Cheilitis Glandularis: A clinicopathologic study with emphasis on etiopathogenesis.

OBJECTIVES: Cheilitis Glandularis (CG) is an uncommon entity of obscure etiology. A cases series is presented with emphasis on etiopathogenesis. MATERIALS AND METHODS: Fourteen CG cases were analyzed according to their demographic and clinicopathologic characteristics. RESULTS: The mean age of the patients with CG was 68.1 years, while a male-to-female ratio of 1.8:1 was observed. One or more potential causative factors were identified for each patient, including long-term smoking (9 cases), xerostomia (4 cases), cosmetic filler injections (2 cases), and actinic cheilitis (1 case). The lesions were located on the lips, buccal mucosa, or both in 7, 2, and 5 cases, respectively. Multiple submucosal nodules with dilated ductal orifices and mucous or purulent discharge were observed in all cases. Histopathologically, ductal ectasia with metaplasia, intraductal mucin, and chronic or mixed inflammation were noted, as well as pools of hyaluronic acid in 2 cases with a history of cosmetic filler injections. CONCLUSIONS: CG etiopathogenesis is probably multifactorial. Reduced salivary flow rate and increased viscosity of saliva, potentially caused by long-term smoking, diabetes mellitus, and drug-induced xerostomia, may participate in the initial pathogenesis, while local irritants, for example, poor oral hygiene and local trauma, may further contribute to the development and aggravation of the condition.

Management of oral herpes simplex virus infections: The problem of resistance. A narrative review.

Herpes Simplex Virus (HSV) type 1 (HSV-1) and type 2 (HSV-2) are among the most common human viral pathogens, affecting several billion people worldwide. Although in healthy patients clinical signs and symptoms of HSV infection are usually mild and self-limiting, HSV-infections in immunocompromised patients are frequently more aggressive, persistent, and even life-threatening. Acyclovir and its derivatives are the gold standard antiviral drugs for the prevention and treatment of HSV infections. Although the development of acyclovir resistance is a rather uncommon condition, it may be associated with serious complications, especially in immunocompromised patients. In this review, we aim to address the problem of drug resistant HSV infection and discuss the available alternative therapeutic interventions. All relative studies concerning alternative treatment modalities of acyclovir resistant HSV infection published in PubMed between 1989 to 2022 were reviewed. Long-term treatment and prophylaxis with antiviral agents predisposes to drug resistance, especially in immunocompromised patients. Cidofovir and foscarnet could serve as alternative treatments in these cases. Although rare, acyclovir resistance may be associated with severe complications. Hopefully, in the future, novel antiviral drugs and vaccines will be available in order to avoid the existing drug resistance.

Prognostic outcomes of oral squamous cell carcinoma derived from proliferative verrucous leukoplakia: A systematic review.

OBJECTIVE: This study aimed to evaluate prognostic outcomes of PVL-derived oral squamous cell carcinomas (P-OSCC) based on recurrence, new primary tumour, metastasis and survival information. STUDY DESIGN: Five databases and grey literature were searched electronically with the following main keywords (proliferative verrucous leukoplakia, squamous cell carcinoma and malignant transformation) to answer the following review question: 'Are survival outcomes for P-OSCC worse?' based on the PECOS principle. The Joanna Briggs Institute Critical Appraisal tool was used to identify possible biases and assess the quality of each of the primary studies. RESULTS: A total of 21 articles met the inclusion criteria, and the results of this systematic review suggest that P-OSCC can recur and generate new primary tumours; however, metastases are rare. Thus, most patients remain alive for an average period of 5 years. CONCLUSION: Apparently, P-OSCC has better clinical prognostic characteristics than conventional OSCC. There is a lack of information on the main prognostic outcomes of P-OSCC; therefore, specific studies must be performed to achieve a better comparison between P-OSCC and conventional OSCC progression.

The oral mycobiome: Oral epithelial dysplasia and oral squamous cell carcinoma.

