Methyltransferase Inhibition Enables Tgfß Driven Induction of CDKN2A and B in Cancer Cells.

CDKN2A/B deletion or silencing is common across human cancer, reinforcing the general importance of bypassing its tumor suppression in cancer formation or progression. In rhabdomyosarcoma (RMS) and neuroblastoma, two common childhood cancers, the three CDKN2A/B transcripts are independently expressed to varying degrees, but one, ARF, is uniformly silenced. Although TGFß induces certain CDKN2A/B transcripts in HeLa cells, it was unable to do so in five tested RMS lines unless the cells were pretreated with a broadly acting methyltransferase inhibitor, DZNep, or one targeting EZH2. CDKN2A/B induction by TGFß correlated with de novo appearance of three H3K27Ac peaks within a 20 kb cis element ∼150 kb proximal to CDKN2A/B. Deleting that segment prevented their induction by TGFß but not a basal increase driven by methyltransferase inhibition alone. Expression of two CDKN2A/B transcripts was enhanced by dCas9/CRISPR activation targeting either the relevant promoter or the 20 kb cis elements, and this "precise" manipulation diminished RMS cell propagation in vitro. Our findings show crosstalk between methyltransferase inhibition and TGFß-dependent activation of a remote enhancer to reverse CDKN2A/B silencing. Though focused on CDKN2A/B here, such crosstalk may apply to other TGFß-responsive genes and perhaps govern this signaling protein's complex effects promoting or blocking cancer.

Mucoepidermoid carcinoma of the palate mimicking a pyogenic granuloma in a 30-year-old woman.

Mucoepidermoid carcinoma (MEC) is the most common salivary gland adenocarcinoma, more frequently affecting female patients in the fifth decade of life. When MEC arises in the minor salivary glands, the palate is the primary site. This case report describes an MEC on the palate of a 30-year-old woman. The lesion was initially treated as a pyogenic granuloma, but the final diagnosis based on histopathology was low-grade MEC. The patient was referred for cancer treatment, and no recurrence was observed during 3 years of follow-up. Some malignant tumors can mimic nonneoplastic reactive lesions clinically, which highlights the importance of biopsy and proper microscopic analysis of the resulting specimens.

Actinomycotic Osteomyelitis and Myiasis in Oroantral Communication: Clinicopathological and Tomographic Findings

Actinomycotic osteomyelitis of the maxilla presenting with oroantral communication is very rare, herein we report the first case of this condition in association with myiasis. A 50-year-old man reported chronic sinusopathy and a non-healing maxillary lesion, with 30 years of evolution, presenting occasional nasal and intraoral purulent discharge, with foul smell, and recurrent episodes of larvae presence. Cone beam computed tomography showed a large hyperdense image inside the left maxillary sinus, with focal areas with soft tissue density, and extensive discontinuity of the maxillary sinus floor, confirming the oroantral fistula. The necrotic tissue curetted during surgery presented hard consistency, and dark greenish color, and was submitted for histopathological analysis. Microscopically, necrotic bone, masses of filamentous bacteria colonie s, compatible with actinomycosis, and large rhomboidal structures surrounded by eosinophilic capsule - suggestive of larvae, were observed. The diagnosis of actinomycotic osteomyelitis with presence of structures compatible with larvae was established.

La osteomielitis actinomicótica del maxilar que se presenta con comunicación oroantral es poco frequente. En este trabajo reportamos el primer caso de esta condición en asociación con miasis. Un hombre de 50 años que refiere sinusopatía crónica y lesión maxilar que no cicatriza, de 30 años de evolución, presenta secreción ocasional purulenta nasal e intraoral, con mal olor y episodios recurrentes de presencia de larvas. La tomografía computarizada de haz cónico mostró una gran imagen hiperdensa en el interior del seno maxilar izquierdo, con áreas focales con densidad de partes blandas y una extensa discontinuidad del piso del seno maxilar, lo que confirma la fístula oroantral. El tejido necrótico legrado durante la cirugía presentó consistencia dura, coloración verdosa oscura, y fue remitido para análisis histopatológico. Microscópicamente se observó hueso necrótico, masas de colonias de bacterias filamentosas compatibles con actinomicosis y grandes estructuras romboidales rodeadas de cápsula eosinofílica sugestiva de larvas. Se estableció el diagnóstico de osteomielitis actinomicótica con presencia de estructuras compatibles con larvas.

