Carcinoma arising from reduced enamel epithelium

Intra-osseous squamous cell carcinomas are considered to be derived from odontogenic epithelium. Except for an associated benign odontogenic tumor or a cyst, evidence for an odontogenic origin is only circumstantial. In a 73-year-old male, an intra-osseous squamous cell carcinoma in the mandible could be shown to have originated from reduced enamel epithelium. There were no histological features substantiating the odontogenic origin, other than the continuity of tumor epithelium with reduced enamel epithelium surrounding the crown of an impacted molar tooth. Thus, it is concluded that the odontogenic derivation of an intra-osseous squamous cell carcinoma in the jaw cannot be inferred from specific histological features, but should be based on the exclusion of an oral cavity lining epithelial origin. Still more proof is the demonstration of continuity of the carcinoma with odontogenic epithelium, be it normal, cyst lining or benign odontogenic tumor.     

Neoplastic potential of odontogenic cysts

Odontogenic cysts and tumors are distinct entities and quite a common occurrence in the jaw bones. The lining of odontogenic cysts shows a potential for neoplastic transformation to non odontogenic malignancies like squamous cell carcinoma and mucoepidermoid carcinoma, and odontogenic tumors like ameloblastoma and adenoamatoid odontogenic tumor (AOT). AOT is a benign, epithelial odontogenic tumor, common site being the anterior maxilla. Its origin from a dentigerous cyst and in the mandible is rare. A case of an AOT arising from a dentigerous cyst associated with an impacted permanent mandibular left lateral incisor is reported.     

A histological study of odontogenic cysts formed following mouse molar tooth transplantation

Abstract. The enamel organs of subcutaneously transplanted mouse molar teeth undergo cyst formation and present a model for the study of the pathogenesis of developmental odontogenic cysts. Maxillary molars extracted from 10-day-old C57B1 mice were grafted subcutaneously into adult mice of the same strain. The grafts were recovered between 2 and 50 days after operation and routinely prepared for histological examination. After initial degeneration, the enamel organ took the form of a squamous epithelium in which after 5 to 6 days squamous hyperplasia took place. Cystic degeneration within the epithelium produced cavities lined with a thick parakeratotic stratified squamous epithelium which resembled the lining of an epidermoid implantation cyst. As the cysts enlarged the lining changed in appearance to a thin squamous non-keratinized epithelium. Similar features have been described in other experimentally produced cysts and in some odontogenic cysts in humans. Their different morphology may arise from interaction between the surrounding connective tissue with epithelium at different stages of development.     

Intra-osseous squamous cell carcinoma of the maxilla: probably arisen from non-odontogenic epithelium.

This paper reports a case of intra-osseous squamous cell carcinoma (IOSC) of the maxilla. The patient was a 52-year-old male with a chief complaint of swelling of his hard palate. The lesion was initially diagnosed as an incisive canal cyst from the clinical and radiographic findings, but histological examination revealed the lesion to be a poorly differentiated squamous cell carcinoma. The review of the literature yielded only a few previous cases of IOSC of the maxilla, which were probably of odontogenic origin. The present maxillary IOSC is thought to be non-odontogenic in origin.     

Calcifying odontogenic cyst with complex odontoma

A calcifying odontogenic cyst associated with a complex odontoma is described. The presence of reduced enamel epithelium showing extensive proliferation accompanied by dentinoid and enameloid formation, and the morphologic connection of the lining epithelium of the cyst with the enamel epithelium, indicate that the possible origin of the cyst is the enamel epithelium of the odontoma.     

Primary intraosseous carcinoma of the mandible with probable origin in an odontogenic cyst

Primary intraosseous carcinoma of the jaws (PIOC) is an uncommon lesion, but may not be as rare as commonly believed. Since the putative source of the epithelium giving rise to an intraosseous carcinoma is the epithelium involved in odontogenesis, these lesions are often designated as odontogenic carcinomas. These tumors may theoretically arise (1) from the lining of odontogenic cysts, (2) from other epithelial odontogenic tumors, or (3) de novo from presumed odontogenic rests. While not included in most classifications of PIOC, it appears logical to also include intraosseous mucoepidermoid carcinomas as a fourth type of PIOC. A case of primary intraosseous squamous cell carcinoma of the mandible, with evidence of origin in an odontogenic cyst, is presented. The recent literature on carcinomas arising in jaw cysts is reviewed.     

