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We describe a human lung disease caused by autosomal recessive, complete deficiency of the monocyte chemokine receptor C-C motif chemokine receptor 2 (CCR2). Nine children from five independent kindreds have pulmonary alveolar proteinosis (PAP), progressive polycystic lung disease, and recurrent infections, including bacillus Calmette Guérin (BCG) disease. The CCR2 variants are homozygous in six patients and compound heterozygous in three, and all are loss-of-expression and loss-of-function. They abolish CCR2-agonist chemokine C-C motif ligand 2 (CCL-2)-stimulated Ca2+ signaling in and migration of monocytic cells. All patients have high blood CCL-2 levels, providing a diagnostic test for screening children with unexplained lung or mycobacterial disease. Blood myeloid and lymphoid subsets and interferon (IFN)-γ- and granulocyte-macrophage colony-stimulating factor (GM-CSF)-mediated immunity are unaffected. CCR2-deficient monocytes and alveolar macrophage-like cells have normal gene expression profiles and functions. By contrast, alveolar macrophage counts are about half. Human complete CCR2 deficiency is a genetic etiology of PAP, polycystic lung disease, and recurrent infections caused by impaired CCL2-dependent monocyte migration to the lungs and infected tissues.
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Proteinose Alveolar Pulmonar , Receptores CCR2 , Criança , Humanos , Pulmão/metabolismo , Macrófagos Alveolares/metabolismo , Proteinose Alveolar Pulmonar/genética , Proteinose Alveolar Pulmonar/diagnóstico , Receptores CCR2/deficiência , Receptores CCR2/genética , Receptores CCR2/metabolismo , Reinfecção/metabolismoRESUMO
Needle-leaved junipers (Juniperus sect. Juniperus, Cupressaceae) are coniferous trees and shrubs with red or blue fleshy cones. They are distributed across Asia, Macaronesia and the Mediterranean Basin, with one species (J. communis) having a circumboreal distribution. Here we aim to resolve the phylogeny of this clade to infer its intricate evolutionary history. To do so, we built a comprehensive, time-calibrated phylogeny using genotyping-by-sequencing (GBS) and combine it with species occurrence using phylogeographic tools. Our results provide solid phylogenetic resolution to propose a new taxonomic classification and a biogeographical history of the section. Specifically, we confirm the monophyly of two groups within J. sect. Juniperus: the Asian (blue-cone) species including the circumboreal J. communis, and the Mediterranean-Macaronesian (red-cone) species. In addition, we provide strong phylogenetic evidence for three distinct species (J. badia, J. conferta, J. lutchuensis) previously considered subspecies or varieties, as well as for the differentiation between the eastern and western Mediterranean lineages of J. macrocarpa. Our findings suggest that the Mediterranean basin was the primary center of diversification for Juniperus sect. Juniperus, followed by an East Asian-Tethyan disjunction resulting from uplifts of the Qinghai-Tibetan Plateau and climatic shifts. The colonization history of Macaronesia by red-cone junipers from the western Mediterranean appears to have taken place independently in two different geological periods: the Miocene (Azores) and the Pliocene (Madeira-Canary Islands). Overall, genomic data and phylogenetic analysis are key to consider a new taxonomic proposal and reconstruct the biogeographical history of the iconic needle-leaved junipers across the Paleartic.
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Juniperus , Filogenia , Juniperus/genética , Juniperus/classificação , Filogeografia , Evolução Biológica , Análise de Sequência de DNARESUMO
BACKGROUND: Ameloblastoma and ameloblastic carcinoma are epithelial odontogenic tumors that can be morphologically similar. In the present study, we evaluated the DNA content and Ki-67 index in the two tumors. METHODS: The paraffin blocks of the tumors were selected to obtain sections for the immunohistochemical reactions and preparation of the cell suspension for acquisition in a flow cytometer. The Random Forest package of the R software was used to verify the contribution of each variable to classify lesions into ameloblastoma or ameloblastic carcinoma. RESULTS: Thirty-two ameloblastoma and five ameloblastic carcinoma were included in the study. In our sample, we did not find statistically significant differences in Ki-67 labeling rates. A higher fraction of cells in 2c (G1) was correlated with the diagnosis of ameloblastoma, whereas higher rates of 5c-exceeding rate (5cER) were correlated with ameloblastic carcinoma. The Random Forest model highlighted histopathological findings and parameters of DNA ploidy study as important features for distinguishing ameloblastoma from ameloblastic carcinoma. CONCLUSION: Our findings suggest that the parameters of the DNA ploidy study can be ancillary tools in the classification of ameloblastoma and ameloblastic carcinoma.
