Primordial odontogenic tumor: An immunohistochemical profile

BACKGROUND

Primordial Odontogenic Tumor (POT) is a recently described odontogenic tumor characterized by a variably cellular loose fibrous tissue with areas similar to the dental papilla, covered by cuboidal to columnar epithelium that resembles the internal epithelium of the enamel organ, surrounded at least partly by a delicate fibrous capsule. The purpose of this study was to investigate the possible histogenesis and biological behavior of this rare tumor by means of a wide immunohistochemical analysis of its epithelial and mesenchymal components.

MATERIAL AND METHODS

The immunoexpression of twenty-three different antibodies were evaluated in four cases of POT.

RESULTS

The epithelial cells that cover the periphery of the tumor showed immunopositivity for Cytokeratins 14 and 19, while Amelogenin, Glut-1, MOC-31, Caveolin-1. Galectin-3, PITX2, p53, Bax, Bcl-2, Survivin and PTEN were variably expressed in focal areas. The mesenchymal component of the tumor was positive for Vimentin, Syndecan-1, PITX2, Endoglin (CD105), CD 34, Cyclin D1, Bax, Bcl-2, Survivin and p53. PTEN and CD 90 showed a moderate positivity. BRAF V600E and Calretinin were negative in all samples. Cell proliferation markers (Ki-67, MCM-7) were expressed in <5% of the tumor cells.

CONCLUSIONS

According to these immunohistochemical findings, we may conclude that POT is a benign odontogenic tumor in which there is both epithelial and mesenchymal activity during its histogenesis, as there is expression of certain components in particular zones in both tissues that suggests this tumor develops during the immature (primordial) stage of tooth development, leading to its inclusion within the group of benign mixed epithelial and mesenchymal odontogenic tumours in the current World Health Organization classification of these lesions.

[Primary intra-osseous carcinoma]

Primary intra-osseous carcinoma (PIOC) is a rare tumor, defined as squamous cell carcinoma that develops in the jaw bones, having no initial connection to adjacent skin or mucosa. It is locally aggressive, with metastases to regional lymph nodes, (28% of cases) and lung (5% of cases) at the time of diagnosis. Its origin may be di novo or from other odontogenic tumors. The maxillary bones have epithelial tissues; therefore this neoplasm is located exclusively on this site, predominantly in the jaw. PIOC diagnostic criteria are strict and include: squamous cell carcinoma histopathology, lack of commitment and sinus mucosa, ruling out the possibility of metastasis from a distant site with a thorough clinical study and complementary methods. The treatment is, whenever possible, oncologic resection, additional radio and / or chemotherapy. Reconstructive surgery with graft and / or prostheses for aesthetic and functional are also required. We report the case of a 72 years old man who consulted for sore jaw three months after molar extraction. Curettage biopsy was performed and then resected mandible with lymphadenectomy. Histopathological examination showed a poorly differentiated squamous cell carcinoma, infiltrating jawbone with morphological findings linking him to residual odontogenic cyst and metastatic lymph nodes in 15 of 48 isolates. Postoperative radiotherapy was performed, he died at 30 months of diagnosis by progressive deterioration.

Expression of basement membrane components in odontogenic tumors

OBJECTIVE

The objective was to characterize the expression of BMCs (laminins 1 and 5, collagen type IV, and fibronectin) in ameloblastomas, calcifying cystic odontogenic tumors (CCOTs), and adenomatoid odontogenic tumors (AOTs).

STUDY DESIGN

BMCs were analyzed in 14 ameloblastomas, 7 CCOTs, and 7 AOTs using immunohistochemistry.

RESULTS

In normal oral mucosa, linear deposits of these proteins were found at the epithelial-mesenchymal junction, but not in epithelial cytoplasm. In all tumors studied, linear deposits of all proteins were found at the epithelial-mesenchymal junction; laminin 1 was expressed in all tumor cells, regardless of cell types. For CCOTs, laminin 5 was found faintly in suprabasal cells, but expressed strongly in ghost cells. For AOTs, laminin 5 strongly decorated tumor cells adjacent to mineralization.

CONCLUSIONS

Laminin 1 may be a marker for odontogenic epithelium. Additionally, laminin 5 may be involved in ghost cell formation and initiation of calcification.

Immunohistochemical detection of phosphorylated Akt, PI3K, and PTEN in ameloblastic tumors

OBJECTIVE

To evaluate roles of the Akt signaling pathway in oncogenesis and cytodifferentiation of odontogenic tumors, expression of phosphorylated Akt (pAkt), PI3K, and PTEN was analyzed in ameloblastic tumors as well as in tooth germs.

METHODS

11 tooth germs, 40 ameloblastomas, and 5 malignant ameloblastic tumors were examined immunohistochemically with antibodies against pAkt, PI3K, and PTEN.

RESULTS

Immunoreactivity for pAkt, PI3K, and PTEN was detected predominantly in odontogenic epithelial cells near the basement membrane in tooth germs and ameloblastic tumors. The levels of immunoreactivity for pAkt and PI3K were slightly higher in ameloblastic tumors than in tooth germs. Plexiform ameloblastomas showed significantly higher expression of PI3K than follicular ameloblastomas, and PI3K immunoreactivity in ameloblastomas without cellular variation was significantly higher than that in acanthomatous ameloblastomas. The level of PTEN immunoreactivity was significantly lower in ameloblastomas than in tooth germs.

CONCLUSION

Expression of pAkt, PI3K, and PTEN in tooth germs and ameloblastic tumors suggests that these signaling molecules regulate cell survival and growth in normal and neoplastic odontogenic tissues by mediating growth factor signals. Increased expression of pAkt and PI3K and decreased expression of PTEN in ameloblastic tumors may participate in oncogenesis of odontogenic epithelium by activating the Akt signaling pathway.

Quantitative analysis of argyrophilic nucleolar organizer regions and epidermal growth factor receptor in ameloblastomas

OBJECTIVE

The aim of this study was to evaluate the proliferation activity by means of the quantification of the argyrophilic nucleolar organizer regions (AgNORs) and the patterns of expression of the epidermal growth factor receptor (EGFR) in ameloblastomas.

METHOD

The methods of evaluation included the H/E stain for the morphologic analysis, the silver impregnation technique for quantification of the AgNORs and the immunohistochemical stain with anti-EGFR antibody in 11 cases of ameloblastoma.