Gingival cyst in adults

A retrospective study is reported of 14 cases of gingival cyst of adults. Clinical data were pooled with well-documented cases in the literature. Most cases occurred in the 5th and 6th decades and in the premolar-canine-incisor area. Microscopically, the epithelial lining ranged from a thin, flat to cuboidal layer, 1-3 cells thick, resembling reduced enamel epithelium, to a nonkeratinized stratified squamous epithelium without rete ridges, of about 5-6 layers. Epithelial cells were frequently atrophic and this could involve the full thickness of the epithelium leaving an amorphous band of eosinophilic material. Plaque-like epithelial thickenings are sometimes present. Multicystic or "botryoid" forms may occur. The cysts are of developmental origin, arising either from basal cell extensions of overlying epithelium; or from postfunctional odontogenic epithelial residues of the dental lamina or rests of Malassez; or from junctional epithelium in the gingival crevice. The latter theory of origin is favored.     

An unusual clinicoradiographic presentation of a lateral periodontal cyst--report of two cases

The lateral periodontal cyst and the botryoid odontogenic cyst are two rare nosological entities, who, despite their radiological and clinical presentation can only be diagnosed by their rather typical histopathological characteristics. The purpose of this article is to report two cases of radiolucent cystic lesions of the mandible, located in the premolar area, with a clinical and radiographic diagnosis of residual cyst, which showed histological features of a lateral periodontal cyst. Histopathologically, the lateral periodontal cyst lining is characterized by a thin cuboidal to stratified squamous non-keratinizing epithelium, ranging from one to five cell layers and presence of one or more epithelial thickenings or plaques. Furthermore, glycogen-rich clear cells encountered either in the epithelial plaques or in the superficial layer of the lining epithelium.     

Adenomatoid Odontogenic Tumor (AOT) Arising from a Dentigerous Cyst: Literature Review and Report of a Case

Adenomatoid odontogenic tumor (AOT) is an uncommon benign tumor of odontogenic origin composed of odontogenic epithelium in a variety of histopathological patterns. These lesions are usually solid but are occasionally cystic. AOT has been reported to occur in association with odontogenic cysts. Very few cases have been described that arise in association with a dentigerous cyst. A systematic search of the English-language medical literature in PubMed and Medline search (keywords adenomatoid odontogenic tumor, dentigerous cyst) data bases revealed only ten such cases.The present case is very unique, exceptional and first of this kind that occurred in the posterior mandible associated with an impacted lower first premolar in a 19-year old female patient. The intraosseous follicular AOT, as this case reported here, frequently resemble dentigerous cysts. There is an uncertainty whether the lining of an associated cyst represents a true dentigerous cyst, cystic change within an AOT or may represent a distinct entity. We believe that this case represents an odontogenic cyst with neoplastic change. Hence, in such cases, the final diagnosis should be made on the basis of histological examination of extensive tissue sampling of entire excised tissue specimen. Further studies to determine whether the AOT derived from an odontogenic cyst could represent a distinct variant are to be done.     

The paradental cyst: a clinicopathologic study of 50 cases

The paradental cyst is an odontogenic cyst of inflammatory origin, which occurs on either the buccal, distal, or (rarely) mesial aspects of partially erupted mandibular third molars. In most cases there is an associated history of recurrent pericoronitis. The clinicopathologic features of 50 cases are reviewed. The frequency of the paradental cyst is 3% to 5% of all odontogenic cysts, although we believe its true incidence to be higher. All cases occur in the mandible, and there is a marked preponderance in males. White persons are affected more frequently than blacks. The size of the cysts varies from 1 to 2 cm; they are attached to the cementoenamel junction (CEJ) and the coronal third of the roots. Histologically, they cannot be distinguished from other inflammatory odontogenic cysts. While origin from junctional epithelium or cell rests of Malassez cannot be entirely excluded, we favor an origin from reduced enamel epithelium and suggest that cyst formation occurs as a result of unilateral expansion of the dental follicle secondary to inflammatory destruction of bone and periodontium.     