Fungi, a diverse group of eukaryotic organisms, play distinct roles in health and disease. Recent advances in the field of mycobiology have enabled the characterization of the "human mycobiome." The human mycobiome has extensively been studied in various disease models. However, to date, the role of the oral mycobiome in oral carcinogenesis has yet to be elucidated. Candida albicans, the most common oral colonizer, has been speculated to display tumorigenic effects; however, the literature lacks consistent documentation from mechanistic studies on whether oral mycobiota act as drivers, facilitators, or passive colonizers of oral premalignancy and cancer. This review article provides an overview of existing hypothesis-driven mechanistic models that outline the complex interplay between the oral mycobiome and oral epithelial dysplasia as well as their potential clinical implications.

The role of M1 and M2 macrophage polarization in progression of medication-related osteonecrosis of the jaw.

OBJECTIVES: The aim of this study was to investigate the relationship between M1 and M2 macrophage polarization and clinical stage in patients with medication-related osteonecrosis of the jaw (MRONJ) who underwent treatment with bisphosphonates or denosumab. MATERIALS AND METHODS: M1 and M2 macrophage density and expression of interleukin (IL)-6 and IL-10 were assessed on biopsies of mucosal tissues surrounding necrotic bone in 30 MRONJ patients with stages 1-3 and controls. For identification of M1 and M2 macrophages, double CD68/iNOS and CD68/CD206 immunofluorescence staining was conducted, respectively. Computer-assisted immunofluorescence quantification of markers was performed. RESULTS: Early stage 1 MRONJ patients showed a switch toward the M2 phenotype, as indicated by the higher density of M2 macrophages, the decreased M1/M2 ratio, and the upregulation of IL-10. MRONJ patients with advanced stages 2 and 3 showed a shift toward M1-polarized macrophages, as suggested by the higher density of M1 macrophages, the increased M1/M2 ratio, and the overexpression of IL-6. The macrophage density of both M1 and M2 subsets was significantly enhanced in patients receiving bisphosphonates compared with those receiving denosumab. CONCLUSIONS: The M1-M2 macrophage polarization status in mucosal tissues bordering necrotic bone correlates with clinical stage of MRONJ. Patients with early-stage MRONJ show a switch toward M2-polarized macrophages, while MRONJ patients with advanced stage demonstrate a shift toward the M1 phenotype. CLINICAL RELEVANCE: Therapeutic molecules targeting the inflammatory microenvironment via the regulation of either M1 or M2 macrophage polarization may represent a novel strategy for treatment of MRONJ.

Denosumab-related osteonecrosis of the jaw: a report of 2 cases and review of the literature.

Bisphosphonates have been implicated in the induction of medication-related osteonecrosis of the jaw (MRONJ) since 2004. Since then, the spectrum of drugs implicated in the onset of MRONJ has broadened to include other antiresorptive and antiangiogenic drugs. Denosumab is an antiresorptive drug that has been on the market since 2010. Denosumab inhibits osteoclast formation, function, and survival and increases bone mineral density. As a result, denosumab is indicated for the treatment of osteoporosis and bone metastases. This article reports 2 cases of MRONJ associated with denosumab use. The characteristics and progression of MRONJ in patients who take denosumab are reviewed, and therapeutic measures are discussed.

DSPP-MMP20 gene silencing downregulates cancer stem cell markers in human oral cancer cells.