RESULTS

The results did not show a significant statistical difference as per quantification of the AgNORs. The expression of the EGFR on the epithelial islands of ameloblastoma was not uniform, and the location of the expression was also variable. The predominant expression was that of cytoplasm and the islands with an expression of membrane only were rare and generally smaller in size.

CONCLUSION

The tumor presents an irregular growth. Smaller islands are associated with a higher proliferation activity and therefore could be responsible for tumor infiltration.

Immunohistochemical detection of insulin-like growth factors, platelet-derived growth factor, and their receptors in ameloblastic tumors

BACKGROUND

To evaluate the roles of growth factors in oncogenesis and cytodifferentiation of odontogenic tumors, expression of insulin-like growth factors (IGFs), platelet-derived growth factor (PDGF), and their receptors was analyzed in ameloblastic tumors as well as in tooth germs.

METHODS

Tissue specimens of 10 tooth germs, 47 ameloblastomas, and five malignant ameloblastic tumors were examined immunohistochemically with the use of antibodies against IGF-I, IGF-II, IGF-I receptor (IGF-IR), PDGF A-chain, PDGF B-chain, PDGF alpha-receptor, and PDGF beta-receptor.

RESULTS

Immunohistochemical reactivity for IGFs, PDGF chains, and their receptors was detected predominantly in odontogenic epithelial cells near the basement membrane in tooth germs and in benign and malignant ameloblastic tumors. The expression levels of IGF-II and PDGF chains were significantly higher in ameloblastic tumors than in tooth germs. Malignant ameloblastic tumors showed higher reactivity for PDGF chains than benign ameloblastomas and higher reactivity for platelet-derived growth factor receptors than tooth germs. The expression levels of PDGF chains were significantly higher in follicular ameloblastomas than in plexiform ameloblastomas. Desmoplastic ameloblastomas showed higher expression of IGFs and IGF-IR when compared with other ameloblastoma subtypes.

CONCLUSION

Expression of IGFs, PDGF, and their receptors in tooth germs and ameloblastic tumors suggests that these growth factor signals contribute to cell proliferation or survival in both normal and neoplastic odontogenic tissues. Expression of these molecules in odontogenic tissues possibly affects interactions with the bone microenvironment during tooth development and intraosseous progression of ameloblastic tumors. Altered expression of the ligands and receptors in ameloblastic tumors may be involved in oncogenesis, malignant potential, and tumor cell differentiation.

Odontogenic Myxoma: A Clinicopathologic Study of 25 Cases

Context.—Odontogenic myxoma is an uncommon tumor that has the potential for extensive destruction of the jaws.

Objective.—To document the clinical, pathologic, and behavioral features of odontogenic myxomas.

Design.—Histologic and immunocytochemical examinations were performed on odontogenic myxomas from 25 Chinese patients. Clinical and available follow-up data were analyzed.

Results.—In the present series, 13 were male and 12 female. The age at diagnosis ranged from 6 to 66 years, with a mean age of 28.8 years. Twelve tumors involved the mandible and 13 occurred in the maxilla, with a predilection for posterior areas. The posterior maxillary tumors frequently (9/10) involved the maxillary sinus. Of the 23 cases with radiographic records, 22 lesions presented with a multilocular appearance. Although 80% of the mandibular lesions showed a well-defined border, only 33.3% of the maxillary tumors were well-defined. Histologically, odontogenic myxomas were mainly composed of spindled or stellate-shaped cells in a mucoid-rich intercellular matrix. Tumors containing noticeable fibrous components were evident in 13 cases. Apart from 5 cases treated conservatively by enucleation, the remaining 20 cases were treated by relatively radical procedures, including block/segmental resection and partial or total maxillectomy or mandibulectomy. Follow-up data were available on 22 patients and only 1 patient initially treated by enucleation had a recurrence.

Conclusions.—Odontogenic myxomas have a very bland histologic appearance that lacks atypia and may easily lead to misdiagnosis. The tumors are infiltrative with no capsulation and may recur after inadequate surgery.

Immunohistochemical detection of platelet-derived endothelial cell growth factor/thymidine phosphorylase and angiopoietins in ameloblastic tumors

BACKGROUND

To evaluate the roles of angiogenic factors in the development and progression of odontogenic tumors, expression of platelet-derived endothelial cell growth factor/thymidine phosphorylase (PD-ECGF/TP) and of angiopoietins in ameloblastic tumors as well as in tooth germs.

METHODS

Tissue specimens of 11 tooth germs, 44 ameloblastomas, and five malignant ameloblastic tumors were examined immunohistochemically with the use of antibodies against PD-ECGF/TP and angiopoietin-1 and -2.

RESULTS

Immunohistochemical reactivity for PD-ECGF/TP was detected in mesenchymal cells in tooth germs and stromal cells in ameloblastic tumors, and the level of immunoreactivity for PD-ECGF/TP was significantly higher in ameloblastomas than in tooth germs. Granular cell ameloblastomas showed PD-ECGF/TP reactivity in granular neoplastic cells as well as in stromal cells. Immunoreactivity for angiopoietin-1 and -2 was detected predominantly in odontogenic epithelial cells near the basement membrane in tooth germs and in benign and malignant ameloblastic tumors. Malignant ameloblastic tumors had decreased angiopoietin-1 reactivity and ameloblastic carcinomas had increased angiopoietin-2 reactivity as compared with the respective levels in tooth germs and ameloblastomas. Immunohistochemical reactivity for angiopoietin-2 was slightly higher in follicular ameloblastomas than in plexiform ameloblastomas.

CONCLUSION

Expression of PD-ECGF/TP and angiopoietin-1 and -2 in tooth germs and ameloblastic tumors suggests that these angiogenic factors participate in tooth development and odontogenic tumor progression by regulating angiogenesis. Altered expression of PD-ECGF/TP and angiopoietins in ameloblastic tumors may be involved in oncogenesis, malignant potential, and tumor cell differentiation.

Immunohistochemical detection of MT1-MMP, RECK, and EMMPRIN in ameloblastic tumors

BACKGROUND

To evaluate the roles of matrix-degrading proteinase regulators in progression of odontogenic tumors, expression of membrane-bound matrix metalloproteinase (MMP) MT1-MMP, MMP inhibitor RECK and MMP inducer EMMPRIN was analyzed in ameloblastic tumors as well as in tooth germs.

