Primordial odontogenic tumour: clinicopathological analysis of six cases of a previously undescribed entity.

AIM: To describe the clinicopathological and immuno-histochemical features of six tumours that do not fulfil the criteria of any of the currently classified odontogenic tumours. METHODS AND RESULTS: The patients were three males and three females, whose ages ranged from 3 years to 18 years (mean, 11.05 years). In all cases there were well-defined radiolucencies associated with unerupted teeth apparently showing a pericoronal relationship. Microscopically, all tumours were composed of variably cellular loose fibrous tissue with areas similar to dental papilla, entirely surrounded by cuboidal to columnar epithelium resembling the internal epithelium of the enamel organ. Mesenchymal tissue was positive only for vimentin, and Ki67 expression was very low (<2%). The epithelium was positive for CK AE1/AE3, CK5, CK14, and CK19, but negative for CK18 and CK20. All cases showed clear demarcation from the surrounding bone, and were surgically removed, with no recurrences after follow-up ranging from 6 months to 20 years. CONCLUSIONS: These findings differ from those observed in other odontogenic lesions, such as ameloblastic fibroma, odontogenic myxoma, odontogenic fibroma, and hyperplastic dental follicles. The term primordial odontogenic tumour is proposed to describe this novel lesion.

Expression of PROX-1 in oral Kaposi's sarcoma spindle cells.

BACKGROUND: The histogenesis of neoplastic spindle cells of Kaposi's sarcoma is still uncertain, but some studies consider it a lymphatic vessel differentiation. Prox-1 is a nuclear transcription factor that plays a major role during embryonic lymphangiogenesis, and it has been considered a specific and sensitive lymphatic endothelial cell marker. The aim of this study was to determine the expression of Prox-1 in oral Kaposi's sarcoma comparing the results with oral benign vascular tumors including capillary hemangiomas and pyogenic granulomas. METHODS: Expression of Prox-1 and HHV-8 was evaluated by immunohistochemistry in 30 oral Kaposi's sarcoma, 5 oral capillary hemangiomas, and 10 oral pyogenic granulomas. The labeling index was expressed as the percentage of positive cells for each case studied. Statistical comparison was performed using the Wilcoxon-Mann-Whitney rank sum test. RESULTS: Twenty-eight (93.3%) and 30 oral Kaposi's sarcoma cases were positive for Prox-1 and HHV-8, respectively, while all oral benign vascular tumors were negative for these markers. The number of Prox-1 and HHV-8 oral Kaposi's sarcoma-positive cells increased significantly from patch/plaque to nodular histological stages. CONCLUSION: The expression of Prox-1 in the neoplastic spindle cells supports the view of a lymphatic differentiation in oral Kaposi's sarcoma. Prox-1 may also be involved in the pathogenesis of oral Kaposi's sarcoma as the number of positive spindle cells increased progressively from patch to nodular stages and could be eventually useful as an additional diagnostic tool for differential diagnosis between oral Kaposi's sarcoma and benign oral vascular lesions.

Central odontogenic fibroma: new findings and report of a multicentric collaborative study.

OBJECTIVE: The aim of this study was to describe the clinicopathologic and immunohistochemical characteristics of 14 cases of central odontogenic fibroma (COF), and the ultrastructural features of 2 of them. STUDY DESIGN: Collaborative retrospective study based on the records of 4 oral pathology diagnostic services in Latin America based on the current World Health Organization classification. RESULTS: There were 7 male and 7 female patients (mean age 31.8 years). Eight tumors occurred in the maxilla and 6 in the mandible. Thirteen cases were epithelium-rich and 1 epithelium-poor COF. Three were classified as hybrid COF with giant cell lesion. Mean size of the hybrid lesions were larger than pure COF (3.8 vs. 2.4 cm). Odontogenic epithelial islands were immunoreactive for cytokeratin (CK) AE1/AE3, CK5, CK14, CK19, and 34BE12 and negative for CK1 and CK18. Langerhans cells positive for S-100 and CD1a were found within the epithelial islands in 6/6 tested cases. CD68 was expressed in the giant cells of the hybrid lesions and in a few mononuclear cells of 2 cases of COF. Ki-67 index was <1% in all cases. In 6 tumors (42.8%), there were small globular eosinophilic droplets within the epithelial islands, which were positive for collagen type IV, and 9/13 cases (69.2%) were focally positive for smooth muscle actin. In addition to fibroblasts, myofibroblastic differentiation was found in the 2 cases studied ultrastructurally. CONCLUSIONS: Immunohistochemistry was useful to confirm the presence of epithelium and to exclude other central fibrous tumors. COF also contains a variable number of mast cells, Langerhans cells, and myofibroblasts, and further studies are needed to better understand the participation of these cells in COF histogenesis.

Angiomyxolipoma (vascular myxolipoma) of the oral cavity. Report of a case and review of the literature.

Angiomyxolipoma is a rare tumor characterized by a proliferation of adipose tissue associated with a myxoid stroma and multiple vascular channels. To date, ten cases of angiomyxolipoma located in subcutaneous tissue, spermatic cord and subungual area have been reported in the literature. We describe the clinical and histopathologic findings of the first case of intraoral angiomyxolipoma in a 12 year-old male, as well as the utility of immunohistochemistry as a useful tool in differential diagnosis of this particular lesion with respect to other benign and malignant lesions derived from adipose tissue.

