Ghost cells in pilomatrixoma, craniopharyngioma, and calcifying cystic odontogenic tumor: histological, immunohistochemical, and ultrastructural study.

BACKGROUND: Pilomatrixoma, craniopharyngioma, and calcifying cystic odontogenic tumor are the main entities presenting ghost cells as an important histological feature, in spite their quite different clinical presentation; it seems that they share a common pathway in the formation of these cells. The aim of this study is to examine and compare the characteristics of ghost and other cells that form these lesions. METHODS: Forty-three cases including 21 pilomatrixomas, 14 craniopharyngiomas, and eight calcifying cystic odontogenic tumors were evaluated by immunohistochemistry for cytokeratins, CD138, ß-catenin, D2-40, Glut-1, FAS, CD10 and also by scanning electron microscopy. RESULTS: The CKs, CD138, ß-catenin, Glut-1, FAS, and CD10 were more often expressed by transitional cells of craniopharyngioma and calcifying cystic odontogenic tumor, compared with pilomatrixoma. Basaloid cells of pilomatrixoma showed strong positivity for CD138 and CD10. Differences on expression pattern were identified in transitional and basal cells, as ghost cells were negative for most antibodies used, except by low expression for cytokeratins. By scanning electron microscopy, the morphology of ghost cells were similar in their fibrillar cytoplasm, but their pattern varied from sheets in pilomatrixoma to small clusters in craniopharyngioma and calcifying cystic odontogenic tumor. CONCLUSIONS: Mechanisms involved in formation of ghost cells are unknown, but probably they follow different pathways as protein expression in the basal/transitional cells was not uniform in the three tumors studied.

Clinico-radiographic examination of odontogenic myxoma with displacement of unerupted upper third molar: review of the literature / Examen clínico-radiográfico de un mixoma odontogénico con desplazamiento de un tercer molar no erupcionado: revisión de la literatura

Odotogenic myxoma is a benign tumor which presents in 3 percent to 6 percent of all odontogenic tumors. According to the WHO classification, multiple radiolucent areas of varying size, separated by straight or curved bony septa with poorly defined borders are the radiologic characteristics of the condition. We report the case of maxillary odontogenic myxoma in a 21 year old man. The radiological feature of the current case was interesting, due to the size of the lesion and severe displacement of the upper third molar.

El mixoma odontogénico es un tumor benigno que se presenta en el 3 por ciento a 6 por ciento de todos los tumores odontogénicos. De acuerdo a la clasificación de la OMS, las características radiológicas de esta patología presentan múltiples áreas radiolúcidas de tamaño variable, separadas por tabiques óseos rectos o curvos, con márgenes mal definidos. Presentamos un caso de mixoma odontogénico maxilar en un hombre de 21 años. La característica radiológica es interesante, debido al tamaño de la lesión y al desplazamiento severo del tercer molar superior.

Adenomatoid odontogenic tumour of the mandible.

Adenomatoid odontogenic tumour (AOT) is a benign tumour of odontogenic origin. The differential diagnosis of AOT is crucial in terms of surgical management. The 23-year old male patient presented in this case study was referred to the maxillofacial surgery clinic due to the incidental radiological finding of a large osteolytic lesion of the anterior mandible with a retained permanent canine at the base of the bone. Ultrasound imaging revealed the anterior surface of the tooth inside the lesion, indicating extreme thinning of the maintained cortical bone and liquid filling of the cystic lesion. Surgery revealed a bone defect with a deformed, incomplete tooth inside a granulation-like soft tissue. The tooth was extracted and the soft tissues were excavated. Healing was uneventful. Radiographic and physical investigations during long-term follow-up demonstrated complete bone remodeling. Some areas of the tumour were alpha-smooth-muscle-actin positive, indicating a myoepithelial differentiation. Differential diagnosis of AOT to other odontogenic tumours, such as ameloblastoma, is crucial for therapy. Exact morphological diagnosis avoids extensive ablative surgery.

