Xanthoma of the Jaw Bones: Cases Series and Review of Literature.

BACKGROUND: Intraosseous xanthomas are rare benign lesions sometimes associated with excess lipid production. Xanthoma of the jaw bones (XJB) was first reported in 1964, and fewer than 50 cases have been reported in the English literature to date. The etiopathogenesis of XJB is highly suggestive of a reactive process or a metabolic condition. METHOD: Seven cases of XJBs were retrieved from the archives of 4 oral and maxillofacial pathology services. Clinical, radiographic and histopathologic features of all these cases were retrospectively analyzed. Immunohistochemical (IHC) stains for S100 and CD68 were performed. RESULTS: All seven cases involved the mandible. Patients' age ranged between 13 and 69 years with an evenly distributed female to male ratio. One patient had a medical history of hyperlipidemia, but the medical and dental histories of the others were unremarkable. For most cases, XJB was an incidental finding discovered during routine radiographic examination. Swelling and cortical expansion were noted in a few cases. Radiographically, cases typically presented as either well-defined multilocular or unilocular lesions, which were either radiolucent or mixed radiolucent/radiopaque. All the lesions were treated with surgical curettage and no recurrence was observed during subsequent follow-ups. Each of the seven cases exhibited sheets of foamy macrophages. The diagnosis is established by exclusion of entities with overlapping microscopic features and involved correlation with the clinical, histological, radiographic and IHC profiles. Immunohistochemically, all the cases expressed diffuse positivity for CD68 and were negative for S100. CONCLUSION: XJB is a rare lesion of unknown etiology, which may mimic other benign or reactive jaw lesions. Due to its rarity and the potential diagnostic challenges it presents, clinicians must remain vigilant and consider CXJ in their differential when assessing radiolucent jaw anomalies.

Sustainable and Eco-Friendly DLC Fabrication for Replacing Chrome on a Gravure Cylinder Surface.

This paper evaluates the potential of diamond-like carbon (DLC) as a durable surface protection to replace the chromium (Cr) layer, which is traditionally applied to gravure print cylinders and other components through a galvanic electroplating process. The fabrication of DLC is more eco-friendly and could reduce the environmental hazard posed by hexavalent chromium in liquid form that is used in Cr application and better adhere to environmental regulations. This could encourage businesses to bring the DLC fabrication process in-house, sharing resources such as materials, labor, and equipment, to help reduce costs. Four DLC variants (standard DLC, A-DLC, S-DLC, and organic silica) and chrome were analyzed and tested for their surface properties and durability. Data suggest that both standard DLC and S-DLC had higher surface free energy, allowing for good ink wetting on the surface when compared to chrome. In addition, the standard DLC and S-DLC surfaces are generally smoother than the chrome, resulting in lower relative hydrophilicity and allowing for easier removal of ink in the nonimage regions with the doctor blade. The elcometer adhesion test demonstrated that the bond strength of the DLC variants to their base layer was comparable to the bond strength of chrome, indicating that the adhesion strength of the two materials was similar. Furthermore, in the abrasion test, the wear on the standard DLC surface and the corresponding wear on the lamella tip of the metal doctor blades were notably lower than that observed on chrome. This distinction is particularly evident in each of the test trials, specifically run 1, which involved 2,000,000 wiping actions of a metal doctor blade in the presence of abrasive TiO2 ink pigments. Statistical analysis on standard DLC versus chrome suggests that DLC fabrication is effective and durable on plain and patterned surfaces. Therefore, from a sustainable and eco-friendly perspective, standard DLC and S-DLC would be good alternative durable surfaces for print cylinders and other components used in various industries due to superior wear resistance properties.

COVID-related mucormycosis mimicking dental infection.

A recent increase in the prevalence of mucormycosis of the head and neck in patients who have recovered from COVID-19 following hospitalization has been reported. A Majority of the cases have been reported from India. Conditions such as diabetes mellitus, use of corticosteroids for other autoimmune conditions, organ transplant, immunosuppression, immunodeficiency, and malignancies especially hematologic ones, are all known risk factors for mucormycosis. Recently, hospitalization for COVID-19 has been added to the list of risk factors for opportunistic mucormycosis infection. This is likely attributable to the high doses and prolonged use of corticosteroids in the treatment of hospitalized COVID-19 patients. Case Description: Two patients with post-COVID-19 associated rhinocerebral mucormycosis presented with profound unexplained dental disease including tooth mobility and dental abscess mimicking periodontal disease. The patients were previously hospitalized for COVID-19 and received prolonged treatment with high doses of corticosteroids. The patients responded well to the surgical debridement with or without antifungal therapy. Conclusion: Oral healthcare providers including oral and maxillofacial surgeons, dentists, dental hygienists, and other dental practitioners can play a vital role in the recognition and early diagnosis of rhinocerebral mucormycosis given the large number of patients with severe COVID-19 infection who have recovered following hospitalization and/or received long-term high doses of immunosuppressive treatment.

