A clinical and electron microscopic study of a calcifying epithelial odontogenic tumour

The clinical features and the histological and ultrastructural appearances of a case of calcifying epithelial odontogenic tumour are described. The ultrastructural features of the cells of this tumour are comparable to cells of the stratum intermedium of the enamel organ. It is suggested that the amyloid-staining material found in this tumour is a cellular secretion rather than a cytoplasmic degeneration.     

Amyloid-producing odontogenic tumour (calcifying epithelial odontogenic tumour) in the mandible of a Bengal tiger (Panthera tigris tigris)

A 13-year-old male tiger (Panthera tigris tigris) had a marked mandibular swelling noticed 12 months earlier and associated with progressive anorexia and weight loss. Radiological and post-mortem examination revealed a mass (13x15 cm) which was firm and poorly defined, with destruction of the adjacent bone tissue. Histologically, the mass was poorly demarcated, with infiltrative growth, and composed of nests, cords and islands of epithelial cells with characteristic basal cell features. Also observed were extensive squamous metaplasia, ghost cells, stellate reticulum, and fibroblastic connective tissue stroma containing inflammatory cells. A prominent feature of this tumour consisted of abundant nodular deposits of congophilic amyloid-like material with partial mineralization (Liesegang rings). Immunohistochemically, the neoplastic cells and the amyloid-like material were positive for pancytokeratin and negative for vimentin. The findings supported the diagnosis of an amyloid-producing odontogenic tumour (APOT), also known as calcifying epithelial odontogenic tumour in man and animals.     

The duality of the cell population in a calcifying epithelial odontogenic tumour (CEOT)

Ultrastructural findings in a case of CEOT are reported. It was found that the tumour cells consisted of two populations. One population was composed of polyhedral epithelial cells of the type described previously by other authors. These cells showed variation in size and abundant cytoplasm. They contained large numbers of electron-dense bundles of tonofilaments and numerous mitochondria. The other population was a cell having the ultrastructural characteristics of myoepithelial cells. These cells were arranged juxtaposed to the tumour epithelial cells and had very elongated profiles. They showed a lamina densa which was continuous with that in relation to the basal plasma membrane of the tumour epithelial cells and also a large number of hemidesmosomes. These cells also contained large numbers of fine filaments with electron-dense bodies similar to those described in smooth muscle cells. The amyloid-like material was found to consist of two types of structures which are probably related. One type showed sheets of low electron-dense filaments, the other aggregates of lamina densa fragments.     

Odontogenic tumor with combined characteristics of adenomatoid odontogenic and calcifying epithelial odontogenic tumors

A very rare odontogenic epithelial tumor with the combined characteristics of an adenomatoid odontogenic tumor (AOT) and calcifying epithelial odontogenic tumor (CEOT) was found in a 27 year old female. The histopathology, immunohistochemistry of keratin, lectin-binding patterns and distribution of carbonic anhydrase were determined. The nature of the calcified bodies was also examined biophysically. The tumor consisted of cuboidal and columnar odontogenic epithelial cells in the cystic wall, and AOT and CEOT in the central cavity. Odontogenic epithelial cells forming the cyst wall in the CEOT were positive for TK- and KL1-keratins, while that detected with PKK1 antibody was absent in the tumorous epithelium. Lectin binding of tumor epithelial cells was examined with Concanavalin A (Con A), peanut agglutinin (PNA), soybean agglutinin (SBA), dolichos biflorus agglutinin (DBA), wheat germ agglutinin (WGA), ricinus communis agglutinin (RCA-I), and ulex europeus agglutinin I (UEA-I) lectins, and the tumor epithelium indicated existence of glucose, mannose, Gal, GalNAc, and GlcNAc residues. The lectin binding patterns of the calcified material showed an increased intensity by enzymatic pretreatments. With an electron probe X-ray microanalyser (EPMA), the calcified lesions gave a high peak for calcium ion and for phosphorus ion and a low one for magnesium ion, as obtained from line and surface analysis.     

The amyloid deposit in calcifying epithelial odontogenic tumor is immunoreactive for cytokeratins

Calcifying epithelial odontogenic tumor, also known as Pindborg tumor, is a rare benign tumor with locally aggressive behavior. It is characterized by squamous epithelial cells, calcifications, and eosinophilic deposits that have been identified as amyloid. We report a case of calcifying epithelial odontogenic tumor and investigate the nature of the amyloid, using histologic, immunohistochemical, and ultrastructural studies. The amyloid was immunohistochemically negative for basement membrane components and positive for all cytokeratin stains performed (cocktail of cytokeratins 1, 5, 6, 8, 13, and 16, and cytokeratins AE1 and AE3). The amyloid stained focally in a glandular-like pattern, reminiscent of the epithelial glandlike structures of the tumor. We conclude that the amyloid is derived from filamentous degeneration of keratin filaments that originate from the tumor squamous epithelium. The keratin degeneration is part of a developmental or aging process that the tumor undergoes.     

