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El tumor odontogénico primordial (TOP) es un tumor odontogénico benigno mixto, descrito por primera vez en el 2014 por el Dr. Mosqueda Taylor y considerado como tal en la última clasificación de tumores de cabeza y cuello de la Organización Mundial de la Salud. Clínicamente se presenta como una lesión radiolúcida, bien definida, próxima a la corona de una pieza no erupcionada, pudiendo provocar expansión ósea, reabsorción radicular y desplazamiento de piezas vecinas. Presenta predilección por el sector posterior mandibular, el género masculino y en un rango etario de 2-19 años. Histopatológicamente presenta un tejido fibroso laxo con áreas similares a la papila dental, cubierto por un epitelio cuboide-columnar, que se asemeja al epitelio interno del órgano del esmalte, y se encuentra rodeado al menos parcialmente por una cápsula fibrosa. Objetivo: investigar la posible histogénesis y comportamiento biológico de TOP mediante el análisis inmunohistoquímico de sus componentes epitelial y mesenquimático, aplicando un amplio panel de anticuerpos. Materiales y métodos: se evaluaron 4 casos de TOP con un panel de 23 anticuerpos. Resultados. Las células epiteliales mostraron positividad en toda su extensión para citoqueratina 14 y 19, mientras que los anticuerpos amelogenina, glut-1, moc-31, caveolina-1, galectina-3, PITX2, p53, bax, bcl2, Survivina y PTEN presentaron positividad en áreas focales. El componente mesenquimático tumoral presentó positividad para vimentina, CD-138, PITX2, CD-105, CD-34, ciclina D1, bax, bcl-2, Survivina y p53. BRAFV600E y calretinina fueron negativos para todas las muestras. Los marcadores de proliferación celular Ki-67 y MCM-7 se expresaron en menos del 5% de las células tumorales. Conclusión: de acuerdo con los resultados inmunohistoquímicos podemos sugerir que TOP es un tumor que se desarrolla en las etapas inmaduras, o primordiales, de la odontogénesis, presentando zonas focales con diferentes grados de maduración y un bajo índice de proliferación celular.

Background: Myofibromas are rare benign neoplasms composed of myoid cells and myofibroblasts. This study aimed to systematically review case reports and a series of myofibromas (MF) and myofibromatosis (MFT) occurring in the oral and maxillofacial regions in order to describe their main clinicopathological features. Methods: This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses guidelines. Electronic searches were conducted in 2023 in four databases: MEDLINE/PubMed, Web of Science, Scopus, and EMBASE. A manual search and a search in the grey literature were also conducted. The lesions were classified as MF or MFT according to their original report. Results: A total of 169 cases were included in this systematic review. Men were slightly more affected, with a painless nodule. When occurring in soft tissue, MF usually developed in the gingiva (mean age:29.23 ± 21.93 years) and when it was intra‐osseous, it occurred more frequently in the posterior mandible (mean age:14.33 ± 15.62 years). MFT occurred mainly in the mandible and was predominantly described as well‐circumscribed masses of spindle cells organized in fascicles with a prominent vascular activity in a hemangiopericytoma‐like pattern. The lesions were mainly positive for smooth muscle actin and vimentin immunomarkers. Surgical excision was the treatment of choice in the majority of cases and recurrence was observed in only three cases. Conclusion: MF and MFT affect more men, with an indolent clinical course. Intra‐osseous tumors and MFT seem to occur more frequently in younger individuals. These lesions seem to have a good prognosis and low recurrence. [ABSTRACT FROM AUTHOR]