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Ameloblastoma , Carcinoma , Tumores Odontogênicos , Humanos , Ameloblastoma/diagnóstico , Ameloblastoma/genética , Ameloblastoma/patologia , Antígeno Ki-67/genética , Tumores Odontogênicos/genética , Carcinoma/patologia , Ploidias , DNARESUMO
BACKGROUND: Neural tumors are difficult to distinguish based solely on cellularity and often require immunohistochemical staining to aid in identifying the cell lineage. This article investigates the potential of a Convolutional Neural Network for the histopathological classification of the three most prevalent benign neural tumor types: neurofibroma, perineurioma, and schwannoma. METHODS: A model was developed, trained, and evaluated for classification using the ResNet-50 architecture, with a database of 30 whole-slide images stained in hematoxylin and eosin (106, 782 patches were generated from and divided among the training, validation, and testing subsets, with strategies to avoid data leakage). RESULTS: The model achieved an accuracy of 70% (64% normalized), and showed satisfactory results for differentiating two of the three classes, reaching approximately 97% and 77% as true positives for neurofibroma and schwannoma classes, respectively, and only 7% for perineurioma class. The AUROC curves for neurofibroma and schwannoma classes was 0.83%, and 0.74% for perineurioma. However, the specificity rate for the perineurioma class was greater (83%) than in the other two classes (neurofibroma with 61%, and schwannoma with 60%). CONCLUSION: This investigation demonstrated significant potential for proficient performance with a limitation regarding the perineurioma class (the limited feature variability observed contributed to a lower performance).
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Estudos de Viabilidade , Neoplasias Bucais , Neoplasias de Bainha Neural , Redes Neurais de Computação , Neurilemoma , Neurofibroma , Humanos , Neurofibroma/patologia , Neurilemoma/patologia , Neoplasias de Bainha Neural/patologia , Neoplasias Bucais/patologia , Diagnóstico DiferencialRESUMO
BACKGROUND: Amyloidosis exhibits a variable spectrum of systemic signs and oral manifestations that can be difficult to diagnose. This study aimed to characterize the clinical, demographic, and microscopic features of amyloidosis in the oral cavity. METHODS: This collaborative study involved three Brazilian oral pathology centers and described cases with a confirmed diagnosis of amyloidosis on available oral tissue biopsies. Clinical data were obtained from medical records. H&E, Congo-red, and immunohistochemically stained slides were analyzed. RESULTS: Twenty-six oral biopsies from 23 individuals (65.2% males; mean age: 59.6 years) were included. Oral involvement was the first sign of the disease in 67.0% of cases. Two patients had no clinical manifestation in the oral mucosa, although the histological analysis confirmed amyloid deposition. Amyloid deposits were distributed in perivascular (88.0%), periacinar and periductal (80.0%), perineurial (80.0%), endoneurial (33.3%), perimuscular (88.2%), intramuscular (94.1%), and subepithelial (35.3%) sites as well as around fat cells (100.0%). Mild/moderate inflammation was found in 65.4% of cases and 23.1% had giant cells. CONCLUSIONS: Amyloid deposits were consistently found in oral tissues, exhibiting distinct deposition patterns. Oral biopsy is less invasive than internal organ biopsy and enables the reliable identification of amyloid deposits even in the absence of oral manifestations. These findings corroborate the relevance of oral biopsy for the diagnosis of amyloidosis.
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Amiloidose , Placa Amiloide , Masculino , Humanos , Pessoa de Meia-Idade , Feminino , Amiloidose/diagnóstico , Amiloidose/patologia , Biópsia , Amiloide/análise , Boca/patologiaRESUMO
BACKGROUND: The purpose of this systematic review (SR) is to gather evidence on the use of machine learning (ML) models in the diagnosis of intraosseous lesions in gnathic bones and to analyze the reliability, impact, and usefulness of such models. This SR was performed in accordance with the PRISMA 2022 guidelines and was registered in the PROSPERO database (CRD42022379298). METHODS: The acronym PICOS was used to structure the inquiry-focused review question "Is Artificial Intelligence reliable for the diagnosis of intraosseous lesions in gnathic bones?" The literature search was conducted in various electronic databases, including PubMed, Embase, Scopus, Cochrane Library, Web of Science, Lilacs, IEEE Xplore, and Gray Literature (Google Scholar and ProQuest). Risk of bias assessment was performed using PROBAST, and the results were synthesized by considering the task and sampling strategy of the dataset. RESULTS: Twenty-six studies were included (21 146 radiographic images). Ameloblastomas, odontogenic keratocysts, dentigerous cysts, and periapical cysts were the most frequently investigated lesions. According to TRIPOD, most studies were classified as type 2 (randomly divided). The F1 score was presented in only 13 studies, which provided the metrics for 20 trials, with a mean of 0.71 (±0.25). CONCLUSION: There is no conclusive evidence to support the usefulness of ML-based models in the detection, segmentation, and classification of intraosseous lesions in gnathic bones for routine clinical application. The lack of detail about data sampling, the lack of a comprehensive set of metrics for training and validation, and the absence of external testing limit experiments and hinder proper evaluation of model performance.