BACKGROUND: Recent findings indicate that dentin sialophosphoprotein (DSPP) and matrix metalloproteinase (MMP) 20 interact in oral squamous cell carcinoma (OSCC). The objective of this study was to determine the effects of DSPP/MMP20 gene silencing on oral cancer stem cell (OCSC) markers. METHODS: The expression of well-established OCSC markers: ABCG2; ALDH1; CD133; CD44; BMI1; LGR4, and Podoplanin in DSPP/MMP20-silenced OSCC cell line, OSC2, and controls were assayed by western blot (WB), and flow cytometry techniques. The sensitivity of OSC2 cells to cisplatin following DSPP/MMP20 silencing was also determined. RESULTS: DSPP/MMP20 silencing resulted in downregulation of OCSC markers, more profoundly ABCG2 (84%) and CD44 (81%), following double silencing. Furthermore, while treatment of parent (pre-silenced) OSC2 cells with cisplatin resulted in upregulation of OCSC markers, DSPP/MMP20-silenced OSC2 cells similarly treated resulted in profound downregulation of OCSC markers (72 to 94% at 50 µM of cisplatin), and a marked reduction in the proportion of ABCG2 and ALDH1 positive cells (~ 1%). CONCLUSIONS: We conclude that the downregulation of OCSC markers may signal a reduction in OCSC population following MMP20/DSPP silencing in OSCC cells, while also increasing their sensitivity to cisplatin. Thus, our findings suggest a potential role for DSPP and MMP20 in sustaining OCSC population in OSCCs, possibly, through mechanism(s) that alter OCSC sensitivity to treatment with chemotherapeutic agents such as cisplatin.

Role of JNK signaling in oral cancer: A mini review.

JNKs (c-Jun N-terminal kinases) belong to mitogen-activated protein kinases' family and become activated by several growth factors, stress, radiation, and other extracellular signals. In turn, JNK activation results in phosphorylation of downstream molecules involved in many normal cellular processes. Nevertheless, recent data have linked JNK signaling with several pathological conditions, including neurodegenerative diseases, inflammation, and cancer. The role of JNK in cancer remains controversial. Initially, JNK was thought to play a rather oncosuppressive role by mediating apoptosis in response to stress stimuli, inflammatory, or oncogenic signals. However, a number of studies have implicated JNK in malignant transformation and tumor growth. The contradictory functions of JNK in cancer may be due to the diversity of JNK upstream and downstream signaling and are under intensive investigation. This review summarizes current literature focusing on the significance of JNK pathway in cancer development and progression, particularly addressing its role in oral cancer. Understanding the complexity of JNK signaling has the potential to elucidate important molecular aspects of oral cancer, possibly leading to development of novel and individualized therapeutic strategies.

Expression of NF-κB and IL-6 in oral precancerous and cancerous lesions: An immunohistochemical study.

BACKGROUND: The purpose of this study was to evaluate the immunohistochemical expression of NF-κB and IL-6 in oral premalignant and malignant lesions and to investigate their possible correlation with the presence of subepithelial inflammation. MATERIAL AND METHODS: Thirty two oral premalignant lesions, clinically compatible with leukoplakia or erythroplakia, were investigated. Microscopically, 11 of them showed hyperkeratosis and acanthosis (epithelial hyperplasia) and 21 showed dysplasia of varying degrees. Nine cases of OSCC and four control cases of normal oral mucosa were also included in the study. Immunohistochemical staining with NF-κB (p65) and IL-6 was performed. IL-6 and nuclear NF-κB staining were assessed as positive or negative. For cytoplasmic localization of NF-κB, a total score combining intensity and percentage of positive epithelial cells was additionally calculated. The presence of inflammation was also recorded. RESULTS: Intensity and total scores for NF-κΒ cytoplasmic immunostaining showed a statistically significant gradual increase from normal mucosa to OSCC (p=0.012 and p=0.026 respectively). Non-statistically significant increased NF-κΒ nuclear localization was detected in dysplasias and OSCCs. Positive statistical correlation was detected between the presence of inflammation and IL-6 expression (p=0.015). No correlation between NF-κΒ and IL-6 was detected. CONCLUSIONS: NF-κΒ is activated in the early stages of oral carcinogenesis. IL-6 may have an NF-κΒ-independent role, possibly through regulation of the inflammatory response.

Phosphorylated signal transducer and activator of transcription-1 immunohistochemical expression is associated with improved survival in patients with oral squamous cell carcinoma.