Actinic prurigo (AP) is a type of photodermatosis that primarily affects the Latin American mestizo population. Histologically, AP cheilitis exhibits acanthosis with spongiosis and vacuolation of the basal cell layer overlying a dense lymphocytic inflammatory infiltrate that forms well-defined lymphoid follicles. Toluidine blue is a thiazide, acidophilic, and metachromatic dye used in vivo to selectively stain the acidic components of tissues such as sulfates, carboxylates, and phosphate radicals that are incorporated into DNA and RNA. It is necessary to develop a method that allows detecting, on clinical grounds the area of the lesion in which it is more feasible to find such structures. Thus to increase the sensitivity of the biopsy, in AP cheilitis to accurately identify where the lymphoid follicles reside, based on the higher concentration of DNA in such structures and thus confirm the diagnosis. In this study, staining was positive in 85% of patients with AP cheilitis, in 14 of whom 82% lymphoid follicles were observed by histopathology. One of the pathologist’s problems in establishing the diagnosis of AP is that the main histopathological characteristics are not always identified in the submitted samples because it is not easy to clinically identify the most representative site of the lesion selected for performing a biopsy. Based on our results, we propose using toluidine blue as an auxiliary method to choose a tissue sample to facilitate the diagnosis and allow clinicians to make clinical correlations between the histopathological and therapeutic findings.

Todas las células de los mamíferos contienen un sistema citoplasmático de fbras esencial para la movilidad celular, el citoesqueleto, el cual se encuentra integrado por tres unidades estructurales principales y proteínas asociadas: microflamentos, microtúbulos y flamentos intermedios. Las citoqueratinas son flamentos intermedios que forman una red compleja que se extiende desde la superfcie del núcleo a la porción periférica de la célula, donde se insertan en desmosomas y hemidesmosomas. Las citoquerarinas 14 y 19 han sido utilizadas como marcadores de diagnóstico y pronóstico en diversas neoplasias de origen epitelial, no sólo permiten identifcar a una célula como epitelial, sino que permiten identifcar diferentes etapas durante diferenciación del epitelio y caracterizar el tumor. Existen numerosos trabajos en la literatura biomédica que han ejemplifcado la utilidad de citoqueratinas 14 y 19 para identifcar epitelio odontogénico. Esta revisión analiza la utilidad de su inmunoexpresión en los diferentes quistes y tumores odontogénicos.

This systematic review aimed to incorporate published information about synchronous odontogenic tumors (SOTs) with an analysis of the demographic and clinical characteristics from the cases published in the literature. Case reports and case series of SOT were searched in PubMed, Web of Science, Scopus, and EMBASE. A descriptive statistical analysis was performed. Twenty‐eight studies comprising 30 cases of SOTs were included. Considering all cases published, SOTs mostly occurred simultaneously in the maxilla and mandible (n = 19/63.3%). Lesions were bifocal in 13 (43.3% of all the 30 cases) and multifocal in 17 cases (56.7% of all the 30 cases). All SOTs available in the literature presented the same type of lesion, and two of them also involved another different SOT (n = 2/6.7% of all the 30 cases). Out of all published cases, the most frequent SOTs in the literature were odontomas (n = 10/33.3% of all the 30 cases), squamous odontogenic tumors (OTs) (n = 8/26.7% of all the 30 cases), calcifying epithelial OTs (n = 8/26.7% of all the 30 cases), and adenomatoid OTs (n = 2/6.7% of all the 30 cases). Considering all SOTs cases included, the overall recurrence was 13.3%. Inside a subgroup of the lesion, synchronous calcifying epithelial OT presented the highest (25%). Five cases (16.7% of all the 30 cases) had a previously associated syndrome, with two cases of Schimmelpenning syndrome being reported. Among published SOTs, odontomas were the most common. All SOTs available in the scientific literature showed the same type of OT and mainly affected both jaws simultaneously. Only a few of these cases were associated with a syndrome. [ABSTRACT FROM AUTHOR]