Pindborg tumor or odontogenic calcifying epithelial tumor. A clinical case]

Calcifying epithelial odontogenic tumour (CEOT) is an uncommon odontogenic neoplasm first recognized as a distinct entity by Pindborg in 1955. One of the frequent histological findings is the occurrence of amorphous deposits of so called amyloid like material within the tumour. A case of this tumour is reported in a 75 years woman.     

Ghost cell odontogenic carcinoma arising in calcifying odontogenic cyst

A case of exceptionally rare odontogenic malignant tumor, called ghost cell odontogenic carcinoma, is described. The tumor was considered to be derived from calcifying odontogenic cyst, which had been resected 5 years before. In the present resected specimen, cellular atypia, mitotic activity, Ki-67 labeling index, and p53 positivity were all increased in comparison with the initially resected specimen. This is a valuable case in which malignant transformation from calcifying odontogenic cyst to ghost cell odontogenic carcinoma was proven by the histopathologic and immunohistochemical findings. Pathologists should be aware of this rare entity.     

Cytogical features of calcifying epithelial odontogenic tumor (Pindborg tumor) with abundant cementum-like material

Calcifying epithelial odontogenic tumor (CEOT) is a rare tumor, most frequently occurring in the mandible and composed of large sheets of epithelial cells, sometimes showing nuclear pleomorphism. This paper was aimed at reporting of the cytological features of an unusual case of CEOT, affecting a 14-year-old female, with abundant deposition of intercellular calcified material. The cytological preparations were characterized by large clusters of scarcely cohesive, large polyhedral cells and abundant calcified material. The latter consisted of intensely basophilic substance either in large clusters or discrete concretions and, at high-power view, occasional tumor cells also contained calcified material. Histologically, the uncalcified stroma displayed focal Congo Red positivity with the typical birefringence under polarized light. The neoplastic cells were consistently immunoreactive for epithelial membrane antigen, vimentin and, to a lesser extent, for wide spectrum cytokeratins (AE1 AE3) and cytokeratins 8-18 and 19. The cytological features of CEOT are rather characteristic, and the detection of intra- and extracellular calcifications may help to differentiate this neoplasm from others that most commonly arise in this area.     

Pigmented variant of calcifying odontogenic cyst. Report of an additional case and review of the literature

A case of the pigmented variant of calcifying odontogenic cyst occurring in a 21-year-old Japanese male is reported, and a review of previously reported cases of the lesion is included. In addition to the characteristic histopathologic features of calcifying odontogenic cyst, dendritic cells containing melanin pigment were widely distributed in the epithelial layer and melanin pigment was also found in the epithelial cells including ghost cells in the present case. Although no conclusion could be drawn from the present examination as to the origin of melanin pigment in the calcifying odontogenic cyst, it is thought that the role of racial pigmentation is one of the important factors in occurrence of pigmented odontogenic lesions.     

Histoenzymological and ultrastructural study of a bifocal calcifying epithelial odontogenic tumor. characteristics of epithelial cells and histogenesis of amyloid-like material

Summary A calcifying epithelial odontogenic tumor, simultaneously located in the two jaws (maxilla and mandible) was examined by histochemical and electron microscopic methods. Squamous tumor cells without secretory polarity were different from those of common ameloblastoma. High activities of alkaline phosphatase and ATPases were demonstrated by light and electron microscopy on the cytoplasmic membrane, findings similar to those in the stratum intermedium cells of the normal dental germ from which these tumor cells seem to arise. The tumor cells, like preameloblasts of the dental germ, also produce a granulo-filamentous material in intracytoplasmic vesicles and discharge it into the stroma. This pseudo-amyloid substance represents an abnormal protein of the enamel matrix and calcification, mainly occurring in that substance, might be an attempt at mineralization.     

颌骨牙源性钙化囊肿病变性质的探讨

目的：明确所谓牙源性钙化囊肿（calcifying odontogenic cyst,COC)各临床病理亚型的特点及其病变性能。方法：回顾分析21例被笼统诊断为COC病例资料,通过对临床、X线、病理、治疗及预后特点的综合分析,将本组病例分为囊肿、良性肿瘤和恶性肿瘤3类病损进行观察。结果：囊肿组16例（男性9例、女性7例）,10－19岁为高发年龄,前磨牙区好发,随访13例患者无复发。良性肿瘤组4例,临床病理表现各异,其中2例表现为所谓实性型COC,1例为COC伴发成釉细胞瘤,1例为COC伴发牙源性纤维黏液瘤;这组病例均发生于下颌,其中2例有多次复发史。恶性肿瘤组1例,肿瘤呈实性,除表现某些COC特点外,具有显著的组织学恶性特点。结论：以往被笼统归类为COC的病变可表现囊肿,良性肿瘤或恶性肿瘤等多种病理和行为特点,因此其命名和分类应作相应修改,临床治疗也应区别对待。     

Pigmented adenomatoid odontogenic tumour

Summary A pigmented adenomatoid odontogenic tumour occurring in the mandible of a 12-year-old Japanese girl is reported. In addition to the characteristic histopathologic features, fine granules and coarse aggregates of melanin pigment were widely distributed in the spindle-shaped epithelial cells between duct-like structures, and dendritic cells containing melanin pigment were also distributed in tumour epithelium. The possible histogenesis of melanin pigment in the epithelial cells of the odontogenic lesions is discussed, although no firm conclusions could be drawn.     