PURPOSE: To estimate whether the immunohistochemical (IHC) expression patterns of the tumor suppressor gene signal transducer and activator of transcription-1 (STAT1) and its active phosphorylated form (PSTAT1) serve as potential prognostic and predictive markers in patients with oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS: STAT1 and PSTAT1 protein expressions were examined immunohistochemically in OSCC tumor tissues and adjacent normal mucosa from 49 patients who underwent primary surgery. The IHC scores were correlated with all available clinicopathologic parameters that were obtained from a maximum of 7 years of follow-up, including survival and response to adjuvant therapy treatment. RESULTS: There was a shift toward lower percentages of cells with STAT1 (P < .014) and PSTAT1 (P < .001) detected in OSCC tumors compared with adjacent normal tissue sites. No association with patients' clinicopathologic characteristics was shown. However, for the group of patients who received adjuvant chemotherapy, increased PSTAT1 intensity of staining in OSCC tumors was strongly associated with better overall survival (P = .008). CONCLUSIONS: This is the first study to concurrently evaluate STAT1 and PSTAT1 IHC expression patterns and their prognostic significance in patients with OSCC, highlighting the potential role of PSTAT1 as a biomarker in therapeutic decision making. Large prospective studies are needed to verify these findings.

Impact of COVID-19 Disease on the Development of Osteomyelitis of Jaws: A Systematic Review.

Background/Objectives: Osteomyelitis is characterized by an inflammatory process affecting both bone and bone marrow, leading to cell death and the formation of bone sequestrum. Recent literature from the past five years has documented instances of osteomyelitis following infections of SARS-CoV-2. This systematic review explores the link between osteomyelitis of the jaw (OMJ) and COVID-19 infections. Methods: This review adhered to the PRISMA guidelines, systematically analyzing literature from 2020 to 2024 sourced from databases including Medline, Embase, Scopus, and Web of Science. PROSPERO ID: CRD42024526257. Results: The review selected 42 articles, detailing 201 cases of osteomyelitis of the jaw related to COVID-19 (COMJ). The demographic breakdown included 195 male (74.4%) and 67 female patients (25.6%), with a median age of 52.7 years, ranging from 24 to 71 years. A significant portion of COMJ patients (41.5%) were hospitalized due to COVID-19, and 58.5% received corticosteroid therapy. Diabetes mellitus was a common comorbidity among COMJ patients (65.1%). Most cases involved maxilla (182 cases; 90.5%), with nearly half showing sinus involvement (49.4%). The mandible was affected in 19 cases (9.5%). Mucormycosis and aspergillosis emerged as the predominant fungal infections, identified in 103 (51.2%) and 50 (24.9%) cases, respectively. Conclusions: Individuals with pre-existing health conditions such as diabetes mellitus who have been treated for COVID-19 are at an increased risk of developing OMJ, particularly maxillary fungal osteomyelitis. COMJ poses a significant diagnostic and therapeutic challenge for dental and maxillofacial professionals, who are often the first to encounter these cases.

TGF-ß1, Smad-2/-3, Smad-1/-5/-8, and Smad-4 signaling factors are expressed in ameloblastomas, adenomatoid odontogenic tumors, and calcifying cystic odontogenic tumors: an immunohistochemical study.