Odontogenic myxoma: clinico-pathological, immunohistochemical and ultrastructural findings of a multicentric series.

The aim of this study was to analyze the clinico-pathological and immunohistochemical features of 62 cases of odontogenic myxoma (OM) diagnosed in three Oral Pathology Diagnostic Services in Latin America, as well as to describe the ultrastructural features of three of these cases. OM showed a wide age range (9-71 years), with a mean of 27.97 yr (SD: 11.01) and a male to female ratio of 1:2.2. Mandible was affected in 37 cases (59.6%) and maxilla in 25 (40.4%), with 61.3% located in the posterior region. Thirty-nine cases (62.9%) were multilocular and 23 (37.1%) unilocular. Size ranged from 1 to 13 cm, (mean: 5.2 cm). Thirty-seven multilocular (54.8%) and 6 unilocular lesions (26%) were larger than 4 cm (p<0.05). Epithelial islands were identified in 5 cases (8%) on H&E stained sections, but AE1/AE3 and CK14 disclosed these structures in 15 cases each (24.2%); CK5 was positive in 8 (12.9%); CK7 in 2 (3.2%) and CK19 in only 3 cases (4.8%). All cases were negative for CKs 8 and 18, S-100 protein, NSE and CD68, and showed a low index of expression of Bcl2 and ki-67 proteins (<1%). Mast cell antibodies showed these cells in 45 cases (72.6%). Myofibroblastic differentiation evidenced by myofilaments and fibronexi was found in one case out of the three studied by TEM and 29 cases (46.7%) were positive by immunohistochemistry for alpha actin. In conclusion, only a minority of OM had epithelial islands, and only 3 cases expressed CK 19, indicating an odontogenic epithelium origin. Immunohistochemical and ultrastructural findings suggest that OM is a mesenchymal neoplasm in which several factors may contribute to its pathogenesis, including myofibroblastic differentiation and the participation of mast cell products. However, further investigations are needed to better understand the participation of these elements in this particular neoplasm.

Immunohistochemical localization of large chondroitin sulfate proteoglycan in odontogenic tumor.

The present study investigated the localization of versican in odontogenic tumors by immunohistochemistry, using paraffin-embedded sections obtained from 27 patients with odontogenic tumors (17 ameloblastomas, 1 adenomatoid odontogenic tumor, 4 odontogenic keratocysts, 1 calcifying odontogenic cyst, 2 ameloblastic fibromas, and 2 malignant ameloblastomas). Deparaffinized sections were immersed in a buffered 1 : 1000 solution of an antibody, 5D5 (raised against a large chondroitin sulfate proteoglycan from bovine sclera), which mainly recognizes versican. All samples showed a positive reaction for versican in connective tissues, whereas positive staining of epithelial nests was observed in only some samples. The positive staining in epithelial nests was in areas showing stellate reticulum-like, cuboidal, columnar cells at the periphery, and tear-drop structures. These results indicated that versican might be involved in, at least in part, the morphogenesis of neoplastic epithelium and mesenchymal tissues in odontogenic tumors.

Argyrophilic nucleolar organizer regions (AgNORs) in odontogenic myxoma (OM) and ameloblastic fibroma (AF).

Ten cases of odontogenic myxoma (OM) and six cases of ameloblastic fibroma (AF) were subjected to comparative analysis by the AgNOR technique, in order to determine a possible difference in cell proliferation index between these lesions. The mean AgNOR number of the mesenchymal component of AF was compared with its epithelial component and the difference was not found to be statistically significant. The mean AgNOR index of the AF group was significantly higher than that of the OM group. Moreover, the mesenchymal component of AF demonstrated increased AgNOR numbers compared with that of OM (P<0.05). These results suggest that the epithelial and mesenchymal components of AF may have similar cell proliferative activity. However, the cell proliferative index of this lesion seems to be higher than that of OM.