Histomorphological evaluation, cell proliferation and endothelial immunostaining in oral and maxillofacial myofibroblastic lesions

Background: Myofibroblasts (MF) are mesenchymal cells with features of both fibroblasts and smooth muscle cells. Although these are usually reactive cells, they can lead to myofibroblastic tumors that may share clinical and histomorphological characteristics but with different prognosis. The aim of this study is to perform a histomorphological evaluation as well as to compare and evaluate two different cell proliferation immunomarkers and two endothelial markers in a group of oral and maxillofacial myofibroblastic lesions (MFL). Material and methods: Cross-sectional and retrospective study. Demographic, clinical, histomorphological and immunohistochemical characteristics of 39 cases of MFL were analyzed. Immunohistochemical reactions were performed with the Ki67, MCM2, CD34 and CD105 antibodies. Kruskal-Wallis test and Spearman correlation analysis were used. Results: Four cases of nodular fasciitis (NF), 18 myofibromas (My), 6 desmoplastic fibromas (DF), 7 inflammatory myofibroblastic tumors (IMT) and 4 myofibroblastic sarcomas (MFS) were studied. There were twenty women (51.2%); the median age was 13 [Q1-Q3: 8-24] years and most cases occurred in the mandible (48.7%). A statistically significant difference with MCM2 immunostaining (p=0.0221) was observed between the MFL; furthermore, a correlation between CD34 and CD105 immunostaining in NF (p <0.0001) and IMT (p=0.0408), between MCM2 and CD34 in IMT (p=0.0362) and between MCM2 and CD105 in MFS (p <0001) were found. Conclusions: MCM2 immunostaining could assess more clearly the cell growth fraction in MFL. The correlation between MCM2 and CD34 in IMT and between MCM2 and CD105 in MFS are indicative of the high activity of these lesions. These results emphasize the importance of the studied immunohistochemistry markers as possible tools for a better characterization of some of the MFL. (AU)

Oral epithelioid rhabdomyosarcoma: Report of a rare case and literature review of a distinct variant of rhabdomyosarcoma.

Epithelioid rhabdomyosarcoma is a new and rare morphological variant of rhabdomyosarcoma, with only a few reports in the literature. We aimed to describe an atypical case of this variant involving the oral cavity. A 33-year-old male patient presented with an asymptomatic, gingival mass adjacent to the left maxillary canine with progressive growth over approximately 3 months. Microscopic and immunohistochemical assessment of the biopsy specimen were consistent with epithelioid rhabdomyosarcoma. After initial chemotherapy and radiotherapy, the patient had a partial response. Surgical resection was performed, followed by adjuvant chemotherapy. After local and distant recurrences, the patient died 22 months after the initial diagnosis. According to the literature, epithelioid rhabdomyosarcoma still lacks data regarding its aetiologic factors and therapeutic options. Whether this tumour is a true subtype or simply a variant of other subtypes of rhabdomyosarcoma also remains unconfirmed. Final diagnosis leads to a broad array of microscopic and immunohistochemical analyses.

Acquired oral syphilis: A multicenter study of 339 patients from South America.