METHODS

Tissue specimens of 11 tooth germs, 40 ameloblastomas, and five malignant ameloblastic tumors were examined immunohistochemically with the use of antibodies against MT1-MMP, RECK, and EMMPRIN.

RESULTS

Immunohistochemical reactivity for MT1-MMP, RECK and EMMPRIN was detected predominantly in odontogenic epithelial cells near the basement membrane in tooth germs and benign and malignant ameloblastic tumors. The level of immunoreactivity for MT1-MMP was slightly higher in benign and malignant ameloblastic tumors than in tooth germs. RECK expression was lower in ameloblastomas than in tooth germs. Follicular ameloblastomas showed significantly lower expression of RECK than plexiform ameloblastomas, and immunoreactivity for RECK in acanthomatous ameloblastomas was slightly lower than that in other cellular variants.

CONCLUSION

Expression of MT1-MMP, RECK and EMMPRIN in tooth germs and ameloblastic tumors suggests that these normal and neoplastic epithelial components control MMP-dependent extracellular matrix (ECM) degradation during tooth development and tumor progression via epithelial-mesenchymal interactions.

Differential expression of apoptosis-related proteins in various cellular components of ameloblastomas

To evaluate the expression patterns of apoptosis-related proteins, including Fas, Fas-ligand (FasL), caspase-3 and Bcl-2, in various cellular components of ameloblastomas, 39 cases of ameloblastoma were examined using immunohistochemistry. The staining intensity of the antigens in the 4 types of tumour cellular component, peripheral basal cells of tumour nests, central stellate reticulum-like cells, and foci of squamous and granular cells, was scored using a semi-quantitative scale, and comparisons were made by statistical analysis. Expression of Fas, FasL and caspase-3 was detected in the majority of cases, with a similar pattern of strong staining in the foci of squamous metaplasia and granular cells usually situated in the central area of tumour islands. In contrast, expression of Bcl-2 was predominantly seen in the peripheral basal cell layer. There were significant differences in the staining intensity of Fas, caspase-3 and Bcl-2 among the 4 types of tumour cell. The differential expression of apoptosis-related proteins in various cellular components of ameloblastomas, with pro-apoptotic proteins, Fas, FasL and caspase-3 being closely associated with squamous metaplasia and granular transformation of the tumour cells, suggests that Fas/FasL-induced apoptotic cell death may play a role in the disposal of terminally differentiated or degenerative tumour cells in ameloblastomas.

Desmoplastic fibroma of the jaw: a case report and review of literature

Desmoplastic fibroma is a benign intraosseous neoplasm that is recognized as the intraosseous counterpart of soft tissue fibromatosis in both gnathic and extragnathic sites. It has a propensity for locally aggressive behavior and local recurrence. In the present report, we define the clinicopathological and radiographic features of a desmoplastic fibroma of the mandible in an 8-year-old white boy who initially presented with a 2-month history of a rapidly expanding, painless mass along the right inferior border of his mandible. A critical and comprehensive review of the English language literature is also provided.

Psammomatoid ossifying fibromas: immunohistochemical analysis and differential diagnosis with psammomatous meningiomas of craniofacial bones

OBJECTIVE

To clarify the role of immunohistochemistry in the diagnosis of psammomatoid ossifying fibroma (PSOF), conventional cemento-ossifying fibroma (COF), and psammomatous meningioma (PM) of the craniofacial skeleton.

STUDY DESIGN

The histology and immunohistochemistry of 4 PSOFs, 6 COFs, and 7 PMs was studied. Antibodies included EMA, cytokeratins, smooth muscle actin (SMA), desmin, vimentin, CD34, CD10, S-100 protein, and glial fibrillary acidic protein (GFAP).

RESULTS

All PSOFs showed multiple round ossicles homogeneously distributed within a fibroblastic stroma. Psammomatous meningiomas had meningothelial features. All tumors, except 1 COF, were positive for EMA. All of them expressed vimentin, and none showed cytokeratins. Staining for SMA and S-100 protein was variable. CD10 was positive in all cases except 2 meningiomas. CD34 and GFAP stained only 1 case of meningioma each.

CONCLUSIONS

The diagnosis of PSOF should rest on histologic features. An incorrect diagnosis of meningioma based on the expression of EMA should be avoided.

Immunohistochemical detection of beta-catenin and adenomatous polyposis coli in ameloblastomas

BACKGROUND

To clarify the roles of the Wnt signaling pathway in oncogenesis and cytodifferentiation of odontogenic tumors, expression of beta-catenin and adenomatous polyposis coli (APC) was analyzed in ameloblastomas as well as in tooth germs.

METHODS

Tissue specimens of 10 tooth germs, 40 benign ameloblastomas, and five malignant ameloblastomas were examined immunohistochemically with the use of antibodies against beta-catenin and APC.

RESULTS

Immunohistochemical reactivity for beta-catenin was detected in the cell membrane and cytoplasm of most odontogenic epithelial cells in tooth germs and ameloblastomas. Nuclear beta-catenin expression was recognized in nine of 40 ameloblastomas and two of five malignant ameloblastomas, but not in tooth germs. APC was evidently expressed in odontogenic epithelial cells neighboring the basement membrane in tooth germs and ameloblastomas, and the reactivity was significantly lower in benign and malignant ameloblastomas than in tooth germs. Follicular ameloblastomas and acanthomatous ameloblastomas tended to show high nuclear beta-catenin expression and low APC reactivity, as compared with other ameloblastoma variants.

CONCLUSION

Expression of beta-catenin and APC in tooth germs and ameloblastomas suggests that aberration of the Wnt signaling pathway might play a role in oncogenesis and cytodifferentiation of odontogenic epithelium via deregulation of cell proliferation.

Calcifying epithelial odontogenic (Pindborg) tumor-associated amyloid consists of a novel human protein

Calcifying epithelial odontogenic tumors (CEOTs), also known as Pindborg tumors, are characterized by the presence of squamous-cell proliferation, calcification, and, notably, amyloid deposits. On the basis of immunohistochemical analyses, the amyloidogenic component had heretofore been deemed to consist of cytokeratin-related or other molecules; however, its chemical composition had never been elucidated. We have used our microanalytic techniques to characterize the protein nature of CEOT-associated amyloid isolated from specimens obtained from 3 patients. As evidenced by the results of amino-acid sequencing and mass spectrometry, the fibrils were found to be composed of a polypeptide of approximately 46 mer. This component was identical in sequence to the N-terminal portion of a hypothetical 153-residue protein encoded by the FLJ20513 gene cloned from the human KATO III cell line. That the amyloid protein was derived from this larger molecule was demonstrated by reverse transcription-polymerase chain reaction amplification of tumor-cell RNA where a full-length FLJ20513 transcript was found. Furthermore, immunohistochemical analyses revealed that the amyloid within the CEOTs immunostained with antibodies prepared against a synthetic FLJ20513-related dodecapeptide. Our studies provide unequivocal evidence that CEOT-associated amyloid consists of a unique and previously undescribed protein that we provisionally designate APin.

