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.     

Pigmented lateral periodontal cyst and other pigmented odontogenic lesions

OBJECTIVE: To report a case of lateral periodontal cyst (LPC) with marked melanin pigmentation in a 38-year-old Black male and to discuss the phenomenon of melanin pigmentation in odontogenic cysts and tumors.
RESULTS: Histologically, the epithelial lining of the LPC contained an abundant amount of melanin granules throughout the entire epithelium. Ultrastructurally, epithelial cells contained mature melanosomes (stage IV melanosomes). Melanophages containing aggregates of melanosomes were identified in the connective tissue cyst wall. Perusal of the literature revealed that melanin pigmentation in odontogenic lesions is uncommon. Melanin has been reported in calcifying odontogenic cyst (18 cases), odontogenic keratocyst (8 cases), adenomatoid odontogenic tumor (3 cases), ameloblastic fibroma (3 cases), odontoma (2 cases), and amelobastic fibro-odon-toma, odonto-ameloblastoma, and odontogenic fibroma (I case each).
CONCLUSIONS: Almost all pigmented odontogenic lesions occurred in Blacks and Asians; they are almost non-existent in Whites. Thus, racial pigmentation probably plays an important role in such lesions.     

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.     

Glandular odontogenic cyst: analysis of cytokeratin expression and clinicopathological features

The glandular odontogenic cyst (GOC) is a rare odontogenic cyst which is still controversial in regard to classification, terminology, and origin. The first Japanese case of GOC is reported. Immunohistochemical examination for expression of cytokeratins and epithelial membrane antigen by monoclonal antibodies suggested that the lining epithelium was of odontogenic origin with metaplastic mucus-laden cells. We have reviewed the literature and compared the clinicopathological findings of the reported case of GOC with those of botryoid odontogenic cysts (BOC). The anatomical location, age range, and sex of GOC cases were very similar to those of BOC. GOC appears to be a multilocular and mucoe-pidermoid variant of non-keratinizing odontogenic cysts, which also includes BOC. GOC should be separated from the other types of odontogenic cyst and central mucoepidermoid tumours of salivary gland origin.     

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.     

Immunohistochemical and histologic study of cervical lymphoepithelial cysts

Four cases of lateral cervical cysts were reported. All cyst walls were lined with keratinized stratified squamous epithelium, and contained lymph follicles with well-defined germinal centers. Ectopic salivary gland tissue was found in one case. Histochemical examination by the immunoperoxidase method revealed the existence of carcinoembryonic antigen (CEA). However, alpha-feto protein (AFP) and amylase were not detected in any of the cysts. The cyst fluid contained high levels of CEA and high titers of salivary type amylase, but AFP was negative. These results do not support any one of the theories concerning the etiology of cervical lymphoepithelial cysts. It seems likely that cysts derive from both epithelial remnants of the branchial apparatus and from salivary gland inclusions in lymph nodes.     

Case report of a pigmented dentigerous cyst and a review of the literature on pigmented odontogenic cysts

This paper reports the first case of a dentigerous cyst containing melanin-pigment and melanocytes in the lining epithelium, and the first case of a odontogenic cyst with macroscopically visible pigmentation in the cyst wall. The patient was a 29-year-old Japanese male with a cystic lesion in the left retromolar area of the mandible. Pathologic examination revealed the lesion to be a dentigerous cyst with or without mild surface keratinization, and numerous granules of melanin-pigment were distributed in the basal cells of the epithelial lining. Furthermore, dendritic melanocytes were scattered in the basal layer. Review of the literature revealed that pigmented odontogenic cysts are uncommon, and only 11 cases have been documented; eight were odontogenic keratocyst, one was a gingival cyst, one was a botryoid odontogenic cyst, and one was a lateral periodontal cyst. The possible origin of melanocytes in odontogenic lesions is discussed.     

Odontogenic cyst induction by periapical infection in rats

The purpose of this study was to test the hypothesis that Odontogenic cysts can be induced by periapical infection. Pulp extirpation and reaming beyond the root apices were performed in 53 lower first molars in 27 Sprague-Dawley rats. The cavities were left open to allow continuous contamination by oral bacteria. Animals were killed at 6 and more than 8 months after operation. Odontogenic cysts were found in association with 8/53 teeth in 6 animals. Historically, cysts were observed around the lower incisors below the first molars. The cyst wall consisted of fibrous connective tissue with inflammation and was lined with keratinized squamous epithelium. The cyst cavity contained a mass of keratin and necrotic debris. These results support the hypothesis that inflammatory stimulation from the apices can cause cystic changes in the enamel epithelium of underlying teeth.     