OBJECTIVES: The TGF-ß/Smad signaling pathway regulates diverse cellular functions, including tooth development, and is involved in numerous pathological processes such as tumorigenesis. The aim of this study was to investigate the immunoexpression of the TGF-ß/Smad signaling pathway members in ameloblastoma (AM), calcifying cystic odontogenic tumor (CCOT), and adenomatoid odontogenic tumor (AOT). MATERIALS AND METHODS: This retrospective cross-sectional study included 65 tissue specimens: 34 AMs, 13 CCOTs, and 18 AOTs. Serial sections were immunohistochemically stained with TGF-ß1, Smad-4, Smad-1/-5/-8, and Smad-2/-3 antibodies, and a semiquantitative measurement of the positive cells was carried out by two oral pathologists using a 0-3 scale (0: no immunoreactivity, 1: <20% positive cells, 2: 20-50% positive cells, 3: >50% positive cells). RESULTS: All biomarkers studied were found significantly decreased in AM compared to CCOT and AOT. AOT and CCOT expressed Smad-1/-5/-8 more strongly compared to AM (OR = 11.66, P < 0.001 and OR = 5.34, P = 0.013, respectively), and Smad-2/-3 immunostaining was found significantly increased in CCOT (OR = 10.42, P = 0.001) and AOT (OR = 5.16, P < 0.004) compared to AM. Similarly, Smad-4 was expressed more strongly in AOT and CCOT compared to AM (P = 0.001), while AOT demonstrated a fivefold higher chance to express TGF-ß1 compared to AM (P = 0.011). CONCLUSION: TGF-ß/Smad signaling pathway is activated in AM, AOT, and CCOT. The statistically significant reduced TGF-ß1/Smad immunoexpression in AM compared to AOT/CCOT could be associated with the more aggressive biological behavior of AM including increased cell proliferation and reduced apoptosis and differentiation. Thus, the biomarkers TGF-ß, Smad-4, Smad-1/-5/-8, and Smad-2/-3 could serve as supplementary diagnostic indices between odontogenic tumors of high and low neoplastic dynamics.

Impact of COVID-19 Dentistry-Related Literature: An Altmetric Study.

INTRODUCTION: Scientific literature on COVID-19 has grown rapidly during the pandemic. The aim of this study was to provide a comprehensive overview of the popularity on the web of the available dental publications on COVID-19 and to examine associations amongst article characteristics, online mentions, and citations. MATERIALS AND METHODS: An Altmetric Explorer search was conducted for COVID-19 articles published in dental journals using 3 keywords: COVID-19, SARS-CoV-2, and pandemic. The following Altmetric data were collected: Altmetric attention score (AAS), mentions by news outlets, tweets, Mendeley readers, and Web of Science citations. Additionally, article title, type, topic, origin and open access status, journal title, quartile of impact factor (IF) distribution, and time lapse between COVID-19 pandemic onset and publication date were analysed. RESULTS: In all, 253 articles published in 48 dental journals were eligible for the study. AAS was significantly influenced by article topic, type, origin, and journal IF quartile. There was a negligible correlation between AAS and Web of Science citations. Mendeley was the only Altmetric source highly correlated with citations. CONCLUSIONS: There was substantial online interest in COVID-19 dentistry-related literature, as depicted by the AAS of the reviewed articles and social media metrics. Mendeley reader counts were highly correlated with citations, and they may therefore be valuable in research impact evaluation.

Plasma Cell Gingivitis and Its Mimics.

Plasma cell gingivitis (PCG) is an inflammatory condition that affects the gingival mucosa of the oral cavity. It is characterized by polyclonal dense plasma cell infiltrate in the connective tissue. Lesions do not respond to prophylactic treatment. Etiology is most likely hypersensitivity to certain antigens (eg, toothpastes, oral rinses, chewing gums, spices). Differential diagnosis of PCG includes reactive, granulomatous, and neoplastic lesions. The diagnostic workup is based on patient's history and the clinicopathologic correlation to rule out mimics of PCG. Dermatologic patch test may be indicated in chronic conditions to identify the allergen.

Radiologic findings of osteonecrosis, osteoradionecrosis, osteomyelitis and jaw metastatic disease with cone beam CT.