[The study of the invasive biologic behavior of ameloblastoma]

OBJECTIVE

To investigate the invasive biologic behavior of ameloblastoma (AB) and to analyze its correlative factors.

METHODS

The specimens of 43 cases of AB (primary AB 16 cases, recurrent AB 21 cases, malignant AB 6 cases) were examined immunohistochemically using the streptavidin-biotin method to determine the expression of E-cadherin (E-cad), matrix metalloproteinase (MMP)-2, MMP-9 and vascular endothelial growth factor (VEGF).

RESULTS

The cells in malignant AB scattered more, grew invasively, and the basal membrane ruptured or lost. The expression of E-cad in AB descended, MMP-2 and MMP-9 were strongly expressed in the epithelia cells of 28/41, 30/43 cases of AB, respectively. The positive rate and intensity of VEGF increased as AB recurred and transformed malignantly. The expression of E-cad, MMP-9 and VEGF were related to recurrence or malignant transformation of AB (r(s) = 0.309, 0.519, 0.381, P < 0.05).

CONCLUSION

AB is a high invasive tumor. The biological behavior of AB is related to lost or abnormal expression of E-cad, the high expression of MMP-2, MMP-9, and VEGF.

[Expression of matrix metalloproteinases and tissue inhibitor of metalloproteinase in ameloblastoma]

OBJECTIVE

To study the expression of matrix metalloproteinase(MMP) and tissue inhibitor of metalloproteinase (TIMP) in ameloblastoma (AB) and to determine the relationship between biological behavior of AB and clinical pathology.

METHODS

The specimens of 43 cases of AB, 10 cases of odontogenic keratocyst (OKC), 8 cases of normal oral mucosa were examined by streptavidin-biotin method.

RESULTS

In 8 cases of normal oral epithelial, MMP-2 was negative or weak positive. In OKC, MMP-2 was extensively positive in stratum spinosum of 2 cases, and weekly or negative in stratum basale. MMP-2 was strongly expressed in the central and peripheral cells of the tumor islands in 28 cases of AB. There were difference among these three groups (P < 0.001). Comparing AB with normal oral mucosa and OKC, there was significant difference (P < 0.05). MMP was positive expressed in cells of stroma. The positively rate and intensity increased as AB recurrence and transformed malignantly, but were not associated with age, sex, pathological type and location. TIMP-1 was weakly or not expressed in normal oral mucosa, stoma, OKC and AB.

CONCLUSIONS

The high expression of MMP-2 and MMP-9 is related to the biological behavior of AB. Imbalances of the expression of MMP-2 and MMP-9 protein maybe be one of the facts of the invasion of AB. The MMPs activation produced by stromal cells may be also be related to the invasion of AB.

beta-Catenin is expressed aberrantly in tumors expressing shadow cells. Pilomatricoma, craniopharyngioma, and calcifying odontogenic cyst

We studied the beta-catenin immunohistochemical profile in tumors expressing shadow cells: pilomatricoma, 10 cases; calcifying odontogenic cyst, 6 cases; and craniopharyngioma, 9 cases. There was strong membranous, cytoplasmic, and nuclear staining of the immature basaloid cells in all of these tumors. Shadow cells were negative in all tumors. It has been documented that rising levels of free beta-catenin drive the formation of complexes with T-cell factor/lymphoid enhancer factor (TCF-Lef) and up-regulate the wingless-Wnt cell-cell signals. The end result is an abnormality of beta-catenin degradation and, thus, a buildup of free beta-catenin in the cytoplasm and/or nucleus, resulting in the stimulation of cellular proliferation and/or inhibition of cell death. beta-Catenin seems to have an important role in the oncogenesis of these tumors. The similar pattern of keratinization in these tumors and the similar pattern of beta-catenin immunoreactivity in the cytoplasm and the nucleus are important findings. It seems that the activation of a common cellular pathway, namely Wnt-beta-catenin-TCF-Lef, has a role in the pathogenesis of these tumors. The latter could be related to their shared method of keratinization or shared dysfunction of the cellular adhesion complex leading to tumorigenesis.

[Expression of telomerase and p53 in ameloblastoma]

OBJECTIVE

To detect the expression of p53 protein, hTR, and hTERT mRNA in ameloblastoma (AB) and to investigate the clinical biological characteristics of AB.

METHODS

We detected hTR and hTERT Mrna in 54 cases of AB by in situ hybridization, and p53 protein by S-P method.

RESULTS

The positive ratio of hTR, hTERT mRNA was 2/7 and 1/7 in normal oral mucosa, 81.2%(13/16) and 87.4% (14/16) in odontogenic keratocyst (OKC), 94.4%(51/54) in AB, respectively. There was a significant difference in these three groups (P < 0.001). A strong correlation between hTR and hTERT mRNA was found (rs = 1.000, P < 0.001). p53 protein was expressed in 87.5% (42/49) AB, 44%(11/25) OKC, 33.3%(1/3) normal oral mucosa, respectively. A strong correlation between hTERT mRNA and p53 protein was found (rs = 0.848, P < 0.001). A moderate correlation between hTR mRNA and p53 protein was found (rs = 0.536, P < 0.001).

CONCLUSION

The positive ratios of hTR and hTERT were higher than p53 protein in AB. Telomerase activity and p53 expression play an important role in genesis and development of AB.

Ameloblastic carcinoma in a horse

The clinical, gross morphological, histological and immunohistochemical characteristics of an ameloblastic carcinoma in a 30-year-old Quarter Horse mare are reported. This tumour was fast growing, locally invasive and destructive. Histologically, it showed an infiltrative pattern of large islands, broad sheets and, at the periphery, small cords of moderately pleomorphic round, oval to spindle-shaped cells. Immunohistochemical evaluation revealed positive labelling for vimentin, cytokeratin 5/6 and cytokeratin 14. In the oral cavity of human beings, this immunolabelling pattern is unique for the embryonal enamel organ and tumours of ameloblastomatous epithelial origin, which strongly supports the diagnosis of equine ameloblastic carcinoma.