A novel cell line that retains the morphological characteristics of the cells and matrix of odontogenic myxoma.

Little is known about the histogenesis of the human odontogenic myxoma or the relation between tumour cells and the matrix. In order to attempt to remedy this situation, we established and investigated a cell line derived from a human odontogenic myxoma. To our knowledge this is the first cell line derived from this tumour. The cell line, named Mix 1, preserved features of the tumour cells. Mix 1 cells expressed vimentin, type I collagen, fibronectin, tenascin and hyaluronic acid. Ultrastructural analysis of cells of the tumour and cell line demonstrated similarities, both containing Golgi apparatus, rough endoplasmic reticulum and mitochondria indicative of secretory cells. Ultrastructural analysis showed the matrix to be represented by bundles of collagen fibrils in the tumour, and by irregular filaments in cultures more than 60 days old. The Mix 1 cell line promises to be an excellent model for investigating the biology of the odontogenic myxoma.

Electron microscopy, micro-analysis, and X-ray diffraction characterization of the mineral-like tissue deposited by human cementum tumor-derived cells.

The nature and characteristics of the mineralized-like tissue deposited by cementoblasts are not well-known due to the difficulties in obtaining and culturing cells representing the cementum phenotype. We hypothesized that a putative cementoblastic cell line derived from a human cementoblastoma could serve as a suitable model to study the physical, chemical, and morphological features of the cementum-like tissue deposited in vitro. The cementoblastoma cell line was studied by transmission electron, high resolution, scanning, and atomic force microscopy and compared with human cellular cementum, human osteoblasts, and human alveolar bone. The analyses of the crystals and mineral-like tissue in the cell line were performed by x-ray diffraction microscopy and energy-dispersive x-ray micro-analysis. TEM examination of cementoblastoma cells revealed the presence of electron-dense intracellular vesicles surrounded by a membrane that contained filaments and needle-like structures. The diffraction patterns obtained from the intracellular material and human cellular cementum were similar, with D-spacings of 3.36 and 2.8, consistent with those of hydroxyapatite (3.440 and 2.814). The composition of the mineral-like tissue had a Ca/P ratio of 1.60 for cementoblastoma cells and 1.97 for human cellular cementum. Na (5.29%) and Cl (1.47%) were present in the composition of cementoblastoma cells. Human cellular cementum additionally contained Mg (4.95%). Osteoblastic cells showed a Ca/P ratio of 1.6280. Na represented 4.52% and Cl 1.22% of its composition. Human alveolar bone had a Ca/P ratio value of 2.01. Na (6.63%), Mg (2.10%), and Cl (0.84%) were also present. All samples examined represented biological-type hydroxyapatite. Based on the compositional and morphological features, these findings indicate that cementoblastoma-derived cells express the human cellular cementum phenotype.

Clear cell variant of calcifying epithelial odontogenic tumor (CEOT) in the maxilla: report of a case with immunohistochemical and ultrastructural investigations.

A rare case of clear cell variant of calcifying epithelial odontogenic tumor is presented with immunohistochemical and ultrastructural investigations. A 14-year-old Japanese girl was admitted with a complaint of swelling in the right posterior maxilla. Radiological examination showed a well-circumscribed radiolucent lesion located close to the impacted third molar. After only a partial tumor excision, the tumor recurred 13 years later. It appeared radiologically as an irregular radiodensity, and a subtotal maxillectomy was performed. Histological examination showed sheets and/or strands composed almost entirely of clear vacuolated epithelial cells in a stroma containing intercellular amyloid-like material and calcification. Histochemical and ultrastructural analysis detected cytoplasmic glycogen granules in the clear cells, and positive immunoreactivities for cytokeratins 8, 13 and 19; filaggrin and anti-ameloblastoma antibodies suggested an odontogenic epithelial origin.