Zytokeratinexpression der botryoiden odontogenen Zyste

The botryoid odontogenic cyst (BOC) is considered a rare multilocular variant of the lateral periodontal cyst. The origin of the BOC can be seen in aberrant odontogenic tissue. The BOC is found especially in the premolar region of the mandible, as well as in the frontal region of the maxilla of patients aged between 60 and 70 years. Most of the 11 published articles of BOC have shown high rates of recurrence. Histopathologically the BOC is marked by multilocular cysts lined by a thin, nonkeratinized epithelium. Clusters of glycogen-rich epithelial cells may be noted in nodular thickenings of the cyst lining. For the clinician, the differentiation of the BOC from the keratocyst and ameloblastoma is ¶relevant. One case of a large BOC (65-year-old male, BOC regio 33–45, diameter 5 cm, radiographically and histologically multilocular) is presented with a review of the literature, including the therapeutic management, and the possible diagnostic criteria are discussed. The immunohistochemically determined expression of cytokeratin (CK) 13 implicates the histogenetic origin of the BOC from the squamous epithelium of the oral cavity and excludes the origin from the small salivary glands. The expression of CK 19 and the lack of expression of p53, as well as the higher proliferation rate of the basal epithelial cell layer by the BOC, may be useful for distinction between the keratocyst.     

牙源性囊肿上皮增殖活性的研究

目的：研究牙源性角化囊肿,含牙囊肿,根尖囊肿3种主要的牙源性囊肿衬里上皮的细胞增殖活性,方法：应用Ki-67单克隆抗体免疫组化LSAB法对30例牙源性囊肿进行免疫组化染色,结果通过计算机图像分析,计算单位面积衬里上皮内（mm2)阳性细胞数,进行统计学分析,结果：牙源性角化囊肿衬里上皮有较多的Ki-67阳性细胞,明显高于含牙囊肿和根尖囊肿;正常口腔粘膜未见Ki-67阳性表达,结论：Ki-67在不同的牙源性囊肿中表达的差异显示了它们具有不同的增殖和分化过程。     

Inflammatory paradental cysts in the globulomaxillary region

Cysts located in the maxilla between the roots of an erupted lateral incisor and a canine were studied. Radicular cysts were excluded by the prerequisite of a positive pulp vitality test in both adjacent teeth, and odontogenic keratocysts were excluded by histologic examination. In the period from 1971-1987, 8 cysts were found which fulfilled the criteria for inclusion. The average age of the patients was 18.8 yr. All cysts were lined by a hyperplastic non-keratinized stratified squamous epithelium and there was always a heavy infiltrate of inflammatory cells in the connective tissue. The clinical and histologic features were similar to those previously reported for inflammatory paradental cysts (IPC) in the mandible. Therefore, it seems justified to suggest that some of the previously described globulomaxillary cysts are in fact IPCs.     

The Management of Aggressive Cysts of the Jaws

There are essentially six types of aggressive cysts of the jaws that require special attention, so as to avoid recurrence, or even worse, widespread disease. They include, botryoid cysts, cysts in which carcinoma’s arise, glandular odontogenic cysts, calcifying cystic odontogenic tumour, previously called calcifying odontogenic cyst and unicystic ameloblastoma and keratocystic odontogenic tumor, previously called odontogenic keratocysts. The estimated incidence of these cysts, based on some review studies has been discussed. The main issue, however, when treating a cyst of the jaws is; how sure can one be that the lesion is benign or potentially aggressive? In order to answer this question it is important to know how these cysts commonly present. The clinical presentation, frequency of occurrence and suggested modes of treatment has been addressed.     

The inflammatory paradental cyst: a critical review of 342 cases from a literature survey, including 17 new cases from the author''s files

BACKGROUND: A total of 325 cases of inflammatory paradental cysts (IPCs) and 17 own cases were reviewed. Although known since 1930, the IPC is still unrecognized by many clinicians. The IPCs show a relative frequency of 0.9-4.7%. The majority of cysts occur distally or distobuccally to vital, permanent mandibular molars with a history of pericoronitis (IPC/3rd mandibular molar alone accounts for 64.9%). Radiologically, the cyst appears as a well-defined, semilunar unilocular radiolucency. MATERIALS AND METHODS: Cases of inflammatory paradental cysts and related lesions were retrieved from a worldwide literature survey. In addition, 17 new cases from the files of the authors have been added. RESULTS: The mean ages for patients with IPC/1st, 2nd and 3rd mandibular molars are 8.7, 17.4 and 27.6 years, respectively. The male:female ratio was 1 : 0.9 for IPC/1st and 2nd mandibular molars, and 1 : 0.4 for 3rd mandibular molar. CONCLUSION: Reduced enamel epithelium, cell rests of Malassez and remnants of the dental lamina stimulated by inflammation are thought to play a role in the pathogenesis of IPC. Histological features are indistinguishable from those of the inflammatory, periapical (radicular) cyst.     

Histopathologic study of epithelial components in the connective tissue wall of unilocular type of calcifying odontogenic cyst

Histopathologic study of satellite cysts and odontogenic epithelial islands in connective tissue wall of unilocular type of calcifying odontogenic cyst (COC) was made. The material was 13 cases consisting of 3 simple unicystic COCs, 9 odontome producing COCs and 1 ameloblastomatous proliferating COC. Satellite cysts were found in 6 cases, and were histologically classified into following types: simple cystic, odontome producing and ameloblastomatous. Histologic types of satellite cysts did not coincide with those of main cystic lesions in some cases. Odontogenic epithelial islands with or without proliferating feature were found in 9 cases, and were found in all cases with satellite cysts. Melanin and melanocytes were seen in an ameloblastomatous satellite cysts of 1 of 3 pigmented COCs.     