OBJECTIVE: To report the clinicopathologic features of acquired oral syphilis cases in South American countries. MATERIALS AND METHODS: Clinical data were retrospectively collected from the records of 18 oral diagnostic services in Argentina, Brazil, Chile, Colombia, Venezuela, Uruguay, and Peru. Serologies of nontreponemal and treponemal tests were used for diagnosis. RESULTS: The series comprised 339 cases of acquired oral syphilis. Secondary syphilis ranked as the most common stage (86.7%). Lesions were more frequent among males (58.0%) and young adults with a mean age of 33.3 years. Individuals aged 20-29 years were most affected (35.3%). The most commonly involved sites were the tongue (31.6%), lip/labial commissure (25.1%), and hard/soft palate (20.4%). Clinically, acquired oral syphilis usually presented as mucous patches (28.4%), papules (25.7%), and ulcers (18.1%). Skin manifestations occurred in 67.7% of individuals, while lymphadenopathy and fever were observed in 61.3% and 11.6% of all subjects, respectively. Most patients were treated with the benzathine penicillin G antibiotic. CONCLUSION: This report validates the spread of acquired oral syphilis infection among young adults in South America. Our directives include accessible diagnostic tools for proper disease screening, surveillance, and counselling of affected individuals, especially in low- and middle-income countries.

Baseline Power of Theta Oscillations Predicts Mystical-Type Experiences Induced by DMT in a Natural Setting.

N,N-Dimethyltryptamine (DMT) is a classic psychedelic capable of inducing short-lasting but profound changes in consciousness. As with other psychedelics, the experience induced by DMT strongly depends upon contextual factors, yet the neurobiological determinants of this variability remain unknown. The present study investigated changes in neural oscillations elicited by inhaled DMT, and whether baseline electroencephalography (EEG) recordings could predict the subjective effects reported by the participants. Healthy volunteers (N = 35) were measured with EEG before and during the acute effects of DMT consumed in a natural setting. Source-localized neural oscillations were correlated with the results of multiple questionnaires employed to assess the subjective effects of the drug. DMT resulted in a marked reduction of alpha and beta oscillations, and increased posterior spectral power in the delta, theta and gamma bands. The power of fronto-temporal theta oscillations was inversely correlated with scales indexing feelings of unity and transcendence, which are an integral part of the phenomenology of mystical-type experiences. The robustness of these results was supported using a machine learning model for regression trained and tested following a cross-validation procedure. These results are consistent with the observation that the state of mind prior to consuming a psychedelic drug influences the ensuing subjective experience of the user. They also suggest that baseline EEG screenings before administration of a serotonergic psychedelic could be useful to estimate the likelihood of inducing mystical-type experiences, previously linked to sustained positive effects in well-being and improved outcome of therapeutic interventions.

Comparison of orosomucoid-1 immunoexpression and angiogenesis between oral squamous cell carcinoma cases with different histological grades.

BACKGROUND: Oral squamous cell carcinoma (OSCC) is the most common malignancy in this region, and thus, further elucidation of its tumoral mechanisms is important. One of the main roles of the acute-phase protein orosomucoid-1 (ORM1) is the promotion of angiogenesis, which is key for tumor nutrition and growth. AIM: Our aim was to evaluate the immunohistochemical expression of ORM1 and the angiogenic activity indicated by microvascular density (MVD) in OSCC samples according to histological grade. MATERIALS AND METHODS: Formalin-fixed, paraffin-embedded sections from 45 OSCC cases were submitted to immunohistochemistry: 25 were well-differentiated OSCC, 18 were moderately differentiated OSCC and 2 were poorly differentiated OSCC. ORM1 staining was evaluated by a semiquantitative method, and CD34-positive blood vessels were quantified to calculate the MVD. The results were statically analyzed. RESULTS: All cases exhibited immunoexpression of ORM1 and CD34. However, no significant differences were found between the expression of both markers among the histological grades. In addition, the presence of ORM1 in inflammatory cells and in the extracellular matrix was detected in most cases. CONCLUSION: These results suggest that the induction of angiogenesis is not the main role of ORM1 in OSCC and may be associated with the regulation of the immune/inflammatory response or the transport of protumoral molecules, such as sialyl-Lewis X or phorbol esters, which requires confirmation in future studies.

Mature T/NK-Cell lymphomas of the oral and maxillofacial region: A multi-institutional collaborative study.