[Ameloblastic fibrosarcoma: an immunohistochemical and ultrastructural study of the mesenchymal component].

To study the characteristics of the mesenchymal cells of ameloblastic fibrosarcoma (AFS), three cases of AFS were studied immunohistochemically and ultrastructurally. The results showed that the mesenchymal component of AFS consisted predominantly of fibroblastic cells with a small number of undifferentiated cells, a few histiocytes and occasionally myofibroblastic cells under electron microscope. The fibroblastic cells were Vimentin positive only, and myofibroblastic cells were positive for Vimentin, HHF35 and alpha-SMA. The histiocytes were positive both for kp1 and PG-M1, suggesting that these cells were infiltrating cells from peripheral blood rather than histiocytic differentiation of tumor cells. Compared with ameloblastic fibroma, AFS showed much higher PCNA labeling index, suggesting higher proliferation activity of AFS.

Human cementum tumor cells have different features from human osteoblastic cells in vitro.

Cells obtained from human cementoblastoma and alveolar bone were isolated and cultured. Initial and late stages of mineralization were assessed by using atomic force microscopy, scanning electron microscopy and X-ray microanalysis. In cultures of cementoblastoma-derived cells the initial stages of mineralization showed well-defined spherical-shaped structures, while the osteoblastic cells showed plaque-like deposits. These morphological patterns of mineral deposition could serve as nucleation centers for hydroxyapatite crystals. Late stages of mineralization at 28 and 35 d maintained those morphological differences established in initial cultures. The material deposited by cementoblastoma and osteoblastic cells, analyzed by EDX spectra, revealed similar Ca/P ratios for both cell types. These values were similar to those reported for hydroxyapatite in enamel and bone. Alkaline phosphatase specific activity (AlP), of osteoblastic cells at 3, 7 and 11 d, showed an increase of 27.9, 50.9 and 37.0% (p < 0.001), respectively. However, at 15 and 19 d there was an increase of AlP activity of cementoblastoma cells by 39.4 and 34.5% over osteoblastic cells (p < 0.001). Immunostaining of cementoblastoma and osteoblastic cells using a specific mAb against a cementum-derived attachment protein revealed strong immunostaining of cementoblastoma cells which was localized to the cell membrane and fibril-like structures (96.2 +/- 1.3). A few osteoblastic cells also stained weakly with the anti-CAP mAb (6.4 +/- 0.6). Sections of decalcified paraffin embedded cementoblastoma specimens, when immunostained with anti-CAP mAb, showed strong immunostaining of the cells surrounding the regular and irregularly-shaped calcified masses of the tumor. Putative cementocytes also stained positively. Immunostaining with a polyclonal antibody against osteopontin strongly stained the osteoblastic cells (89.0 +/- 3.6). Cementoblastoma cells showed weaker staining (54.2 +/- 2.4). The results suggest that cementoblastoma cells could be a major source of specific cementum proteins. These cells could provide the opportunity to elucidate the regulation of the cementogenesis process.

Clear cell odontogenic tumour: a case with induction of dentin-like structures?

A case of clear cell odontogenic tumour, which occurred centrally in the mandible of a 56-year-old Japanese woman, is reported with its histochemical, immunohistochemical and ultrastructural findings. Histologically, the tumour nests were composed of large glycogen-rich clear cells and small non-clear polygonal cells and were separated by thin mature fibrous connective tissue septae. Immunohistochemically, both types of tumour cells showed positive expression of various cytokeratins, in particular cytokeratin 19, and of epithelial membrane antigen. Eosinophilic hyaline deposits and possible dentin-like structures were occasionally formed in contact with the epithelial nests and are regarded as indicative of the epithelial-mesenchymal inductive capacity of this tumour. The aggressive nature of the present tumour was assumed through its invasive growth pattern and occasional mitotic figures. Although it was diagnosed as clear cell odontogenic tumour according to the present WHO classification, the patient must be followed carefully because of its probable malignant nature.