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.     

Initiation of ectopic epithelial calcification in a calcifying odontogenic cyst

Ultrastructural observation was performed on a calcifying odontogenic cyst (COC) associated with an odontoma and arising in the right mandibular region of an 8-year-old Japanese boy. Four types of cells were identified in the epithelial layer of the COC. The basal cells were low columnar in shape and contained some intracellular organelles. They were attached to the neighboring cells with a few desmosomes and resembled inner enamel epithelium of the normal enamel organ. The stellate reticulum-like cells, polygonal in shape, possessed desmosomes and many cytoplasmic projections. Some intracellular organelles and a few bundles of tonofilaments were observed in the cytoplasm. The light oval cells that were pale staining with toluidine blue contained dilated membranous organelles and many relatively evenly distributed tonofilaments. These cells were usually scattered in the vicinity of the focal accumulations of ghost cells, and the cell membrane was discontinuous in parts. The ghost cells contained many bundles of tonofilaments that were 60-240 nm in diameter and arranged in various directions. No intact intracellular organelles were noted in the cytoplasm. They were attached to the neighboring ghost cells with some desmosomes and their cell membrane was discontinuous in parts. A variety of vesicles, 90-450 nm in diameter, were scattered among the tonofilament bundles. Some of these contained needle-like crystals that were considered to be initial calcification sites in ghost cells. These vesicles presented morphological similarities to matrix vesicles, and it is therefore suggested that matrix vesicle-like structures are deeply involved with initiation of calcification of ghost cells in COC.     

Clinico-pathologic studies on post-operative maxillary cysts

Microscopic and clinical observations on 70 post-operative maxillary cysts were performed. Cysts of 47 cases were lined with the ciliatal epithelium, and 12 cases were composed of both squamous and ciliated cells. Squamous only and cuboidal lining were found in 9 and 2 cases, respectively. Duration after the antrum operation and the non-vital tooth related to the cyst did not affect the epithelial type, though many of the cases of squamous epithelium possessed infectious histories. From the results, the squamous change seemed to be accelerated by inflammatory irritations, and mucous cells in the lining epithelium were depleted as a part of the metaplastic sequence.     

Immunohistochemical and genetic analysis of mandibular cysts in heterozygous ptc knockout mice

BACKGROUND: Alterations of human patched (ptc) homolog have been proven to be responsible for basal cell nevus syndrome (BCNS). Mandibular cysts in heterozygous ptc knockout mouse (ptc+/- mouse) were microradiologically, histologically, immunohistochemically, and genetically examined to investigate the possible role of the ptc gene and its associates in the jaw cysts. METHODS: The mandibular bones were prepared from 63 ptc+/- mice and 6 ptc+/+ mice. Soft X-ray radiographs and histological sections were examined for detection of the presence of mandibular cysts. The mandibular cysts were immunohistochemically investigated using anti-ptc, shh, and smo antibodies. PCR analysis of loss of heterozygosity (LOH) of ptc was performed in genomic DNA from the mandibular cysts. RESULTS: Six ptc+/+ mice showed no pathologic change in any examinations. Microradiologically, ptc+/- mice did not show any apparent lesion. Mandibular cysts were often multiple, and were histologically detected in the alveolar bones or periodontal ligaments of the molars in 16 (25.4%) ptc+/- mice. The mandibular cysts were lined by thin parakeratotic stratified squamous epithelium and contained keratinized materials. Immunohistochemical examination showed sonic hedgehog (shh) protein mainly in cyst lining epithelium, and ptc and smoothened (smo) proteins in cyst lining epithelium, and surrounding fibrous connective tissue. Expression of ptc protein in the cyst lining epithelium tended to be weak as compared with incisor enamel organs and gingival stratified squamous epithelium. LOH of the ptc gene couldn't be found in lining epithelium of mandibular cysts in any ptc+/- mice. CONCLUSIONS: Ptc+/- mouse is a useful model of BCNS from the standpoint of occurrence of jaw cysts, and downregulation of ptc protein in cyst lining epithelium caused by gene targeting would be associated with formation of jaw cysts in ptc+/- mice.     

Ameloblastomatous calcifying odontogenic cyst: a rare histologic variant

Calcifying odontogenic cyst (COC) is an uncommon developmental odontogenic cyst first described by Gorlin in 1962. It is considered as extremely rare and accounts for only 1% of jaw cysts reported. Because of its diverse histopathology, there has always been confusion about its nature as a cyst, neoplasm or hamartoma. Several subclassifications have been proposed. Here, we present a case of calcifying odontogenic cyst with ameloblastic proliferation - an extremely rare histologic variant. The classical histologic features of the lining epithelium in the form of cords and presence of characteristic ghost cells were seen along with ameloblastomatous proliferations. Ameloblastomatous COC microscopically resembles unicystic ameloblastoma except for the ghost cells and calcifications within the proliferative epithelium. The nature of the COC is controversial. The case is presented here for its rarity, and difference between ameloblastomatous COC and ameloblastoma ex COC has been emphasized.