BACKGROUND: The diagnosis of oral and maxillofacial mature T/NK-cell neoplasms is challenging because of their rarity, morphological heterogeneity and complex immunophenotype with scarce available data describing their clinical and microscopic aspects. Therefore, in this study, we investigated a series of mature T/NK-cell neoplasms affecting this anatomical region and provided an updated literature review. METHODS: Cases diagnosed as mature T/NK-cell lymphomas affecting the oral and maxillofacial region were retrospectively retrieved from six pathology files and their diagnoses were confirmed using haematoxylin and eosin-stained slides, immunohistochemical reactions and in situ hybridization for Epstein-Barr virus (EBV) detection. Patients' clinical data were collected from their pathology forms. RESULTS: A total of 22 cases were included in this study. Eleven (50%) consisted of extranodal NK/T-cell lymphomas, nasal type; eight (36.4%) were peripheral T-cell lymphomas, NOS; two (9.1%) were adult T-cell leukaemia/lymphomas, and one (4.5%) was an ALK-positive anaplastic large cell lymphoma. Overall, males predominated, with a mean age of 55.7 years. The palate was the most affected site (50%), and tumours usually presented as destructive and painful ulcers. EBV was present in all cases of extranodal NK/T-cell lymphoma nasal type but was absent in the other subtypes. CONCLUSION: Among mature T/NK-cell lymphomas of the oral and maxillofacial region, extranodal NK/T-cell lymphoma, nasal type and peripheral T-cell lymphoma, NOS predominated. Older men were the most affected patients, and this heterogeneous group of neoplasms has a very aggressive clinical behaviour.

Kaposiform Hemangioendothelioma of the Oral Cavity: A Rare Tumor with an Unusual Location.

Kaposiform hemangioendothelioma is a rare neoplasm with intermediate malignant behavior, mainly affecting infants and children. Involvement head and neck is uncommon, and there are only four cases reported in the oral cavity and oropharynx. Microscopically, it is characterized by a vascular proliferation permeated by spindle-to-ovoid cells resembling Kaposi sarcoma. Immunohistochemically, the tumor is positive for CD31, CD34 and negative for D2-40. Herein we present a rare case of intraoral Kaposiform hemangioendothelioma in a 10-year-old boy.

Toward a New Era for the Management of Circulating Tumor Cells.

Circulating tumor cells (CTCs) are malignant cells separate from primary tumors, which can migrate through the peripheral blood, colonize other tissues, and lead to the formation of metastases. The first description of CTCs dates back to 1869 when Thomas Ashworth recognized malignant cells similar to the ones of the primary tumor in the blood vessels of an autopsied patient with metastatic cancer. Currently, CTCs have been identified in various types of cancer and have been recognized for their clinical value in the prediction of prognosis, diagnosis of minimal residual diseases, assessment of tumor sensitivity to anticancer drugs, and personalization of therapies. However, research about these topics has several limitations, principally the rarity of CTCs in bloodstream and their heterogeneous characteristics, which makes detection and isolation difficult. As a result of these limitations, current studies are focused on improvement of isolation and characterization techniques to achieve better sensitivity in clinical applications. This review covers the methods of CTC isolation and detection and current research progression on CTC in different cancer types. The clinical applications, limitations, and perspectives of CTCs are also discussed.

Perilipin 1 and adipophilin immunoexpression suggests the presence of lipid droplets in tooth germ, ameloblastoma, and ameloblastic carcinoma.

