The aim of the study was to determine the distribution of histologically diagnosed nonodontogenic cysts (nOCs) over a 40-year period in a Brazilian population. Biopsy records from patients with nOC from the files of the Oral Pathology Service during the period of 1970-2009 were evaluated. Among 10,311 oral biopsies, 58 met the criteria of nOCs. The most frequent nOCs were nasopalatine duct cysts (32.8%), followed by epidermoid cysts (20.7%) and oral lymphoepithelial cysts (17.2%). Nasopalatine duct cysts showed predominance among females (68.4%). Epidermoid cysts were most commonly found in the floor of the mouth (36.4%), tongue (27.3%), and buccal mucosa (27.3%). Oral lymphoepithelial cysts exhibited female prevalence (80.0%) and were commonly located in the tongue (44.4%). The frequency of nOCs found in the population studied here is slightly different from those reported in other case series. Nasopalatine duct cysts, epidermoid cysts, and oral lymphoepithelial cysts were the most common nOCs found, accounting for 70.7% of all nOCs.

Adenomatoid odontogenic tumor (AOT) is an uncommon benign epithelial lesion of odontogenic origin and, thus far, only few studies regarding the frequency of its many histopathologic features have been published in the literature. Thus, the aim of this study was to perform a retrospective analysis in a case series of AOT, with emphasis on the histopathological features. Fifteen cases of AOT were studied considering their clinical, radiographic and histopathologic aspects. Twelve cases affected females and the mean age was 16.2 years. The anterior maxilla was the most common site (66.6 %) and radiographically most cases showed a unilocular radiolucency with well-defined borders (57.1 %). Histologically, most cases exhibited predominantly a solid growth pattern (46.7 %) or a similar proportion of solid and cribriform patterns (46.7 %). Eosinophilic amorphous material (''tumor droplets'') was found in all cases (100 %). Most tumors showed duct-like spaces (93.3 %) and convoluted structures (60.0 %) whereas a minor proportion of cases presented calcifying epithelial odontogenic tumor (CEOT)-like areas (26.7 %). Variable amounts of calcified material were found in most AOTs (80.0 %) whereas osteodentin and perivascular hyalinization were seen only rarely (6.7 % each one). Five (33.3 %) cases had areas mimicking a dentigerous cyst and most of these were diagnosed in females (80.0 %). Regarding the histopathologic features, our results suggest that AOTs usually show predominance of solid pattern or a similar proportion of solid and cribriform patterns while osteodentin and perivascular hyalinization are rarely seen in these tumors. In addition, areas mimicking a dentigerous cyst and CEOT-like areas are relatively infrequent findings in AOTs.

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MMP-9 and VEGF might play an important role in the osteoclastogenesis process in CGCL. The higher MVC in PGCL might be related to the reactive nature of these lesions.