Adenomatoid odontogenic tumor: Features of ameloblastic-like epithelial cells differentiation, secretion, and the nature of tumor cells products.

BACKGROUND: This study aimed to investigate the differentiation of ameloblastic-like cells and the nature of the secreted eosinophilic materials in adenomatoid odontogenic tumors. METHODS: We studied histological and immunohistochemical characteristics of 20 cases using: cytokeratins 14 and 19, amelogenin, collagen I, laminin, vimentin, and CD34. RESULTS: Rosette cells differentiated into ameloblastic-like cells positioned face-to-face, displaying collagen I-positive material between them. Epithelial cells of the rosettes can differentiate into ameloblastic-like cells. This phenomenon probably occurs due to an induction phenomenon between these cells. The secretion of collagen I is probably a brief event. Amelogenin-positive areas were interspersed by epithelial cells in the lace-like areas, outside the rosettes and distant from the ameloblastic-like cells. CONCLUSIONS: There are at least two types of eosinophilic material in different areas within the tumor, one in the rosette and solid areas and another in lace-like areas. The secreted eosinophilic material in the rosettes and solid areas is probably a product of well-differentiated ameloblastic-like cells. It is positive for collagen I and negative for amelogenin, whereas some eosinophilic materials in the lace-like areas are positive for amelogenin. We hypothesize that the latter eosinophilic material could be a product of odontogenic cuboidal epithelial or intermediate stratum-like epithelial cells.

Oral melanomas in HIV-positive patients: Report of two cases and review of the literature.

Oral melanoma in HIV-positive patients is exceedingly rare, with only two cases reported in the literature published in English. Herein, we report two additional cases of oral melanomas which occurred as oral masses in the upper gingiva and hard palate in 35- and 27-year-old HIV-positive women. Significant thrombocytopenia, anemia, reduced CD4 cells, and high HIV load occurred in both patients. Microscopically, the lesions showed a variable proliferation of fusiform and epithelioid-pigmented cells, with cellular pleomorphism and high mitotic index. The diagnosis of melanoma was supported by positive immunoreactivity for S-100, MelanA, and HMB-45. Both cases had an unfavorable outcome, and the patients died a few months after the initial diagnosis. Because of its rarity, oral melanoma occurring in HIV-positive patients can pose problems in diagnosis and should be clinically distinguished from Kaposi's sarcoma, which is more common in the context of the immunodeficiency syndrome.