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Inteligência Artificial , Radiômica , Humanos , Ameloblastoma/diagnóstico por imagem , Ameloblastoma/patologia , Cisto Dentígero/diagnóstico por imagem , Doenças Maxilomandibulares/diagnóstico por imagem , Aprendizado de Máquina , Cistos Odontogênicos/diagnóstico por imagem , Cistos Odontogênicos/patologia , Reprodutibilidade dos TestesRESUMO
Cellular neurothekeoma (CN) is a benign dermal neoplasm that most often affects the head and neck region and rarely occurs in the oral mucosa. We report a rare case of CN with atypical features on the floor of the mouth and summarize the reported cases of oral CN in English-language literature. A 62-year-old woman presented with a 6-month history of a painless mass on the floor of the mouth. Histopathological analysis of the excised specimen revealed a proliferation of neoplastic cells with oval to spindle morphology arranged in a vaguely nested and multinodular architecture separated by scarce hyaline collagen within a predominantly myxoid-rich stroma. The tumor cells were positive for NSE, and CD63 (NKI/C3), and negative for S100 protein, CD34, and SMA. Thus, the final diagnosis was CN. In addition, we summarized all clinicopathological data on oral CNs reported in the English-language literature. Nineteen cases were reviewed. Among them, only one case affected the floor of the mouth of a young girl, in contrast to the present case that occurred in an elderly woman. CN is particularly rare in this location and may be a diagnostic challenge for oral pathologists due to its rarity and morphological similarity with other lesions.
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OBJECTIVE: Histopathological grading of oral epithelial dysplasia (OED) is the current standard for stratifying cancer progression risk but is associated with subjectivity and variability. This problem is not commonly seen regarding the grading of epithelial dysplasia in other sites. This systematic review aims to compare grading systems for oral, anal, penile, and cervical epithelial dysplasia to determine their predictive accuracy for recurrence and malignant transformation (MT) outcomes. METHODS: The review protocol was registered in PROSPERO (CRD42023403035) and was reported according to the PRISMA checklist. A comprehensive search was performed in the main databases and gray literature. The risk of bias in individual studies was analyzed using the Joanna Briggs Institute checklist for each study design. RESULTS: Forty-six studies were deemed eligible and included in this systematic review, of which 45 were included in the quantitative analysis. Meta-analysis revealed that the binary system demonstrated a higher predictive ability for MT/recurrence of OED compared to multilevel systems. Higher predictive accuracy of MT was also observed for binary grading systems in anal intraepithelial neoplasia. CONCLUSIONS: No significant difference was found between the current grading systems of epithelial dysplasia in different body parts. However, binary grading systems have shown better clinical outcomes.
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OBJECTIVES: To conduct a comprehensive proteomic analysis of normal salivary gland tissue, pleomorphic adenoma (PA), and carcinoma ex-pleomorphic adenoma (CXPA), and validate the proteomic findings using immunohistochemistry. METHODS: Six normal salivary gland tissues, seven PA and seven CXPA samples underwent laser microdissection followed by liquid chromatography coupled to mass spectrometry. Protein identification and quantification were performed using MaxQuant software. Statistical analysis and functional enrichment were conducted using the Perseus platform and STRING tool, respectively. Immunohistochemistry was used for validation. RESULTS: Comparative proteomic analysis revealed 2680 proteins across the three tissue types, with 799 significantly altered between groups. Translocation protein SEC63 homolog, Annexin A6 and Biglycan were up-regulated in CXPA compared to PA. Decorin was markedly up-regulated in both PA and CXPA compared to normal salivary gland (log2 fold changes of 7.58 and 7.38, respectively). Validation confirmed elevated levels of Biglycan and Decorin in the extracellular matrix of CXPA compared to PA. CONCLUSIONS: Proteomic analysis identified differential protein expression patterns associated with malignant transformation of PA into CXPA. Findings indicate a crucial role for extracellular matrix proteins, specifically Biglycan and Decorin, in the tumorigenic progression of PA and CXPA.