Peripheral desmoplastic ameloblastoma: Histopathological and immunohistochemical profile of a case

In this study we present a rare case of peripheral desmoplastic ameloblastoma and discuss its clinical features, histopathology, and inmunoshistochemical profile.This article reports a new case of this unusual neoplasm in a 66 year-old woman in which the main complaint was an asymptomatic swelling located in the right body of mandible. Histopathological findings were similar to the two previously reported cases of this tumor. Positive immunohistochemical stain for laminin V and type IV collagen suggests an inductive effect of the epithelium over the strom a while the low index of p53 protein and Ki-67expression in epithelium and stromal cells, as well as CD138 uniform positive-stain in epithelial cells, support the benign biological behavior of this lesion. Including this new case, currently there are only three reports of this rare neoplasm. Reports of new cases of peripheral desmoplastic ameloblastoma are necessary for a better understanding of the origin and behavior of this particular subtype of ameloblastoma (AU)

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Peripheral desmoplastic ameloblastoma: histopathological and immunohistochemical profile of a case.

In this study we present a rare case of peripheral desmoplastic ameloblastoma and discuss its clinical features, histopathology, and immunohistochemical profile. This article reports a new case of this unusual neoplasm in a 66 year-old woman in which the main complaint was an asymptomatic swelling located in the right body of mandible. Histopathological findings were similar to the two previously reported cases of this tumor. Positive immunohistochemical stain for laminin V and type IV collagen suggests an inductive effect of the epithelium over the stroma while the low index of p53 protein and Ki-67 expression in epithelium and stromal cells, as well as CD138 uniform positive-stain in epithelial cells, support the benign biological behavior of this lesion. Including this new case, currently there are only three reports of this rare neoplasm. Reports of new cases of peripheral desmoplastic ameloblastoma are necessary for a better understanding of the origin and behavior of this particular subtype of ameloblastoma.

Kaposi's sarcoma of the head and neck: a review.

Important advances in Kaposi's sarcoma (KS) knowledge have been achieved, but KS is still a dilemma. It is an angioproliferative disorder classified as an intermediate neoplasm due to the absence of conventional clinical features of malignancy, but at the moment, it remains unclear if KS could be considered a reactive proliferation of endothelial cells and spindle cells, a true malignancy or both. In this review, the authors address the main epidemiological, clinical, and biological features, of the five types of KS, with emphasis on KS affecting the head and neck region. Also, a revision is done in relation with transmission, the role of saliva, and the pathogenic events associated with human herpesvirus type-8 (HHV-8). Treatment options are revised, highlighting the need for future approaches focused on targeting signaling pathways.

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.

Analysis of p53 protein by PAb240, Ki-67 expression and human papillomavirus DNA detection in different types of odontogenic keratocyst.

OBJECTIVE: To investigate the possible association between alterations in the p53 system and human papillomavirus (HPV) infection in the etiology of odontogenic keratocysts (OKCs) and to study proliferation and epithelial maturation patterns by topographic analysis of Ki-67 expression. MATERIALS AND METHODS: Eighty-three OKC samples (29 cases associated with nevoid basal cell carcinoma syndrome, 29 solitary non-recurrent cases 20 solitary recurrent cases, and 5 chondroid keratocysts) were studied by immunohistochemistry to detect p53 protein (PAb 244) and Ki-67 (MIB-1) expression, and by PCR to detect HPV DNA. RESULTS: Twelve cases (14.6%) expressed p53 protein; no case showed the presence of HPV DNA; 9 cases (11%) presented with mild epithelial dysplasia. The suprabasal expression of Ki-67 was significantly more frequent than its basal expression (p < 0.001). p53 protein expression was significantly associated with the presence of epithelial dysplasia (p = 0.023). Ki-67 expression was not associated with OKC type, the presence of dysplasia, or p53 expression. CONCLUSION: HPVs do not participate in the etiology of OKC, and it appears unlikely that a p53 gene mutation mechanism plays a major role in the genesis of OKC. OKCs show proliferation and genuine maturation behavior reminiscent of benign neoplasms with local destructive capacity.

[Non-neoplastic enlargement of salivary glands: clinico-histologic analysis]. / Agrandamiento no neoplásico de glándulas salivales. Análisis clínico-histológico.

We carried out a retrospective study on non-neoplastic enlargement of the salivary glands at the Oral Histopathology Diagnostic Center of the Autonomous Metropolitan University at Xochimilco (UAM-Xochimilco) in Mexico during a period of 24 years (1979-2003). From 5,625 biopsies received and analyzed, a total of 461 (8.2%) were non-neoplastic enlargement of the salivary glands; for each case, we registered demographic data as well as clinic characteristics. These lesions were characterized as a heterogeneous group of pathologic entities among which we included local, obstructive, infectious, and immunopathologic lesions. The most frequent lesion was the extravasation cyst in 341 (74%) cases, followed by chronic sialoadenitis and Sjögren's syndrome with 54 (11.7%) and 41 (8.8%) cases, respectively, and at a lesser percentage mucous retention cyst, sialosis, benign lymphoepithelial lesions and those related with sialolytes. Females were affected more frequently; mean age was second to third life decades. These lesions were most frequently localized on inferior labial mucosa.