PURPOSE: The purpose of this study was to assess CBCT scans of patients with medication related osteonecrosis of the jaws (MRONJ), osteoradionecrosis (ORN), osteomyelitis (OM) and jaw metastatic disease (JM), evaluate the presence and extent of radiologic findings, identify radiologic parameters that may distinguish the four entities and last, introduce a new modified radiographic index (CRIm), in order to contribute to the diagnosis of these conditions. METHODS: Τwo major databases were retrospectively searched for fully documented and diagnosed CBCT scans of MRONJ, ORN, OM and JM from 2006 to 2019. 335 CBCT scans met the inclusion criteria and were assessed under standardized viewing conditions blindly by 2 observers. The CRIm index proposed in this study evaluates: lytic changes, sclerosis, periosteal bone formation, sequestration, non-healing extraction sockets and other findings which included: sinus implication, inferior alveolar canal implication and jaw fracture. Lytic changes, sclerosis, periosteal bone formation, sequestration and non-healing extraction sockets were scored as: absent (0), localized/single (1) and extensive/multiple (2). Each one of other findings were scored individually as: absent (0) and present (1). For statistical analysis t-test, Pearson's r correlation coefficient, one-way ANOVA and Bonferonni were performed. RESULTS: Extensive lytic changes were the most common finding, especially for ORN, where it occurred in all CBCT scans (100%). The mean value of the CRIm index differs significantly between CBCT scans with MRONJ and JM, as well as between those with OM and JM (Bonferroni p < 0.001). CONCLUSIONS: The new modified Composite Radiographic Index introduced in this study, appears to have improved an objective approach to the previously used Composite Radiographic Index by means of cumulative radiologic features. Τhe predominance of certain radiologic features in one or more of these entities may lead the diagnostician towards the correct diagnosis.

Co-existence of Congenital Epidermoid Cyst and Ranula in a Newborn. Report of a Unique Case.

Background: Congenital cystic swellings involving the floor of the mouth include various lesions such as developmental cysts (e.g., dermoid and epidermoid cysts), ranulas, vascular malformations etc. However, coexistence of such conditions, possibly with a cause-and-effect- relationship, is rare. The purpose of this case report is to present a rare case of a congenital epidermoid cyst associated with a mucous retention cyst in a newborn. Methods: A 6-month-old female infant was referred to an Oral Medicine Clinic in Athens, Greece on October 2019 for evaluation of a swelling at the floor of the mouth, first noticed by her paediatrician just after birth. Clinically, a yellowish "pearly" nodule in close association with the orifice of the left submandibular duct, posteriorly transitioning to a diffuse bluish cystic swelling of the left floor of the mouth was observed. With a provisional diagnosis of a dermoid cyst and/or ranula, a surgical excision was performed under general anaesthesia. Results: Histopathologically, a well-defined, keratin-filled, cystic cavity lined by orthokeratinized stratified squamous epithelium was observed in the anterior aspect while posteriorly and in close proximity, a dilated salivary duct lined by cylindrical, cuboidal or pseudostratified epithelium was noted. A final diagnosis of an epidermoid cyst intimately associated with a mucus retention cyst (ranula) of the submandibular duct was rendered. Conclusions: The coexistence of two cystic lesions in the floor of the mouth with features of epidermoid and mucous retention cyst, respectively, is rare and its pathogenesis intriguing, especially in a newborn.

Novel biomarker panel predicts prognosis in human papillomavirus-negative oropharyngeal cancer: an analysis of the TAX 324 trial.

