuclei, cell outlines and intercellular bridges are distinct, frequent cell abnormalities, few or no mitotic figures, and calcifications are present in the fibrous stroma.

Pattern 2- Cribriform appearance of the cell arrangements, intercellular bridges might be discrete; few cell abnormalities, and calcification of the eosinophilic material filling the cribriform spaces with a Liesegang calcification pattern.

Pattern 3- Scattered or dense arrangements of the epithelial cells with varying size and multinucleated giant cells are frequent, mucoid material is present in the stroma.

Pattern 4- Nests and cords of epithelial cells containing either an abundant eosinophilic cytoplasm or a clear vacuolated cytoplasm, variable amounts of stroma containing eosinophilic material, and calcifications.

Histological variants including CEOT with cementum-like components, Clear-cell CEOT (15 cases reported so far), CEOT-containing Langerhans' cells, Combined epithelial odontogenic tumour (CEOT/AOT) and CEOT with myoepithelial cells are discussed in literature.

When clear cells are present with clear cytoplasm, then this variant is referred to as "Clear Cell Variant" or CCEOT. The incidence of the clear cell variant is rare: according to article published in 1994 by Hicks MJ and his colleagues, there were only 9 known cases reported in the literature. However, this indicates that approximately 8% of CEOTs contain clear cells.

Local recurrence rates of 10-15% have been reported and malignant transformation is rare. Clear cell variant of CEOT is reported to be more aggressive and with a higher recurrence rate.

The treatment for CEOT has ranged from simple enucleation or curettage to radical and extensive resection such as hemimandibulectomy or hemimaxillectomy. The choice should be individualized for each lesion because the radiological and histological features may differ from one lesion to another. Since the case reported was of great extension and rapid evolution, the treatment was right mandible segmental resection and titanium plate reconstruction. It could be possible to correlate some characteristics of the gross examination of the surgical resection, like cystic cavity filled with blood, calcified particles, lingual cortex fenestration, multilocular spaces and vascularity, to those found in CT images. The prognosis of the CEOT is good with infrequent recurrence. Malignant behavior is extremely rare. Although it has not been established in the literature, five years should be the absolute minimum follow-up necessary to assess the healing for this type of odontogenic tumor.

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