Conservative management of unicystic ameloblastoma in a young child: Report of two cases

Unicystic ameloblastoma is a rare, benign, locally invasive odontogenic neoplasm of young age that show clinical, radiographic, or gross features of an odontogenic cyst, but histologically shows typical ameloblastomatous epithelium lining part of the cyst cavity, with or without luminal and/or mural tumor growth. The article presents atypical cases of a large, asymptomatic unicystic ameloblastoma of posterior maxilla and mandibular molar-ramus regions which were treated by surgical enucleation and application of Carnoy's solution for 3 min. The article also describes the importance and complexity of differential diagnosis of an odontogenic lesion sharing common clinical and radiographical features.     

Entstehung eines Plattenepithelkarzinoms auf dem Boden einer odontogenen Zyste

Malignant change in the epithelium of an odontogenic cyst and growth of an invasive squamous cell carcinoma is rare. The diagnosis of malignant disease is mostly only established by histological evaluation of excised tissue because the initial clinical appearance does not differ much from that of odontogenic cysts. The clinical course of one patient after removal of an impacted canine and adjacent cystic tissue is presented. Histological evaluation of the specimen led to diagnosis of a squamous cell carcinoma arising from the cystic epithelium. Partial resection of the maxilla was performed subsequently and 1 year postoperatively the patient was free from recurrence or metastasis. This case report underlines the importance of submitting any soft tissue excised in the treatment of odontogenic cysts to histologic evaluation.     

腺牙源性囊肿两例报告及其细胞角蛋白18的表达

目的探讨腺牙源性囊肿衬里上皮的组织学特征及其细胞角蛋白18、19、CK18-mRNA的表达和该囊肿的组织来源。方法对2例腺牙源性囊肿采用常规HE切片、免疫组织化学染色和原位杂交的方法分别进行组织学观察，检测CK18、CK19和CK18-mRNA的表达。结果囊壁内有微小子囊存在，子囊周围有黏液细胞为主的混合性腺体结构。CK18在囊肿衬里上皮呈阳性表达；在子囊的衬里上皮CK18呈阴性，而CK19呈阳性表达；腺体结构中CK18和CK19均呈阳性表达。在原位杂交中CK18-mRNA在所有上皮中均呈不同程度的阳性表达。结论CK18-mRNA及其蛋白的表达差异可能与囊肿上皮细胞的分化有关，腺牙源性囊肿的角蛋白表达谱存在牙源性上皮和腺源性上皮的交叉，可能同时存在牙源性和腺源性分化。     

Primary intraosseous carcinoma arising from an odontogenic cyst: a case report and review of the Japanese cases

A rare case of primary intraosseous carcinoma (PIOC) arising from an odontogenic cyst in a 58-year-old man is reported. Clinical and radiological examinations revealed an odontogenic cyst of the maxilla. Histopathologically, the lesion was composed of a cyst with a parakeratotic epithelial lining and well-differentiated squamous cell carcinoma, showing continuity between them without a connection to the oral mucosa. Twenty-eight well-documented Japanese cases of Type-1 PIOC, including the present case, were reviewed. The mean age of the 28 patients was 56.1 years, and the male to female ratio was 1.8:1.0. Compared with currently reported Japanese reviews of Type-3, foreign Type-1 and Type-3, there were no significant differences in mean patient age and sexual predominance, and no racial difference. The pathogenesis of Type-1 PIOC is also discussed.     

The mandibular infected buccal cyst (paradental cyst). A radiographic and histological study

Mandibular infected buccal cysts occur on the buccal and distal aspects of the roots of partly or fully erupted mandibular molars with vital pulps. In the present investigation six cases associated with mandibular first and second molars were studied. The cysts were lined with a non-keratinised squamous epithelium with a mixed inflammatory cell infiltrate in the connective tissue. The clinical and microscopic features were similar to those of previously reported paradental cysts. The inflammation always present in these cysts may have an important role in their pathogenesis. It may induce periodontal pocketing, which may lead to hyperplasia and cyst formation in adjacent odontogenic epithelium, which may be either remnants of the reduced enamel epithelium or cell rests of Malassez.     