Epidermal growth factor receptor expression in ameloblastoma

Ameloblastoma is a locally aggressive tumor with possible lethal potential. Currently extensive surgery is the most acceptable treatment modality.

AIM

To investigate the presence of EGFR in ameloblastoma in order to consider using newly developed anti-EGFR therapeutic agents in cases of unresectable tumors. The study consisted of 58 formalin-fixed, paraffin-embedded specimens of ameloblastoma that were immunohistochemically stained with a monoclonal anti-EGFR antibody (clone 31G7). Positive and negative controls determined specificity of the antibody. A staining score based on the staining intensity and the proportion of stained cells was established, ranging between 0 and 2. All specimens were EGFR positive; 8 (14%) exhibited the maximum score of 2 and 19 (33%) scored between 1 and 2. Since ameloblastomas are EGFR-positive tumors, anti-EGFR agents could be considered to reduce the size of large tumors and to treat unresectable tumors that are in close proximity to vital structures.

Proliferating cell nuclear antigen and Ki67 immunoreactivity in ameloblastomas

OBJECTIVE

This study used proliferating cell nuclear antigen (PCNA) and Ki67 to evaluate and compare the in situ proliferative activity of (1) solid and multicystic and (2) unicystic ameloblastomas in an attempt to provide a scientific basis for any differences in biologic behavior that exists between these 2 groups of lesions.

STUDY DESIGN

Twenty archival tissue sections, 10 of primary unicystic and 10 of solid and multicystic ameloblastomas, were immunohistochemically stained with PCNA and Ki67 antisera. Immunoreactivity was evaluated by the counting of cells, and the data obtained were statistically analyzed.

RESULTS

The results showed that cellular proliferative activity varied within the ameloblastoma types. The unicystic ameloblastomas showed statistically significantly higher PCNA and Ki67 labeling indices than the solid and multicystic variant.

CONCLUSION

There appears, therefore, to be no correlation between proliferative activity as shown by these proteins and reported biologic behavior.

Spindle-cell ameloblastic carcinoma: A case report with immunohistochemical, ultrastructural, and comparative genomic hybridization analyses

Spindle-cell ameloblastic carcinoma is a classification proposed for a group of rare odontogenic carcinomas with sarcomatoid components and is distinguished from odontogenic carcinosarcoma. We report a case of spindle-cell ameloblastic carcinoma of the right mandible that occurred in a 67-year-old Japanese man. Growth of the tumor was destructive, there was extensive lung metastasis, and the outcome was unfavorable. Ultrastructural and immunohistochemical examination showed the spindle-cell component of the tumor to be epithelial in character. A gain of 5q with amplification of 5q13 was detected in the tumor by comparative genomic hybridization.

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.

A clinicopathologic and immunohistochemical analysis of melanotic neuroectodermal tumor of infancy

OBJECTIVE

The purpose of this study was to review the features of 8 cases of melanotic neuroectodermal tumor of infancy (MNTI) of the jaws with respect to the expression of NB84, CD99, PGP 9.5, specific cytokeratins, and Ki-67, markers not previously reported in this entity.

STUDY DESIGN

A clinicopathologic and immunohistochemical analysis of MNTIs in 8 children was undertaken.

RESULTS

Patients were aged 2(1/2) months to 14 months. Seven were males. Seven lesions affected the maxilla. Microscopically, collections of larger, melanocyte-like cells were admixed with smaller, neuroblast-like cells. All MNTIs contained melanin; although most showed cellular atypia, mitoses were infrequent (<2 per 10 high-power fields). However, in one lesion in which the melanocyte-like cells appeared less differentiated, 7 mitoses per 10 high-power fields were counted. The larger cells expressed cytokeratins 7 (4/8), 8 (8/8), 18 (6/8), and 19 (3/8); PGP 9.5; neuron-specific enolase (6/8); S100; HMB45; and chromogranin A (2/8). The small cells expressed CD56 (7/8), neuron-specific enolase (7/8), synaptophysin (3/8), PGP 9.5 (3/8), and chromogranin A (2/8). No MNTIs expressed NB84. The most mitotically active tumor was the only one to show membrane expression of CD99 (by both cell populations), have a detectable Ki-67-positive fraction (25% in both the large- and small-cell components), behave aggressively, and require bilateral maxillectomy. All other MNTIs responded to local excision, and none metastasized.

CONCLUSIONS

Most MNTIs are benign and respond to conservative excision. Histology is an unreliable means of predicting clinical behavior, but this study has identified some morphologic and phenotypic features that may indicate a more aggressive lesion.

Different keratin profiles in craniopharyngioma subtypes and ameloblastomas

Craniopharyngiomas are generally considered to arise from the remnants of Rathke's pouch or a misplaced enamel organ. We tried to refine these hypotheses, comparing the subtypes of craniopharyngioma with Rathke's cleft cyst, a known Rathke's pouch derivative, and with ameloblastoma, an enamel organ derivative. Nineteen craniopharyngiomas (14 adamantinomatous and 5 papillary type tumors) and 17 ameloblastomas were immunostained for cytokeratin (CK) 7, CK 8, CK 14, and human hair keratin (HHK). All cases of adamantinomatous craniopharyngioma were CK 7+/CK 8+/CK 14+. Two cases (40%) of papillary craniopharyngioma were CK 7+/CK 8+/CK 14+, whereas the remaining three cases (60%) were CK 7+/CK 8-/CK 14+. Fifteen cases (88%) of ameloblastoma were CK 7-/CK 8+/CK 14+. Only the shadow cells present in adamantinomatous craniopharyngiomas were positive for HHK, which may indicate their follicular differentiation. In Rathke's cleft cyst, ciliated cuboidal cells were CK 7+/CK 8+/CK 14- and metaplastic squamous cells were CK 7+/CK 8/CK 14+. These findings suggest that both subtypes of craniopharyngioma may differ from ameloblastoma in histogenesis, although cytokeratin expression patterns may change during tumor development. Adamantinomatous craniopharyngioma may be related to a heterotopic ectodermal tissue which can differentiate into hair follicles, while papillary craniopharyngioma may arise from Rathke's cleft cyst.