BACKGROUND: Increased lipogenesis and lipid droplet accumulation are observed in diverse tumors, and these processes are associated with poor prognosis in several tumors, representing potential therapeutic targets. The presence of lipid droplets in odontogenic tissues and/or tumors is unknown. METHODS: Immunohistochemistry for perilipin 1 and adipophilin was performed in 12 human tooth germs (TG), 27 conventional ameloblastoma (AM), and 8 ameloblastic carcinoma (AC) samples. Cytoplasmic staining was analyzed using an immunoreactive score (IRS), and the results were compared for the TG, AM, and AC samples by Kruskal-Wallis test followed by Dunn's post-test and confirmed by Mann-Whitney U test. RESULTS: Perilipin 1 was negative in 91.7% of the TG samples, positive in 48.2% of the AM samples, and positive in 87.5% of the AC samples. Adipophilin was positive in 100% of the TG samples, 92.6% of the AM samples, and 100% of the AC samples. The perilipin 1 and adipophilin IRS revealed statistically significant differences between the TG, AM, and AC samples (p = .007 and p = .018, respectively). The perilipin 1 levels among the TG and AC samples were statically significant (**p = .0085), as well as the adipophilin levels when TG and AM samples were compared (**p < .0029). CONCLUSIONS: Adipophilin exhibits significant activity in human tooth development. The immunoexpression of perilipin 1 and adipophilin in the AM and AC samples suggests the presence of lipid droplets, providing further evidence of metabolic alterations in these tumors. Additional studies with larger samples and alternative techniques are necessary to confirm these findings.

Expression of caveolin-1 in tooth germ, ameloblastoma and ameloblastic carcinoma / Expresión de caveolina-1 en germen dental ameloblastoma y carcinoma ameloblástico

Background: The caveolin-1 protein (structural component of membrane caveolae) plays important roles in sev-eral biological functions, such as endocytosis, cell adhesion, and cell signaling. However, this protein has been as-sociated with mechanisms of tumorigenesis in several neoplasms. The expression patterns and roles of caveolin-1in the oral epithelium and in embryonic and odontogenic tumor tissues are still unclear.Material and Methods: The expression of caveolin-1 was evaluated in samples of the normal gingival epithelium(n=7), human tooth germ (TG) (n=12), ameloblastoma (AM) (n=83), and ameloblastic carcinoma (AC) (n=9) byimmunohistochemistry. Additionally, AM samples were analyzed by qRT-PCR and Western blot.Results: Most TG (91.7%), AM (73.5%) and AC (100%) samples showed diverse patterns of immunohistochemicalpositivity for caveolin-1, while only one gingival sample was positive. The transcript levels of cav-1 were signifi-cantly upregulated by 14.9-fold in AM tissue (P = 0.0014) compared to those in normal gingival epithelial tissue,as shown by qRT-PCR. Presence of caveolin-1 protein was confirmed by Western blot analysis. The caveolin-1immunoexpression patterns throughout the stages of TG show its importance during odontogenesis.Conclusions: The overexpression of caveolin-1 in AM and AC compared to its expression in normal gingivalepithelium (adult tissue) suggests a possible role of caveolin-1 in protumoral events, but due to the similar immu-noexpression observed in AM and AC, caveolin-1 may not necessarily participate in the malignant transformationprocess. However, future studies are needed to clarify and confirm these hypotheses.(AU)

Neural and subjective effects of inhaled N,N-dimethyltryptamine in natural settings.

BACKGROUND: N,N-dimethyltryptamine is a short-acting psychedelic tryptamine found naturally in many plants and animals. Few studies to date have addressed the neural and psychological effects of N,N-dimethyltryptamine alone, either administered intravenously or inhaled in freebase form, and none have been conducted in natural settings. AIMS: Our primary aim was to study the acute effects of inhaled N,N-dimethyltryptamine in natural settings, focusing on questions tuned to the advantages of conducting field research, including the effects of contextual factors (i.e. "set" and "setting"), the possibility of studying a comparatively large number of subjects, and the relaxed mental state of participants consuming N,N-dimethyltryptamine in familiar and comfortable settings. METHODS: We combined state-of-the-art wireless electroencephalography with psychometric questionnaires to study the neural and subjective effects of naturalistic N,N-dimethyltryptamine use in 35 healthy and experienced participants. RESULTS: We observed that N,N-dimethyltryptamine significantly decreased the power of alpha (8-12 Hz) oscillations throughout all scalp locations, while simultaneously increasing power of delta (1-4 Hz) and gamma (30-40 Hz) oscillations. Gamma power increases correlated with subjective reports indicative of some features of mystical-type experiences. N,N-dimethyltryptamine also increased global synchrony and metastability in the gamma band while decreasing those measures in the alpha band. CONCLUSIONS: Our results are consistent with previous studies of psychedelic action in the human brain, while at the same time the results suggest potential electroencephalography markers of mystical-type experiences in natural settings, thus highlighting the importance of investigating these compounds in the contexts where they are naturally consumed.