Argyrophilic nucleolar organizer regions (AgNORs) in ameloblastomas and adenomatoid odontogenic tumours (AOTs).

Twenty-two cases of ameloblastoma and ten cases of adenomatoid odontogenic tumour (AOT) were analyzed comparatively by the AgNOR technique. Ameloblastomas were distributed into three groups according to their clinical behaviour: primary lesions without recurrences (PLWTR), 5 cases; primary lesions with recurrences (PLWR), 4 cases; and recurrences, 13 cases. The cases were also regrouped according to their histological pattern: follicular (9 cases), plexiform (7 cases), acanthomatous (4 cases) and unicystic (2 cases). Considering histological patterns, there was a significant statistical difference only between follicular and plexiform types. There were no significant differences between the group of ameloblastomas and the group of AOTs or between the three groups of ameloblastomas with different clinical behaviour. Our results strongly suggest that the distinct clinical behaviour of ameloblastomas and AOT is not correlated with their cellular proliferation ratio. Thus, the infiltrative ability of the ameloblastomas is probably not related to the cellular proliferation index of these tumours.

Odontogenic ghost cell carcinoma: a case report with immunohistochemical and ultrastructural characterization.

The odontogenic ghost cell tumor (OGCT) is the rare, neoplastic variant of the calcifying odontogenic cyst (COC). To date, there have been only four reports of malignant OGCTs, in five patients. We report an additional case of a malignant odontogenic ghost cell tumor that involved the right maxilla of a 20-year-old man. Our report includes its immunocytochemical and ultrastructural characterization.

The adenomatoid odontogenic tumour: ultrastructure of tumour cells and non-calcified amorphous masses.

The ultrastructure of tumour cells and tumour droplets (TD, non-calcified amorphous masses) was studied in three cases of AOT using freshly prepared tissue. The fine structure of the epithelial tumour cells (cell type I-III) corresponded to that of earlier descriptions. The extracellular location of TD was clearly demonstrated. TD were of varying, sometimes bizarre, configuration. Some TD showed a homogeneous matrix; however, in addition most revealed electron-dense plaques. At high magnification, homogeneous types of TD showed only tubular elements; all others revealed granulo-tubular structures. The tubular elements were arranged concentrically. The nature of the TD is discussed and compared to former interpretations. From the present ultrastructural findings, it appears that the TD most probably represent some form of enamel matrix and as such may be considered a type of pre-enamel. Further studies are needed to elucidate the complex structure of the TD-material so characteristic of the AOT.

Odontogenic myxoma of the jaws: a clinical, radiologic, immunohistochemical, and ultrastructural study.

Ten cases of odontogenic myxoma were evaluated radiologically, histologically, and histochemically. Ultrastructural examination was performed in five cases. Stellate cells with branching processes were seen in an abundant acid mucopolysaccharide background. Occasionally macrophages were found in the tumors. In two cases islands of inactive odontogenic epithelium were identified. The ultrastructural features suggest that many lesional cells are very similar to a myofibroblast. With the avidin-biotin complex immunohistochemical technique, the lesions were tested with antibodies to S- 100 protein, neuron-specific enolase, neurofilaments, glial fibrillary acid protein, keratin, desmin, muscle-specific actin, and vimentin. All the lesions were found to be positive for vimentin and muscle-specific actin, and negative for the rest. The results of our study seem to confirm the muscle-specific actin-positivity of odontogenic myxomas as previously reported.

Don't confuse dental soft tissues with odontogenic tumors.

Surgical pathologists are cautioned against the misinterpretation of immature dental tissues (dental papillae and follicles) and dental pulp as odontogenic tumors, especially odontogenic myxomas and fibromas. The close histologic similarity of the immature tissues to tumors may require a clinical-radiologic correlation with the histopathologic specimen in order to distinguish the locally aggressive tumors from innocuous dental tissues.