Benign epithelial odontogenic tumors

Teeth are formed from a complex interaction of primitive ectoderm and ectomesenchymal tissues. Because humans develop 2 sets of teeth (deciduous and permanent), odontogenesis is a prolonged biologic process. Residues of odontogenic tissues are present in most humans- both during and after odontogenesis. These elements may be found in either bone or soft tissue of the jaws and may contribute to the formation of odontogenic tumors in these sites. Further, the mixture of epithelium and mesenchyme necessary for tooth formation allows for the development of tumors composed of either element or for mixed neoplasms. This article discusses 4 of the 5 benign odontogenic neoplasms that are of epithelial origin and offers an agreed on classification scheme, which includes important clinicopathological subtypes. Specifically discussed are ameloblastoma, calcifying epithelial odontogenic tumor (Pindborg tumor), adenomatoid odontogenic tumor, and squamous odontogenic tumor. A brief history of each tumor is given along with a discussion of demographic data, clinical findings, radiographic features, and gross features where useful. A thorough discussion is presented of diagnostic histopathology including histologic variants. Generally accepted modes of therapy and follow-up recommendations are discussed.     

Benign epithelial odontogenic tumors

The group of benign epithelial odontogenic tumors consists of the four member types of the ameloblastoma family (solid/multicystic, extraosseous/peripheral, desmoplastic, unicystic), squamous odontogenic tumors, calcifying odontogenic tumors, adenomatoid odontogenic tumors, and keratocystic odontogenic tumors, the former "keratocysts" that were recently reclassified by the World Health Organization and are now regarded as tumors. The latter are by far the most frequent tumors in this group, followed by solid/multicystic ameloblastoma. Although the etiology of these lesions is still unknown, a close relationship to normal tooth development is obvious, which is partially imitated by some tumors. Despite some similarities to each other, at least in part, the biological behavior of these lesions is quite different, as are treatment modalities. The diagnosis is essentially based on localization (intraosseous vs. extraosseous/peripheral) and histology, whereupon the correlation of histological findings with radiographic morphology may be of additional diagnostic value. Because of the range of variation, immunohistochemical investigations are not helpful in diagnosing a particular case.     

Malignant epithelial odontogenic tumors

Malignant epithelial odontogenic tumors are very rare. They may arise from the epithelial components of the odontogenic apparatus. The rests of Malassez, the reduced enamel epithelium surrounding the crown of an impacted tooth, the rests of Serres in the gingiva, and the linings of odontogenic cysts represent the precursor cells for malignant transformation. Because metastatic carcinoma is the most common malignancy of the jaws, the diagnosis of a primary intraosseous carcinoma must always be made to the exclusion of metastatic disease. Odontogenic carcinomas include malignant (metastasizing) ameloblastoma, ameloblastic carcinoma, primary intraosseous squamous cell carcinoma, clear cell odontogenic carcinoma, and malignant epithelial ghost cell tumor. There are specific histopathologic features that support the diagnosis of a primary carcinoma of odontogenic epithelium which are presented in this article. Immunohistochemical (IHC) staining is important for distinguishing clear cell odontogenic carcinoma from metastatic renal cell tumors, yet IHC stains are not particularly helpful for other lesions in this group-all of which exhibit low molecular weight cytokeratin positivity. Aggressive growth and nodal and distant metastases occur with all of these entities.     

Aggressive osteoblastoma of the mandible closely simulating calcifying epithelial odontogenic tumor. Report of two cases with unusual histopathologic findings

Aggressive osteoblastoma is a rare bone-forming neoplasm composed of prominent epithelioid cells that demonstrate locally invasive growth with a high rate of recurrence but no metastatic potential. Clinical, radiographic and pathologic features of mandibular aggressive osteoblastoma in a 21-year-old African-American male and a 12-year-old Caucasian female are presented. Both tumors were resected with wide surgical margins and neither patient had adjuvant radiation or chemotherapy. The patients showed no evidence of local recurrence or distant spread either clinically or radiographically after two years of follow-up. These tumors were composed of solid sheets of pleomorphic epithelioid cells, eosinophilic amorphous osteoid with foci of calcification, which closely simulated amyloid. Differentiation of this tumor from histologically similar calcifying epithelial odontogenic tumor and low-grade osteosarcoma proved difficult. Immunohistochemical study with osteocalcin confirmed the osteoblastic nature of these epithelioid cells.