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This article aims to explore the integration of ChatGPT, an advanced conversational artificial intelligence model, in the field of dentistry. The review primarily consists of information related to the capabilities and functionalities of ChatGPT and how these abilities can aid dental professionals. This study includes data from research papers, case studies, and relevant literature on language models, as well as papers on dentistry, patient communication, dental education, and clinical decision-making. A systematic approach was used to select relevant studies and literature. The selection criteria focused on papers that specifically discussed the integration of language models, ChatGPT in particular, in dentistry and their applications. The study findings revealed that ChatGPT has significant potential to revolutionize dentistry by offering various applications and benefits. It can enhance patient engagement and understanding through personalized oral health information and guidance. In dental education, ChatGPT can provide interactive learning, case studies, and virtual patient simulations. ChatGPT can also assist researchers in analyzing dental literature, identifying patterns, and generating insights. Moreover, it supports dentists with evidence-based recommendations, treatment options, and diagnostic support. Integrating ChatGPT in dentistry can be highly beneficial, but it is crucial to address ethical considerations, accuracy, and privacy concerns. Responsible implementation and continuous improvement of its functionalities are necessary to ensure that patient care and outcomes are improved.
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Inteligência Artificial , Humanos , Odontologia/tendências , Comunicação , Educação em Odontologia/tendênciasRESUMO
BACKGROUND AND OBJECTIVE: Detailed finite element models based on medical images (µ-CT) are commonly used to analyze the mechanical behavior of bone at microscale. In order to simulate the tissue failure onset, isotropic failure criteria of lamellar tissue are often used, despite its non-isotropic and heterogeneous nature. The main goal of the present work is to estimate the in-plane ultimate stress of lamellar bone, considering the influence of mineral content and the porosity due to the osteocyte lacunae concentration. METHODS: To this aim, a representative volume cell of lamellar tissue is modeled numerically, including: (1) non-isotropic elastic properties of tissue as a function of the bone mineral density and (2) explicit modeling of the osteocyte lacunae, considering the range of porosity content, size and orientation of ellipsoid-shaped lacunae. Firstly, the element size for the finite element models have been defined from a preliminary convergence analysis. Bounds on the ultimate stress of non-porous lamellar tissue are estimated for two values of bone mineral density, considering the results of tensile and compressive tests of wet osteons from the literature. Subsequently, the ultimate stress of lamellar tissue considering several values of micro-porosity is addressed. RESULTS: Results obtained in this work show that the strength of lamellar bone decreases exponentially with the increase of lacunae porosity concentration. Ultimate stress of non-porous tissue (p=0%) increases with high mineral content, reaching a value of S¯transc=355.40±39.80 MPa for compression in the transversal direction of the fiber bundles, being BMD=1.246g/cm3. The mean value for the longitudinal to transverse strength ratio evaluated for porosity p=0%,1% and 5% and a mineral content BMD=1.2g/cm3, is 2.47:1 for tension and 1.55:1 for compression. These values are in agreement with literature. CONCLUSIONS: Osteocyte lacunae act as stress concentrators, acting as potential stimulus for the bone regeneration process. A novel micromechanical model for the in-plane ultimate stress of lamellar tissue as a function of mineral content and lacunae concentration is presented. Additional considerations about the intralamellar shear stress evolution are also given.
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Densidade Óssea , Osteócitos , Porosidade , Osso e Ossos/diagnóstico por imagem , MineraisRESUMO
Background: Shoulder pain is one of the most important musculoskeletal conditions affecting the upper extremities. Glenohumeral osteoarthritis (GHOA) and rotator cuff injuries (RCIs) are notable for their high prevalence. The critical shoulder angle (CSA) is a significant radiological measure for determining the diagnosis and progression of patients with these conditions. Although there are reports in the international literature about this measure, in our country, guideline values considering these two pathologies are unknown. Objective: Our objective was to assess patients diagnosed with GHOA and RCI using an AP X-ray view and the CSA. Methods: To conduct this, we identified differences between sexes and age categories. Fifty-nine adult patients with GHOA and RCI were included. CSA grades varied depending on the age category and type of injury evaluated. Results: Significant differences between the age ranges of 40 and 54 (p = 0.05), 55-69 (p = 0.001), and 70-84 (p = 0.017) were observed. Conclusions: Patients with RCI tended to be younger and have a higher CSA compared to those with GHOA. It is important to have more normative values and to continue monitoring the critical shoulder angle in these patients.