Hybrid odontogenic tumor of calcifying odontogenic cyst and ameloblastic fibroma

Odontogenic tumors composed of 2 distinct types of lesions are unusual. We report an odontogenic tumor that was composed of calcifying odontogenic cyst and ameloblastic fibroma that occurred in the right posterior maxilla of a 22-year-old Korean woman. The tumor had a cystic component with an ameloblastic epithelial lining and conglomerates of so-called ghost cells, and there were deposits of dentinoid material adjacent to the cyst. These are features characteristic of calcifying odontogenic cyst. Enamel organ-like epithelial islands were observed within a dental papilla-like stroma of the cyst wall. Additionally, a solid portion of the tumor had characteristic features of ameloblastic fibroma, i.e., a myxoid cellular stroma with numerous elongated islands of ameloblastic epithelium. Ghost cell masses were found in the area of ameloblastic fibroma as well. The distribution of the ghost cells suggests that this is a hybrid lesion rather than a collision tumor.     

Squamous-cell carcinoma arising from an odontogenic cyst--the importance of computed tomography in the diagnosis of malignancy

Primary intraosseous carcinoma of the mandible is rare, and when it occurs often arises within or closely associated with an odontogenic cyst. The purpose of this article is to show the role of computed tomography (CT) in the early detection of carcinomatous changes, because of its specificity in establishing the nature of the lesion. An unusual case of a squamous cell carcinoma that arose in an odontogenic cyst is described. The appearance on the panoramic radiograph was suggestive of a benign cystic lesion in the left side of the mandible, but when a CT scan was performed, the appearance of the lesion was compatible with malignancy. Histopathological analysis confirmed the suspicion of a squamous cell carcinoma, but without CT investigation it would be impossible to demonstrate that carcinomatous change had developed from a cystic lesion.     

Peripheral odontogenic tumor: a clinicopathologic study of 30 cases. General features and hamartomatous lesions

BACKGROUND: Peripheral odontogenic tumors (POT), either neoplastic or hamartomatous, are rare. This study briefly summarizes the general features of POT and selectively reviews the histomorphologic spectrum of under-recognized hamartomatous lesions that we have designated peripheral odontogenic hamartomas (POH) in order to shed more light into the pathogenesis of POT. METHODS: Archival material accessioned at our institutions between 1970 and 2004 was systematically searched to identify examples of POT/POH. RESULTS: Among 39 660 biopsies, we retrieved 25 cases of 'classical' POT and five cases of 'unique' POH. Odontogenic fibroma and ameloblastoma were by far the most common. Of POH, two purely epithelial lesions showed multiple strands of basaloid rests [odontogenic gingival epithelial hamartoma (OGEH)] and a conglomerate of polyhedral epithelium, ghost cells and concentric calcifications (calcifying epithelial odontogenic tumor-like hamartoma), respectively. OGEH and peripheral squamous odontogenic tumor (PSOT) deserve to be a related entity. In two types of mixed POH, ectomesenchymal elements appeared juxtaposed to the squamous lining (gingival cyst-like organoid hamartoma) and ghost cells aggregated in the enamel organ of a microdont (peripheral odontoma). None of POH exhibited continuity with the surface epithelium. CONCLUSION: On the basis of this relatively limited series of cases, POH, to conceptualize a unified histogenetic source, are speculated to arise from the soft-tissue remnants of dental lamina. Gingival rests of Serres seem to retain the ability to pursue epithelial-ectomesenchymal interactions that are necessary leading to odontoma formation.     

Microscopic features of the lateral periodontal cyst

abstract — The lateral periodontal cyst is of developmental odontogenic origin and must be differentiated from the gingival cyst of adults, a primordial cyst in a lateral periodontal position, and a cyst of inflammatory origin. This paper is based on a histologic study of five cases. Four were in the mandibular premolar region and one in the lateral incisor-canine region of the maxilla. The cysts are lined by a thin non-keratinized epithelium which resembles the reduced enamel epithelium. Many of them are characterized by the presence of localized plaque-like thickenings of their epithelial linings, consisting of fusiform or large swollen, edematous cells. These epithelial thickenings appear to result from a localized proliferation of basal cells. The lateral periodontal cyst may arise initially as a dentigerous cyst which develops by expansion of the follicle along the lateral surface of the crown and comes to lie on the lateral aspect of the root if tooth eruption is normal. Alternatively, it may arise from the cell rests of Malassez.