[Proliferating activity and differentiation between peripheral cells and central cells in ameloblastoma]

OBJECTIVE

To investigate the proliferating activities and differentiation between peripheral cells and central cells in ameloblastoma.

METHODS

Expressions of proliferating cell nuclear antigen (PCNA), Ki-67, CK10&13 and CK19 were detected in 43 ameloblastoma (15 follicular, 20 plexiform and 8 acanthomatous) by SP immunohistochemical methods.

RESULTS

The PCNA labelling indices were significantly higher in peripheral cells (5.12% +/- 2.76%) of tumour nests or strands than in central cells (1.36% +/- 1.02%, P < 0.001). The peripheral cells of tumour nests or strands exhibited a significantly higher Ki-67 labelling index (3.63% +/- 1.80%) than central cells (1.26% +/- 0.96%, P < 0.001). The labelling indices between PCNA and Ki-67 showed a significant correlation (P < 0.01). The positive expressions of CK10&13 and CK19 were significantly higher in central cells than in peripheral cells (P < 0.01).

CONCLUSIONS

The peripheral zones of tumour nests or strands are regarded as proliferating areas; there exists a significantly different differentiation between central cells and peripheral cells.

Histopathological and immunohistochemical analysis of calcifying odontogenic cysts

METHOD AND RESULTS

Calcifying odontogenic cysts (COCs) were examined histopathologically and immunohistochemically to characterize the histological and cytological properties of these lesions. Histopathologically, COCs showed thin or thick lining epithelium with ghost cells. COCs were classified according to proliferative type or nonproliferative type lining epithelium, the presence or absence of ameloblastomatous appearance, and the presence or absence of odontoma in the cyst walls. Immunohistochemically, amelogenin protein was expressed chiefly in ghost cells, whereas cytokeratin 19 (CK19) and bcl-2 proteins were expressed chiefly in lining epithelial cells. The proportion of cases positive for bcl-2 protein was slightly higher in COCs with odontoma than in those without odontoma. Lining epithelial cells sporadically showed positive reactions for Ki-67 antigen. Mean Ki-67 labeling index was slightly greater in COCs with proliferative type lining epithelium, COCs with ameloblastomatous appearance of the cyst walls, and COCs with odontoma of the cyst walls than in COCs without these histological features. Our results suggest that ghost cells or lining epithelial cells show ameloblastic cytodifferentiation or odontogenic epithelial characteristics, that bcl-2 protein is associated with survival of lining epithelial cells in COCs, and that high proliferation potential is associated with ameloblastomatous proliferation or combined odontoma. COCs exhibited various histological features with several transitional forms, and immunohistochemical examinations revealed little or no difference in cytodifferentiation and cellular activity among COCs.

CONCLUSION

We conclude that COCs with various histological features have neoplastic potential and may not be separate entities within the same histological spectrum.

Clear-cell odontogenic carcinoma with pulmonary metastases resembling pulmonary meningothelial-like nodules

Clear-cell odontogenic carcinoma (CCOC) is a rare neoplasm with malignant potential and unknown cytogenetic alterations. We describe the case of a 43-year-old woman who presented with an unusual odontogenic epithelial tumor. Histologically, the tumor was composed of clear-cell areas and exhibited a squamous pattern with little nuclear pleomorphism similar to benign squamous odontogenic tumor. Multiple small pulmonary nodules occurring 3 years after primary surgical treatment histologically closely resembled benign minute pulmonary meningothelial-like nodules (MPMN) with clear-cell features. Comparative genomic hybridization (CGH) and immunohistochemistry, performed as diagnostic adjuncts, revealed in the odontogenic tumor and the pulmonary lesions a very similar pattern of chromosomal aberrations (loss of 9, gains of 14q, 19 and 20 in both, and additional loss of 6 in the odontogenic tumor) and the same pattern of expression (positive for cytokeratin 5, 6, 8, 19 and negative for cytokeratin 18, epithelial membrane antigen, and vimentin), differing from that of MPMN. These findings confirmed the final diagnosis of metastasizing CCOC with partial squamous differentiation, substantiated the unfavorable prognosis of the clear-cell component, and highlighted the diagnostic impact of CGH and immunohistochemistry for classification of these morphologically peculiar pulmonary CCOC metastases.

Primary non-Hodgkin's lymphoma of the jaws: immunohistochemical and genetic review of 10 cases

PURPOSE

Non-Hodgkin's lymphoma (NHL) comprises a group of malignant lymphoproliferative diseases characterized by clonal expansion of lymphocytes at various levels of ontogenetic development. The aim of this study was to review the immunohistochemical and cytogenetic features of 10 cases of NLH of the jaws to determine their respective derivation.

PATIENTS AND METHODS

Histopathologic and immunohistochemical review of 10 cases of large-cell lymphomas of the jaws, together with Southern blot analysis of 2 of the cases, was performed and results compared with the findings in the literature.

RESULTS

In the 10 cases studied, the average age of onset of the NHL was 51 years, with a male-to-female ratio of 3:2. Tumefaction was the first clinical sign of disease. Eight of 10 cases were high-grade, large-cell NHLs, centroblastic type. Two cases were high-grade, large-cell NHL, immunoblastic type.

CONCLUSION

The immunohistochemical and Southern blot data remain the principal laboratory aids in the diagnosis and characterization of NHL, and they provide critical information for guiding clinicians to the appropriate treatment protocol for these malignancies.

CK13 in craniopharyngioma versus related odontogenic neoplasms and human enamel organ

The monoclonal antibody NCL-CK13 was studied in specimens of craniopharyngioma, ameloblastoma and calcifying odontogenic cyst neoplasms and the mandible and maxillae of normal human fetuses. There was a decrease in NCL-CK13 as the dental lamina developed, with a complete loss in the enamel organ. The neoplastic epithelia of the neoplasms revealed a clear phenotypic and immunohistochemical reactive relationship to the stratified embroyonic mucosa, away from the enamel organ. This suggests that these neoplasms might have their histogenesis from early stage epithelium, the oral part of the dental lamina or its remnants.

An immunohistochemical study of keratin expression in ameloblastoma from a Kenyan population

OBJECTIVES

Ameloblastomas appear to exhibit biological heterogeneity and, except in the case of malignancy, histological appearances that do not always allow their behaviour to be predicted. The aim of this study was to assess keratin expression in African ameloblastomas and to correlate this with their clinical and histological features.

