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.

Comparative histological and immunohistochemical study of ameloblastomas and ameloblastic carcinomas.

BACKGROUND: This study aimed to compare the histological and immunohistochemical characteristics of ameloblastomas (AM) and ameloblastic carcinomas (AC). MATERIAL AND METHODS: Fifteen cases of AM and 9 AC were submitted to hematoxilin and eosin (H&E) and immunohistochemical analysis with the following antibodies: cytokeratins 5,7,8,14 and 19, Ki-67, p53, p63 and the cellular adhesion molecules CD138 (Syndecan-1), E-cadherin and ß-catenin. The mean score of the expression of Ki-67 and p53 labelling index (LIs) were compared between the groups using the t test. A value of p<0.05 was considered to be statistically significant. RESULTS: All cases were positive for CKs 5, 14 and 19, but negative for CKs 7 and 8. CKs 5 and 19 were positive mainly in the central regions of the ameloblastic islands, while the expression in AC was variable in intensity and localization. CK14 was also variably expressed in both AM and AC. Ki-67 (P=.001) and p53 (P=.004) immunoexpression was higher in AC. All cases were positive for p63, but values were higher in AC. CD138 was mainly expressed in peripheral cells of AM, with a weak positivity in the central areas, while it was positive in most areas of ACs, except in less differentiated regions, where expression was decreased or lost. E-cadherin and ß-catenin were weakly positive in both AM and AC. CONCLUSIONS: These results shows that Ki-67, p53 and p63 expression was higher in AC as compared to AM, suggesting that these markers can be useful when considering diagnosis of malignancy, and perhaps could play a role in malignant transformation of AM. Pattern of expression of CKs 5 and 19 in AC were different to those found in AM, suggesting genetic alterations of these proteins in malignant cells. It was confirmed that CK19 is a good marker for benign odontogenic tumors, such as AM, but it is variably expressed in malignant cases.

Lichen sclerosus of the oral mucosa: clinicopathological features of six cases.

Lichen sclerosus is a chronic inflammatory mucocutaneous disease, rarely involving the mouth. There are only 20 well-documented cases of oral lichen sclerosus reported in the English-language literature. This report describes the clinicopathological features of 6 cases of oral lichen sclerosus; 5 in women. There were 12 lesions, mainly on the lips (50%) and buccal mucosa (25%). The affected areas appeared as irregular whitish patches, harder than the surrounding tissue. Half of the patients were symptomatic and presented with no associated skin and/or genital lesions. All cases were biopsied, and histopathological features were evaluated using hematoxylin-eosin and Verhoeff's stains, S-100 immunohistochemical reaction and transmission electron microscopy. Management of the oral lesions consisted of surgical excision, intralesional triamcinolone acetonide, oral colchicine, and regular follow-up. There is no effective curative treatment, but there are some options for patient management; and colchicine may be considered an additional choice.

Ameloblastomas: a regional Latin-American multicentric study.

AIM: To classify 163 ameloblastoma cases according to the new WHO Classification of Odontogenic Tumours (2005) and analyse their clinical and microscopic features. METHODS: We studied the clinico-pathological features of 163 ameloblastoma cases from nine regional Latin-American institutions from Mexico and Guatemala. RESULTS: Ameloblastomas comprised 22.7% of all odontogenic tumours. The mean age was 41.4 years for solid ameloblastoma (SA) and 26.3 years for unicystic ameloblastoma (UA) (P < 0.001) and both sexes were almost equally affected. The mandible was mainly affected for both UA and SA. The mean size was 6.2 cm for SA and 6.3 cm for UA cases. The recurrence rate was 21.7% for SA and 12.6% for UA. UA was twice as more frequent than the solid variant. CONCLUSIONS: In this study we found that UA was frequently misdiagnosed as SA; however, there are enough clinical and microscopic features that allow for an accurate differentiation between both types of ameloblastoma that should be recognized for surgical and prognostic purposes. In this study, SA was not found in patients younger than 20 years, UA had a constant myxoid stroma while mature connective tissue was more frequently associated with the solid type.

Oral leishmaniasis: a clinicopathological study of 11 cases.

Leishmaniasis is a parasitic disease with diverse clinical manifestations, and considered a public health problem in endemic countries such as Brazil. Mucosal lesions usually involve the upper respiratory tract, with a predilection for nose and larynx. Oral involvement is unusual and in most cases it becomes evident after several years of resolution of the original cutaneous lesions. Oral lesions classically appear as mucosal ulcerations, mainly in the hard or soft palate. This report describes the clinicopathological data of 11 cases of mucocutaneous leishmaniasis with oral manifestations. Two cases of Leishmania (Viannia) braziliensis and one case of Leishmania (Leishmania) amazonensis were confirmed by polymerase chain reaction-restriction fragment length polymorphism or DNA sequencing in mucosal samples.

Adenomatoid dentinoma or adenomatoid odontogenic hamartoma: what is the better term to denominate this uncommon odontogenic lesion?

We report two cases of an uncommon odontogenic lesion, previously described as adenomatoid dentinoma. They were well-circumscribed unilocular radiolucent lesions exhibiting discrete radiopacities, located in the left mandibular third molar region. Microscopically they were composed of odontogenic hard and soft tissues, similar to a dental germ. Dental papilla and dentin were easily identified. Odontogenic epithelium formed adenomatoid-like structures, and by scanning electron microscopy a layer of enamel was seen in contact with the dentin. Based on these clinical, radiographic, histological and electron microscopical features we proposed the diagnosis of adenomatoid odontogenic hamartoma. Treatment consisted of surgical removal, and no recurrence was observed. In our opinion all similar cases previously reported pertain to the same spectrum of this lesion and thus should be named as suggested above. Moreover, ultrastructural observations using 5 microm sections can be useful to better characterize the presence of hard tissues.

Extranodal head and neck lymphomas in Guatemala: high frequency of Epstein-Barr virus-associated sinonasal lymphomas.

Sinonasal lymphomas of T cell or natural killer cell (T/NK cell) phenotype represent a subset of extranodal head and neck lymphomas. T/NK cell sinonasal lymphomas have been described in diverse geographic settings, including China, Japan, Peru, Northern Europe, and North America. The frequency of these lymphomas is highly dependent on the geographic location in which they occur, their incidence being low in Europe and North America and relatively high in Asian countries and in Peru. Regardless of their geographic location, they are typically associated with the Epstein-Barr virus (EBV). Few studies have addressed the relative frequency of sinonasal lymphoma within the group of extranodal head and neck lymphomas. We investigated the anatomic distribution, immunophenotypical profile, and EBV status of 33 cases of extranodal head and neck lymphoma from patients in Guatemala. The anatomic distribution of these lymphomas is similar to that seen in Asian countries: 17 (52%) in the sinonasal area, five (15%) in the palate, and 11 (33%) in other locations. Fifteen (88%) of the 17 sinonasal lymphomas showed a T or null cell phenotype with a strong association with EBV by in situ hybridization. Most Guatemalan patients with these lymphomas were of Mayan descent. In Guatemala, the relative frequency of sinonasal lymphomas within the group of head and neck lymphomas is significantly higher than that reported for Western countries. In addition, the relative frequency of T/NK versus B cell sinonasal lymphomas is higher than that described in North America and similar to that observed in Asian countries and Peru.