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Astydamia latifolia is the only species of the genus Astydamia, which forms an early-diverging lineage of Apiaceae, subfamily Apioideae. This species is subendemic to the Canary Islands and one of the most representative species of the coastal environments of this archipelago. Astydamia displays diplochory, that is, diaspores with two long-distance dispersal (LDD) syndromes. In particular, A. latifolia has both anemochorous and thalassochorous fruit traits (corky and winged mericarps). Although we expect this species to have a high dispersal capacity, there is no genetic study addressing it. The divergence time of this species from its sister taxon is also unknown. In this study, we aimed (i) to unveil the phylogenetic relationships and divergence times of A. latifolia; (ii) to reconstruct its phylogeographic structure across the Canary Islands; and (iii) to estimate the number of inter-island colonization events. To these ends, we first sequenced the internal transcribed spacer (ITS) region for A. latifolia, reconstructed the phylogenetic relationships of Astydamia and Apiaceae relatives and estimated divergence times. Then, two plastid DNA regions (psaI-aacD and psbK-trnS) were sequenced for 158 individuals (from 36 Canarian population and one NW African population) to reconstruct a haplotype network. The recently developed method Phylogeographic Analysis of Island Colonization Events (PAICE) was used to estimate the number of inter-island colonization events. Results show that A. latifolia is a phylogenetically isolated lineage that diverged from the most closely related genus (Molopospermum) in the Eocene-Miocene. It displays a low plastid DNA diversity (only four haplotypes detected), which is accompanied by a high degree of haplotype sharing between islands and highly linear rarefaction curves of colonization obtained in PAICE. These findings suggest a high colonization ability for this species, most likely related to the availability of two LDD syndromes.
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Ectomesenchymal chondromyxoid tumor (ECT) is a rare soft tissue tumor with peculiar histogenesis, exhibiting a predilection for the dorsum of the tongue. Molecular evidence suggests that it may originate from the migration of ectomesenchymal pluripotent cells from the neural crest to the tongue, where these cells may eventually proliferate and undergo myxoid and chondroid differentiation. This article illustrates a case of a 16-year-old female patient who presented with a nodule on the dorsum of her tongue, which had been present for four years. Surgical excision was performed, and histopathological analysis revealed a myxoid neoplasia composed of polygonal and spindle cells within a loose stroma containing chondroid areas. Tumor cells were positive for GFAP and S-100 proteins on immunohistochemical study, confirming the diagnosis of ECT. After a 5-year follow-up, the patient has shown no evidence of recurrence. Although rare, ECT can be diagnosed straightforwardly due to its distinctive clinical, histopathological, and immunohistochemical features. Clinicians and pathologists should become familiar with this tumor in order to avoid misdiagnosis.
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Neoplasias da Língua , Humanos , Feminino , Neoplasias da Língua/patologia , Adolescente , Mesenquimoma/patologia , Mesenquimoma/diagnóstico , Biomarcadores Tumorais/análiseRESUMO
BACKGROUND: Salivary gland cystadenoma (SGCA) is a rare benign tumor that predominantly occurs in the parotid gland. SGCAs affecting the minor salivary glands are uncommon and often resemble, clinically and histopathologically, other salivary gland lesions. METHODS: This study aimed to describe a series of four cases of SGCA affecting intraoral sites and performed a literature review of well-reported SGCA published in the English-language literature. RESULTS: SGCA cases included in this series were diagnosed in the buccal mucosa, lip, and hard palate of female patients aged between 19 and 78 years. All cases underwent excisional biopsy and were histologically characterized by a multicystic growth with variable degrees of capsule formation and were lined by several types of epithelium, including some cell types that are infrequently reported in SGCA. In some cases, a small collection of lymphocytes was observed adjacent to cystic formations. All SGCA were positive for periodic acid-Schiff, and immunohistochemical reactions were positive for CK7 and p63. The follow-up time ranged widely from 3 to 53 months, and to date, no recurrence has been observed. CONCLUSION: The literature review revealed a total of 33 published studies accounting for 55 SGCA cases.