MATERIALS AND METHODS

Expression of simple keratins 7, 8, 18 and 19; cornification keratins 1 and 10; basal and differentiation keratins 5 and 14 and hyperproliferation-related keratins 6 and 16 in 14-39 cases of ameloblastoma was assessed by immunohistochemical methods.

RESULTS

There was patchy expression of keratin 7 in the suprabasal and stellate reticulum-like cells in some cases. All cases showed similar weak expression for keratins 8 and 18 in suprabasal and stellate reticulum-like cells but none showed keratin 1 or 10 expression. There was intense expression of keratins 5, 14 and 19 by all tumour cells suggesting that they may retain basal cell characteristics with a potential for proliferation. No consistent relationship was seen between histological types and keratin expression pattern. However, keratins 6 and 16, expressed by suprabasal and stellate reticulum-like cells, showed a marked variation within and between cases, with the highest levels of expression in squamous strands.

CONCLUSIONS

We propose that squamous strands may represent the sites of most active growth within individual tumours and expression of keratins 6, 16 and 19 may be predictors of rapid growth. There is a need for further investigation of this in longitudinal clinical studies.

Immunohistochemical expression of p53, MDM2, Ki-67 and PCNA in central giant cell granuloma and giant cell tumor

Central giant cell granuloma (CGCG) is a reactive bone lesion that occurs mainly in the jaws. The giant cell tumour (GCT) is a benign locally aggressive neoplasm located near the articular end of tubular bones. Both lesions are characterised histologically by multinucleated giant cells in a background of ovoid to spindle-shaped mesenchymal cells. There is a basic question whether both lesions are separate entities or variants of the same disease. The study of cell cycle-associated proteins may give insights into clarifying such question. The expression of these proteins is also important to determine the cell cycle regulation in both tumours. The purpose of this study was to evaluate the immunohistochemical expression of p53, MDM2, Ki-67 and PCNA in CGCG and GCT. The results demonstrated that, despite the lack of p53 immunoreactivity, all the samples showed wide expression of MDM2. The percentage of Ki-67- and PCNA-positive cells in CGCG was statistically higher than that of GCT Our findings show that CGCG has a higher proliferative activity compared with that of the GCT. Our results also suggest that p53 inactivation by MDM2 expression may be involved in the pathogenesis of giant cell lesions of the jaws and long bones.

In situ hybridisation and immunocytochemical localisation of osteolytic cytokines and adhesion molecules in ameloblastomas

Ameloblastomas produce interleukin-1-like activity that could explain some part of their osteolytic capability. However, the cellular source of this osteolytic activity is unknown. In the present study, cytokines with known inflammatory and osteolytic activity, i.e., interleukin-1 (IL-1), tumour necrosis factor (TNF), and interleukin-6 (IL-6), have been localised by immunocytochemistry and in situ hybridisation. The cellular adhesion receptors ICAM-1, E-selectin and VCAM-1 have also been immunolocalised. Immunocytochemistry demonstrated that all seven specimens showed positive staining for IL-1alpha and IL-6 with these cytokines being located in the stellate reticulum-like cells and vascular endothelium. Very faint staining for IL-1beta was seen in four of seven specimens. No reaction was seen for TNF-alpha. All specimens demonstrated E-selectin staining in the vascular endothelium and ICAM-1 and VCAM-1 staining in the stellate reticulum-like cells and the endothelium. In situ hybridisation for the cytokines showed the presence of mRNA of both IL-1alpha and IL-6 in the stellate reticulum-like cells. Faint staining for IL-1beta was also seen. No staining was seen for TNF. These findings show that ameloblastomas synthesize two bone-modulating cytokines, IL-1alpha and IL-6, and that these are synthesized mainly by the stellate reticulum-like cells. These tumours also contain a proportion of activated blood vessels in which endothelial cells express the cellular adhesion receptors ICAM-1, E-selectin and VCAM-1.

Calcifying odontogenic cyst: a clinicopathologic study of 57 cases with immunohistochemical evaluation for cytokeratin

PURPOSE

A clinicopathologic study of all cases accessioned as calcifying odontogenic cyst (COC) from 1971 to 1996 from the files of the Oral Pathology Laboratory at Temple University School of Medicine was undertaken.

MATERIALS AND METHODS

Microscopic slides and clinical histories of cases diagnosed as calcifying odontogenic cyst were reviewed and analyzed. Ten cases were processed for cytokeratin immunohistochemical staining.

RESULTS

Fifty-seven cases were reviewed, 28 males and 29 females. Patients' ages ranged from 7 to 83 years, with a mean age of 49.8 years. Thirty-four cases involved the mandible and 23 were from the maxilla. Seventeen were reported in peripheral locations, and 38 occurred centrally within the jaws. Two were found both centrally and peripherally. The most common clinical sign for central lesions was a radiolucency sometimes associated with a jaw expansion. The most common clinical complaint for peripheral lesions was a nodular growth on the gingiva. Although lining epithelial cells were strongly positive for cytokeratin, full-brown ghost cells and disintegrating ghost cells were nonreactive.

CONCLUSION

Calcifying odontogenic cyst can occur in any age-group, intraosseously or extraosseously, and as a solid lesion. No recurrences were found after surgical removal in the current series.

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.

Transferrin receptor in oral tumors

The transferrin receptor (TfR) appears in vigorously proliferating cells. We did an immunohistochemical study of TfR in oral tissues and a quantitative analysis by flow cytometry of TfR in a cancer cell line after an anticancer drug treatment. TfR was found in the parabasal and basal layers of the normal epithelium, but rarely in benign tumors. Generally, in the malignant tumors, the poor prognostic cases showed strong staining regardless of the differentiation of the tumor. In the flow cytometric analysis, the amount of TfR decreased according to the reduction of the proliferative ability of cancer cells. These results suggest that TfR expression may be useful as a prognostic marker.