Background: Subgemmal neurogenous plaques (SNP) are composed of neural structures found in the posterolateral portion of the tongue, rarely biopsied as most of them are asymptomatic or eventually only clinically managed. We aimed to investigate a case series of possible correlation of symptomatic subgemmal neurogenous plaque (SNP) with coronavirus disease 2019 (COVID‐19). Methods: Eleven formalin‐fixed paraffin‐embedded cases from patients with previous confirmed COVID‐19 (by RT‐PCR) were retrieved from two pathology files. Histological sections were morphologically studied, and then submitted to immunohistochemical reactions against S‐100 and neurofilament proteins, neuron‐specific enolase, Glial fibrillary acidic protein (GFAP), synaptophysin, CD56, Ki67, cytokeratins (7, 8–18, 19, 20), nucleocapsid and spike proteins (SARS‐CoV‐1; and ‐2) and epithelial membrane antigen (EMA) antibodies. Clinical data were retrieved from the patients' medical files, including the symptoms and the complete history of the progression of the disease. Results: The patients who had COVID‐19 included in this study experienced painful lesions in the tongue that corresponded to prominent or altered SNP. Microscopically, neural structures were positive for S‐100, GFAP and neurofilament protein. And the cellular proliferative index (by Ki‐67) was very low. Conclusion: Thus, based on the current results, we hypothesize that symptomatic SNP may be a late manifestation of COVID‐19 infection. [ABSTRACT FROM AUTHOR]

Odontogenic tumors (OT) represent a specific pathological category that includes some lesions with unpredictable biological behavior. Although most of these lesions are benign, some, such as the ameloblastoma, exhibit local aggressiveness and high recurrence rates. The most common types of ameloblastoma are the solid/multicystic (SA) and the unicystic ameloblastoma (UA); the latter considered a much less aggressive entity as compared to the SA. The microRNA system regulates the expression of many human genes while its deregulation has been associated with neoplastic development. The aim of the current study was to determine the expression profiles of microRNAs present in the two most common types of ameloblastomas.MicroRNA expression profiles were assessed using TaqMan® Low Density Arrays (TLDAs) in 24 samples (8 SA, 8 UA and 8 control samples). The findings were validated using quantitative RTqPCR in an independent cohort of 19 SA, 8 UA and 19 dentigerous cysts as controls.We identified 40 microRNAs differentially regulated in ameloblastomas, which are related to neoplastic development and differentiation, and with the osteogenic process. Further validation of the top ranked microRNAs revealed significant differences in the expression of 6 of them in relation to UA, 7 in relation to SA and 1 (miR-489) that was related to both types.We identified a new microRNA signature for the ameloblastoma and for its main types, which may be useful to better understand the etiopathogenesis of this neoplasm. In addition, we identified a microRNA (miR-489) that is suggestive of differentiating among solid from unicystic ameloblastoma.

Background: Primordial odontogenic tumour is a benign mixed neoplasm of recent description, which has histological similarities with other odontogenic tumours such as the ameloblastic fibroma. In this article, we investigate the architecture of the sub‐epithelial layer of mesenchymal cells expressing the marker CD34 in primordial odontogenic tumour. Objective: Analyse the spatial patterns of CD34 expression in primordial odontogenic tumour and compare them with those in ameloblastic fibroma and the normal tooth germ by means of objective imaging approaches, to better characterise these lesions. Methods: Two cases of primordial odontogenic tumour, four cases of ameloblastic fibroma and two cases of tooth germ in cap and bell stages were used for morphological, structural and immunohistochemical analyses. Results: CD34 expression was found in vascular endothelium of primordial odontogenic tumour, ameloblastic fibroma and tooth germ. In addition, a characteristic sub‐epithelial expression was observed only in primordial odontogenic tumour, corresponding to 84%–86% of the sample boundaries. Moreover, the zone expressing CD34 corresponded with a higher cellularity, which was absent in ameloblastic fibroma and tooth germ. Conclusion: Image analysis of the primordial odontogenic tumour architecture revealed characteristics absent in other odontogenic tumours and tooth germs. This study provides additional information to support the idea that this neoplasm is a distinct entity from early stage AF or developing odontoma. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study is to present and discuss the salient clinicopathological features, differential diagnosis and epithelial immunohistochemical profile of three additional cases of peripheral odontogenic keratocyst (POKC) and to present a review of the literature. POKC is a locally aggressive odontogenic lesion. The peripheral variant of the odontogenic keratocyst is rare and more frequently located in anterior gingiva. Material and Methods: We present the clinicopathological features of 3 new cases of POKC (2 women and 1 man; age range: 14–74 years). Immunohistochemical study included CK7, CK14, CK19 and Ki‐67, and a systematic review of the literature was performed in PubMed, Scopus and Web of Science databases. Results: All cases were located in the anterior gingiva (2 in maxilla and 1 mandible), and none corresponded to Gorlin–Goltz syndrome. High expression of CK14 was seen in all cases, with CK19 and CK7 been only focally positive. The expression of Ki‐67 was located in the basal and parabasal cells in all cases. Conclusions: POKC is a rare gingival lesion that seems to originate from remnants of dental lamina or from the basal cells of the gingival epithelium and present a similar histopathology as compared to intraosseous OKC. [ABSTRACT FROM AUTHOR]