Extranodal NK/T cell lymphoma, nasal type: An updated overview.

Extranodal NK/T-cell lymphoma, nasal type (ENKTCL-NT) is an aggressive malignancy associated with Epstein-Barr virus infection, with a geographic and racial predilection for some Asian and Latin American countries. ENKTCL-NT manifests as a necrotic process affecting nasal or upper aerodigestive structures and, rarely, extranasal sites such as skin, and the gastrointestinal tract. ENKTCL-NT was characterized by its poor prognosis irrespective of clinical stage and therapy. However, during the last two decades, advances in its clinicopathologic, genetic and molecular characterization have been achieved, as have changes in the chemotherapy regimens that, in combination with radiotherapy, are significantly improving the survival of these patients, especially in initial stages. For these reasons, we present an overview of the historical background of ENKTCL-NT along with an updated review of its potential etiological factors, clinicopathologic and molecular features, as well as its prognostic models, current treatment protocols, and future directions on potential promising therapeutic approaches.

BDNF/TrkB/Akt Signaling Pathway Epithelial Odontogenic Tumors and Keratocyst: An Immunohistochemical Study Comparative With Dental Germs.

Odontogenic lesions (OL) are an important group of oral and maxillofacial diseases represented by odontogenic cysts, benign, and malignant tumors. The brain-derived neurotrophic factor (BDNF)/ tropomyosin receptor kinase B (TrkB) signaling pathway has multiple biological actions and has been identified as an important pathway in the proliferation, invasion, and survival of different epithelial tumors. Its role in the development of OL, however, has so far been unexplored. Our aim was to evaluate the BDNF/TrkB/Akt/p-RPS6 signaling pathway in OL of epithelial origin. This cross-sectional study comprised 3 cases of tooth germs, 25 cases of odontogenic keratocyst (OK), 29 cases of ameloblastoma (Am), and 6 cases of ameloblastic carcinoma. Immunohistochemical staining for BDNF, TrkB, p-Akt, and p-RPS6 was performed. OLs were evaluated according to the pattern of immunohistochemical expression in epithelial cells and by semiquantitative scores that considered the intensity of staining and percentage of positive cells. BDNF stromal expression was also assessed. No significant differences were observed with respect to the percentage of positive cases for all markers. Regarding the immunoreactive scores, BDNF and p-RPS6 expressions were similar in the odontogenic epithelium of all OL. However, TrkB and p-Akt were overexpressed in OK compared with ameloblastic carcinoma. In Am, epithelial BDNF was significantly higher compared with stromal expression. In conclusion, BDNF seems to participate in the development of cystic, benign, and malignant odontogenic epithelium to similar degrees. The acquisition of the invasive or malignant phenotype in odontogenic neoplasms is not associated with alterations in the BDNF/TrkB/Akt/RPS6 axis, which could be implicated in the differentiation process.

Aggressive Intraosseous Myofibroma of the Maxilla: Report of a Rare Case and Literature Review.

Myofibroma (MF) is a benign mesenchymal myofibroblast-derived tumor, which occurs most frequently in children, and rarely affects the maxilla. We reported a case of an aggressive intraosseous lesion found in the maxilla of a 9-year-old female child. Intraorally, the swelling extended from tooth 12 to 16, causing displacement of teeth 13, 14, and 15. Computed tomography revealed a large osteolytic lesion causing thinning and cortical erosion. Microscopically, the lesion showed a proliferation of spindle-shaped cells, with elongated nuclei and eosinophilic cytoplasm, arranged in interlaced fascicles. The immunohistochemical analysis revealed cytoplasmic positivity for α-SMA and HHF-35, and negativity for desmin, laminin, S-100, ß-catenin, and CD34. Ki-67 was positive in 8% of tumor cells. The diagnosis was MF. Herein, we describe an additional case of central MF arising in the maxilla, including clinical, imaging, microscopical, and immunohistochemical features, as well as a review of the literature.