The so-called calcifying epithelial odontogenic tumour in dogs and cats (amyloid-producing odontogenic tumour)

This paper describes the microscopical features of a rare odontogenic tumour that occurs in dogs and cats and which has been referred to as the calcifying epithelial odontogenic tumour (CEOT), although it is not the counterpart of the human tumour of that name. We have proposed amyloid-producing odontogenic tumour (APOT) as an appropriate alternative term. The tumour is composed of irregularly shaped strands of squamous epithelium, which in some areas exhibit palisading of the basal cells, similar to that seen in ameloblastomas. Stellate reticulum occurs focally in some examples. The second prominent feature is the presence of amyloid which tends to calcify. Finally, in some examples, a collagenous matrix, which is apparently a form of dentine, is present focally, adjacent to the epithelium. These histological features are compared with those of the canine keratinizing ameloblastoma and the human CEOT. To date, to few examples have been reported to determine accurately the biological behaviour of APOTs, but some have recurred after excision; none has metastasized.

[In situ hybridization and immunohistochemical detection of bone morphogenetic protein genes in ameloblastomas]

Bone morphogenetic protein (BMP) is related to the formation of bone and dentin. Immunohistochemical study showed that ameloblasts, odontoblasts and dental papilla cells contained much BMP. It is indicated BMP might be associated with the epothelial-mesenchymal interaction of tooth germs. In this study, the expression and distribution of BMP in 40 patients with ameloblastomas were observed by using in situ hybridization and immunohistochemistry. The results showed that all three BMP genes were overexpressed in the epithelial component of ameloblastomas, however, no positive reaction was found in immunohistochemistry. It is indicated that overexpression of BMP genes might be related to the development of ameloblastomas.

[The determination of polyamines in tumors of the maxillofacial area]

Putrescine, spermidine and spermine are polyamines deriving from ornithine. These are vital molecules for cell duplication processes; in fact, enzyme inhibitors responsible for synthesis are able to block cell multiplication. It is interesting to observe that there is an increased concentration of the polyamines and enzymes responsible for synthesis in solid tumours in man and in biological fluids in subjects carrying tumours. The authors assayed the polyamine concentration in tumour tissue taken from 10 cases of parotid carcinoma, noting a considerable increase in their levels compared to healthy control tissues. The hypothesis of being able to use the level of polyamines present in biological fluids in order to make an early diagnosis of tumours has now been definitively abandoned, both due to the scarce specificity and sensitivity of the available methods and due to the fact that increased polyamine concentrations were also found in physiological conditions and in the presence of non-tumour diseases; however, it is now being examined whether it would be possible to use polyamine levels to assess the degree of biochemical tumour malignancy or to evaluate the response to surgical or pharmacological treatment in patients with malignant tumours.

Patterns of expression of intermediate filaments and S-100 protein in desmoplastic ameloblastoma

Seventeen cases of desmoplastic ameloblastoma were examined immunohistochemically. Immunoperoxidase techniques were applied for detection of keratin, desmin, vimentin and S-100 protein expression in these tumors. The tumor epithelium of desmoplastic ameloblastoma exhibited weak, focal, inconstant keratin staining, weak, variable expression of S-100 protein, desmin immunoreactivity of mild to moderate intensity and vimentin non-reactivity. The pertinent literature on the immunohistochemistry of ameloblastomas is briefly reviewed.

Epidermal growth factor receptor in odontogenic cysts and tumors

The expression of epidermal growth factor receptor (EGFR) was investigated in 67 cases of odontogenic cysts and 35 cases of odontogenic tumors using monoclonal antibody to EGFR (Biomarker, Israel) to determine the presence and significance of this transmembrane growth factor receptor. The cystic epithelial cells of odontogenic cystic lesions (keratocyst 60%; primordial cyst 75%; radicular cyst 35%; and follicular cyst 47.4%) were positive to EGFR staining. Cytochemical characterization of EGFR in those cystic epithelium was cell membrane positive type as in the normal epithelium. No expression of EGFR was found in the odontogenic tumors. This diversity of EGFR represents no binding activity of EGF, or loss of EGFR in the tumor cell upon EGFR mediated growth in odontogenic tumors was suggested a different tumor cell growth factor status or microenvironment in cell proliferation mechanism at the cellular level in cysts and tumors of odontogenic origin.

Comparative immunohistochemical analysis between jaw myxoma and mesenchymal cells of tooth germ

The histogenesis of jaw myxoma is still debated. According to some authors it arises from the primitive mesenchymal components of developing teeth. In this study, we have studied the expression of S-100 protein and vimentin in dental follicle, dental papilla and periodontal ligament cells using monoclonal and polyclonal antibodies. Myxoma of the jaw expresses vimentin and S-100 protein. On the contrary, as compared to jaw myxoma, the normal developmental structures were immunonegative for S-100 protein but stained for vimentin. These results could indicate a difference in the derivation other than tooth mesenchyma.

Peripheral odontogenic fibroma: a clinicopathologic study

The clinicopathologic features of 30 cases of peripheral odontogenic fibroma are reviewed. The age distribution is wide (11 to 76 years), and there is a slight predilection for males. The majority of the lesions (93%) occurred in blacks on the attached gingiva, and with equal frequency in the maxilla and mandible. Size varied between 1 and 3 cm in diameter. One case recurred after 14 months. Histologically, the lesions are nonencapsulated and poorly delineated. The amount of odontogenic epithelium varies considerably and consists usually of small islands or strands, although larger follicles are sometimes present. In one case the epithelial cells had a clear cytoplasm, whereas in another it was granular and eosinophilic. Origin from the surface oral mucosa can sometimes be seen. The connective tissue component is usually cellular, but collagenous, myxomatous, and mixed forms occur. Calcifications were present in 22 cases and consisted of tissue interpreted as either dentinoid, cementum, bone, or dystrophic calcific material.

Lectin histochemistry of cystic jaw lesions: an aid for differential diagnosis between cystic ameloblastoma and odontogenic cysts

The binding sites for Ulex europaeus agglutinin I (UEA-I), Bandeirea simplicifolia agglutinin I (BSA-I), and peanut agglutinin (PNA) were comparatively examined in the surgical materials from 41 cases of cystic and solid ameloblastomas and 42 cases of non-neoplastic odontogenic cysts including dentigerous cyst, odontogenic keratocyst, and radicular cyst. In non-neoplastic cysts, most of epithelial lining layers gave positive binding with UEA-I and BSA-I. However, no positive reactions were obtained for these two lectins in the epithelial components of ameloblastoma, except for limited UEA-I binding to markedly keratinized tumor cells in four cases. PNA binding was irregular and did not make any clear distinction between ameloblastomas and cysts. The results suggest that the lectin staining for UEA-I and BSA-I is a useful histologic aid for differential diagnosis between cystic ameloblastoma and non-neoplastic jaw cysts.