Background: Brown tumors are giant cell-rich lesions that result from abnormal bone metabolism in hyperparathyroidism, one of the most common endocrine disorders worldwide. Brown tumors occasionally affect the jaws and, despite well-known clinical and microscopic features, their molecular pathogenesis remains unclear. We investigated the presence of pathogenic activating mutations in TRPV4, FGFR1, and KRAS in a cohort of brown tumors since these have recently been reported in giant-cell lesions of the jaws and non-ossifying fibromas of the bones (FGFR1 and KRAS), which are histologic mimics of brown tumors.Methods: We target sequenced 13 brown tumors of the jaws associated with primary or secondary hyperparathyroidism. As mutations in these genes are known to activate the MAPK/ERK signaling pathway, we also assessed the immunostaining of the phosphorylated form of ERK1/2 (pERK1/2) in these lesions.Results: KRAS pathogenic mutations were detected in seven cases (p.G12V n = 4, p.G12D n = 1, p.G13D n = 1, p.A146T n = 1). KRAS variants of unknown significance (VUS), p.A134T and p.E37K, were also detected. All samples showed wild-type sequences for FGFR1 and TRPV4 genes. The activation of the MAPK/ERK signaling pathway was demonstrated by pERK1/2 immunohistochemical positivity of the brown tumors´ mononuclear cells.Conclusion: Mutations in KRAS and activation of the MAPK/ERK signaling pathway were detected in brown tumors of hyperparathyroidism of the jaws, expanding the spectrum of giant cell lesions whose molecular pathogenesis involve RAS signaling. [ABSTRACT FROM AUTHOR]

Background: Juvenile spongiotic gingival hyperplasia (JSGH) is a distinct clinicopathological entity of the buccal gingiva of young patients which has been related to several factors such as plaque formation, hormonal modifications, and viral infections; however, its true etiopathogenesis remains unsolved. Several immunohistochemical studies have demonstrated the similarity between the junctional epithelium (JE) and the hyperplasic epithelium of JSGH. The objective of this study is to analyze the clinicopathological and immunohistochemical characteristics of JSGH to explain its origin.Methods: Clinicopathlogical data of 10 cases of JSGH (five men and five women) with a mean age of 13 years (range: 9 to 17 years) were collected. CK7, CK14, CK19, CD3, CD20, S100, and Ki-67 antibodies were used for comparative immunohistochemical study.Results: All the lesions showed hyperplasic epithelium in its central portion, exhibiting marked spongiosis, vascular proliferation, and a chronic inflammatory infiltrate on the subepithelial connective tissue. CK19 was positive in the whole hyperplasic epithelium of JSGH and the basal layer of the marginal gingiva, while expression of CK14 was present in all epithelial layers of both the JSGH and that of the marginal gingiva. The subepithelial inflammatory infiltrate has a larger amount of CD20 positive cells.Conclusion: JSGH is a reactive tumor of the gingiva that may have an odontogenic etiology, whose origin seems to be the remnants of JE. [ABSTRACT FROM AUTHOR]