BACKGROUND: New treatment strategies for locally advanced head and neck squamous cell carcinoma combine induction chemotherapy and chemoradiation. Identifying the predictors of outcome in sequentially treated patients is critical for focusing therapeutic research. In this analysis, the authors evaluated human papillomavirus type 16 (HPV-16) status and the expression levels of a defined set of biomarkers to identify predictors of response to this treatment modality. METHODS: In total, 114 patients with oropharyngeal cancer (OPC) who were treated on the TAX 324 trial (cisplatin and fluorouracil with or without docetaxel in patients with locally advanced head and neck squamous cell carcinoma) had pretreatment biopsy specimens that were evaluable for HPV-16 DNA and immunohistochemical expression of the following biomarkers: beta-tubulin II (ßT-II), glutathione S-transferase (GST-π), p53, and B-cell lymphoma 2 (Bcl-2). Patients were categorized into risk groups based on their HPV status and biomarker expression levels. RESULTS: Patients with high-risk OPC were defined by HPV-negative status and either elevated expression of ßT-II or levels of at least 2 of the other 3 adverse markers (elevated GST-π, elevated p53, or low Bcl-2). All other HPV-negative patients were categorized as moderate risk. In total, 55 patients were HPV-positive, and 59 patients were HPV-negative, with 34 were categorized as high risk and 25 categorized as moderate risk. The median survival for HPV-positive patients was not reached. The median survival was 44.2 months for moderate-risk patients (95% confidence interval, 20.9 months to not reached) and 12.1 months for high-risk patients (95% confidence interval, 7.5-19.7 months). The 24-month survival rate was 89% for HPV-positive patients, 67% for moderate-risk patients, and 29% for high-risk patients (P < .0001). CONCLUSIONS: The molecular data set in this study readily differentiated between 2 distinct groups of patients with locally advanced, HPV-negative OPC. This risk-stratification strategy may serve as a guide for treatment selection.

Secretory leukocyte protease inhibitor (SLPI) expression and tumor invasion in oral squamous cell carcinoma.

Differential expression of secretory leukocyte protease inhibitor (SLPI) impacts on tumor progression. SLPI directly inhibits elastase and other serine proteases, and regulates matrix metalloproteinases, plasminogen activation, and plasmin downstream targets to influence invasion. We examined tissues from human oral squamous cell carcinoma (OSCC) for SLPI expression in parallel with proteases associated with tumor progression and evaluated their relationships using tumor cell lines. Significantly decreased SLPI was detected in OSCC compared to normal oral epithelium. Furthermore, an inverse correlation between SLPI and histological parameters associated with tumor progression, including stage of invasion, pattern of invasion, invasive cell grade, and composite histological tumor score was evident. Conversely, elevated plasmin and elastase were positively correlated with histological parameters of tumor invasion. In addition to its known inhibition of elastase, we identify SLPI as a novel inhibitor of plasminogen activation through its interaction with annexin A2 with concomitant reduced plasmin generation by macrophages and OSCC cell lines. In an in vitro assay measuring invasive activity, SLPI blocked protease-dependent tumor cell migration. Our data suggest that SLPI may possess antitumorigenic activity by virtue of its ability to interfere with multiple requisite proteolytic steps underlying tumor cell invasion and may provide insight into potential stratification of oral cancer according to risk of occult metastasis, guiding treatment strategies.

Expression of BMP4 and FOXN1 in orthokeratinized odontogenic cyst compared to odontogenic keratocyst suggests an epidermal phenotype.

Odontogenic keratocysts (OKC) and orthokeratinized odontogenic cysts (OOC) are odontogenic cysts that share histological and immunohistochemical similarity with epidermal appendages and cutaneous cystic lesions despite exhibiting contrasting biological behavior. In epidermal appendages, BMP4 induces expression of FOXN1, which participates in terminal differentiation of keratinocytes and control of proliferation. We compared BMP4 and FOXN1 expression in OOC and OKC to investigate their role in the epithelial differentiation of these cysts. BMP4 and FOXN1 expression was assessed using immunohistochemistry in 20 primary sporadic OKC and compared to 16 OOC. BMP4 epithelial expression was detected in 81.25% OOC compared to 35% in OKC, while its expression in connective tissue was observed in 65% OKC and 75% OOC. FOXN1 was detected in 75% OOC vs. 30% OKC. The "triple positive" phenotype, i.e., BMP4 epithelial and connective tissue positivity and FOXN1 epithelial positivity, was seen in 56.25% OOC compared to 10% OKC. The greater expression of BMP4 and FOXN1 in OOC suggests greater activation of this pathway in OOC, which suggests a role in its more mature epithelium; it also resembles an epidermal phenotype.