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Cistadenoma , Neoplasias das Glândulas Salivares , Humanos , Feminino , Neoplasias das Glândulas Salivares/patologia , Adulto , Pessoa de Meia-Idade , Cistadenoma/patologia , Idoso , Adulto JovemRESUMO
Objective: It is necessary to establish the evolution that the pandemic has had in Panama by weeks and months and to clearly establish the existence of surges or peaks, according to cases and deaths and the relationship with age groups. Methodology: We conducted a retrospective cohort study of all confirmed COVID-19 cases reported by the Ministry of Health of Panama during the first 3 years of the epidemic (March 9, 2020, March 11, 2023). All cases were obtained from information provided by the Ministry of Health. We obtained daily information of the population at the national level reported as new cases, deaths, admission to hospitals, admission to intensive care units and by age groups. The information is classified by epidemiological week and by month from the diagnosis of the first case until March 2023. Results: During the three years of the study, 1,032,316 cases of COVID-19 were registered in the Republic of Panama, and the number of deaths reported was 8,621, for a fatality rate of 0.83 % throughout that period. The number of deaths decreased over the 3 years of the pandemic; however, similar to the cases, there were periods of surges (peaks) per year in June/July and in December/January. The lethality progressively increased according to the age of the affected patients. During the first year, the lethality in those under 20 years of age was 0.05 %, and in those over 80 years old, it was 17.54 %. This pattern was maintained during the second year; however, there was a large decrease in all age groups. Conclusion: the highest lethality rate in Panama occurred in the first year of the pandemic, with a great decrease in the third year; the impact of lethality is proportional to the age of the individual, with a high possibility of death in those over 80 years of age. During each pandemic year, there are two peaks (surges of new cases and deaths) per year, which are important times to take into account to generate strategies aimed at reducing the impact.
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OBJECTIVE: Sirolimus (SRL) and everolimus (EVL) are increasingly included in immunosuppressive protocols after heart transplantation. They present some side effects, including the appearance of painful lesions in the oral cavity. Therefore, this systematic review aimed to verify the global prevalence and clinical characteristics of oral lesions induced by SRL and EVL in heart transplant patients. STUDY DESIGN: A systematic review was performed using 5 main electronic databases (Medline/PubMed, SCOPUS, EMBASE, Web of Science, and LILACS), in addition to the gray literature. Studies were independently assessed by 2 reviewers based on established eligibility criteria. The risk of bias was assessed using the Joanna Briggs Institute appraisal tools, and the certainty of evidence was evaluated through GRADE assessment. RESULTS: Seventeen studies (860 patients) were included in the qualitative analysis. Of these, 11 studies were pooled in a meta-analysis of prevalence. The worldwide prevalence of oral lesions induced by SRL and EVL in heart transplant patients was 10.0%, and most lesions were described as ulcers >1.0 cm, related to significant pain. CONCLUSIONS: Oral lesions induced by SRL and/or EVL, although not very prevalent, have a relevant impact on patient's lives and the continuity of treatment.
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Everolimo , Transplante de Coração , Humanos , Everolimo/efeitos adversos , Sirolimo/efeitos adversos , Prevalência , Imunossupressores/efeitos adversos , Transplante de Coração/efeitos adversosRESUMO
PURPOSE: This study describes a large, well-documented case series of salivary gland polymorphous adenocarcinomas (PAC) from a single Brazilian center. METHODS: Demographic data, clinical presentation, histopathological and immunohistochemical features from 26 cases of PAC were analyzed and discussed in detail. RESULTS: Most patients were females (n = 21), with a ratio of 1:4.2 (male: female) with a mean age of 58.8 years (ranging from 36 to 84 years). The most common clinical presentation was a fibrocollagenous, firm nodular lesion, with a mean size of 2.46 cm (ranging from 0.5 to 3 cm). Most lesions occurred on the palate (n = 16), followed by buccal mucosa (n = 3), upper lip (n = 3), buccal vestibule (n = 2) and alveolar ridge (n = 1). Histologically, various growth patterns were observed, including tubular, solid, cribriform, papillary, and cystic. Additionally, glomeruloid slit-like structures, mucous, and clear cells were noted. Surface papillary epithelial hyperplasia was observed in a few cases. Nine cases exhibited myxoid and collagenous areas, while two cases showed fusiform areas and another case demonstrated squamous differentiation. Clear cell predominance was noted in two cases, and peri- and intraneural invasion was seen in eight cases. Immunohistochemical analysis revealed positivity for S-100, p63 and CK7, and negativity for p40 in all cases. The Ki-67 proliferation index was markedly low in most cases, with a mean of 2.5%. CONCLUSION: We have provided a broad, detailed description of the clinical and microscopic features of PAC in a large, Brazilian cohort. These findings, in a resource-limited area, may be quite useful for establishing a proper diagnosis.