Mixed odontogenic tumors: A review of the clinicopathological and molecular features and changes in the WHO classification.

BACKGROUND: Ameloblastic fibromas and ameloblastic fibrosarcomas are rare odontogenic tumors, and controversy exists in the classification of cases presenting hard-tissue production: Ameloblastic fibrodentinoma (AFD) and ameloblastic fibro-odontoma (AFO). These cases are currently considered "developing odontomas" (hamartomatous lesions). AIM: To analyze the clinicopathologic features of these lesions and discuss the changes in the 2017 World Health Organization classification. METHODS: An electronic literature search was performed in the PubMed/MEDLINE database. An electronic search of the English language literature was performed and last updated in September 2020 in the PubMed/MEDLINE database using the following terms: "ameloblastic fibroma", "ameloblastic fibrodentinoma", "ameloblastic fibro-odontoma", "ameloblastic sarcoma", "ameloblastic fibrosarcoma", "ameloblastic fibrodentinosarcoma", "ameloblastic fibroodontosarcoma" and "odontogenic carcinosarcoma". The inclusion criteria were odontogenic tumor series, case reports and systematic reviews that provided sufficient clinical, radiological and microscopic documentation to confirm the diagnosis. RESULTS: The database search strategy resulted in 947 papers. Articles focusing on other topics, articles that were not in English, duplicate articles, and articles without fulfilling the inclusion criteria were excluded. Finally, 96 publications were included in this review to describe and discuss the main features of the searched entities. Several aspects of AFO and AFD, such as biological behavior, age of occurrence, amount of hard tissue, and potential for malignant transformation into odontogenic sarcomas, support the neoplastic nature in most of the reported cases. Considering the clinical, radiographic, histopathological and molecular characteristics of odontogenic lesions with hard tissue production, we suggest that these types of lesions should continue to be recognized as odontogenic tumors by maintaining the classically used terms. CONCLUSION: This recommendation will be relevant for future clinical, microscopic, and molecular studies to better understand the biology of these interesting odontogenic tumors.

Spindle cell carcinoma of the maxillary sinus with extension to the oral cavity.

Spindle cell carcinoma (SCC) is a rare variant of squamous cell carcinoma characterized by elongated and pleomorphic epithelial cells that resemble a sarcoma. Due to its rareness, and histological resemblance to various sarcomas, the diagnosis of this neoplasia is challenging. Herein we present the case of an 82-year-old female with a polypoid, ulcerated, soft tissue mass located on the left side of the maxilla. The tomographic examination showed a hyperdense mass that infiltrated the orbital cavity, ethmoidal cells, middle and lower nasal concha, maxillary sinus, zygomatic arch, and mandibular ramus on the left side. Histopathologically, the tumor was composed of spindle cells that were sarcomatous in appearance, with aberrant mitosis, along with a group of pleomorphic cells with a more epithelioid and hyperchromatic appearance on a stroma of densely vascularized fibrous tissue. The immunohistochemistry panel used to determine the lineage of the tumor rendered the diagnosis of SCC. The diagnosis of SCC is challenging to the pathologist since its morphology can resemble a sarcoma. Thus, immunohistochemistry is a valuable resource to support the diagnosis. We propose that SCC should be considered when examining a biphasic neoplasm with the aforementioned histological characteristics and markers.

Gingival squamous cell carcinoma mimicking a non-neoplastic proliferative lesion in an older patient.

OBJECTIVE: To report a case of gingival squamous cell carcinoma (SCC) in an elderly patient mimicking a non-neoplastic proliferative lesion. BACKGROUND: Oral SCC is a well-recognised malignancy of the oral cavity that may mimic benign reactive proliferative processes. METHODS: An excisional biopsy was performed, and the diagnosis was gingival SCC. CONCLUSION: It is essential that both the clinician and pathologist to be aware of such a presentation to allow for proper diagnosis and treatment.