A rare case of peripheral adenoid ameloblastoma with dentinoid.

Adenoid ameloblastoma with dentinoid (AAD) is an extremely rare central neoplasm of the gnathic bones with no reported case of peripheral AAD. Adenoid ameloblastoma with dentinoid was first reported by Slabbert et al. in 1992 under the term "dentinoameloblastoma." However, the Armed Forces Institute of Pathology introduced the name "adenoid ameloblastoma with dentinoid" in 1994. Histologically, AAD shows features of ameloblastoma and adenomatoid odontogenic tumor along with a calcified product resembling dentin. The biological behavior of central AAD is not well established, though, in the literature, several reports consider it to be among the more aggressive odontogenic neoplasms, with a propensity for local invasion and recurrence. The demographic characteristics, clinical features, behavior, and prognosis of the peripheral AAD (PAAD) are unknown. To the best of our knowledge, this is the first reported case of PAAD in a 62-year-old woman.

Oral Melanoacanthoma: Case Series of 33 Cases and Review of the Literature.

BACKGROUND: Oral melanoacanthoma (OM) is a rare, reactive, and benign proliferation of two cell types: keratinocytes and melanocytes. Biopsy is mandatory to not only confirm the diagnosis but also, rule out other entities, as clinical correlation simply, is not definitive. AIM OF THE STUDY: We present a large series of OM with analysis of demographics, clinical appearance, histologic presentation, and review of the literature. To the best of our knowledge, this is the largest series of oral OM reported to date. MATERIALS AND METHODS: Following IRB approval, cases diagnosed as OM within the archives of the University of Florida Oral Pathology Biopsy Service (1998-2020) were included. Patient age, gender, location, clinical appearance, clinical impression, and duration of each lesion was collected. RESULTS: A total of 33 cases were included with a mean age of 38.7 years (range of 5-73), and a female: male ratio of 2.6:1. The most common location in descending order was the buccal mucosa (n = 16, 48%), followed by palate (n = 11, 33%), tongue and labial mucosa (n = 2 each, 6%), maxillary and mandibular gingiva (n = 1 each, 3%). The lesions were most frequently brown/black in color, and most often described as macular. All cases were asymptomatic and reported duration was ranged from one week to twelve months. Clinical impression in descending order was pigmented macules (n = 15, 45%), melanosis (n = 4, 12%), nevus (n = 3, 9%), melanoma (n = 2, 6%), melanoacanthoma (n = 1, 3%), and racial pigmentation (n = 1, 3%). Ethnicity was only documented in only 6 out of 33 cases, of which 5 cases were African-American and one Caucasian. The majority of cases (n = 28, 84%) demonstrated hyperplastic/acanthotic surface epithelium with less common, atrophic (n = 4, 12.1%) or spongiotic epithelium (n = 2, 6.06%). CONCLUSION: The demographics and clinical presentation of OM in our series was similar to previous findings but encompasses wider variability of histologic presentation. Awareness of OM in the clinical and histologic differential diagnosis of pigmented lesions should be reinforced as many patients are concerned for melanoma and clinicians are often unware of this condition.

Mechanisms of γδ T cell accumulation in visceral adipose tissue with aging.

γδ T cells are resident in visceral adipose tissue (VAT) where they show an age-associated increase in numbers and contribute to local and systemic chronic inflammation. However, regulation of this population and mechanisms for the age-dependent accumulation are not known. In this study, we identified a progressive trend of γδ T cell accumulation in VAT over the lifespan in mice and explored physiological mechanisms contributing to accumulation. Using isochronic parabiotic pairs of wild-type (WT) and T cell receptor delta knockout (TCRδ KO) mice at young and old age, we confirmed that VAT γδ T cells are predominately a tissue-resident population which is sustained in aging. Migration of peripheral γδ T cells into VAT was observed at less than 10%, with a decreasing trend by aging, suggesting a minor contribution of recruitment to γδ T cell accumulation with aging. Since tissue-resident T cell numbers are tightly regulated by a balance between proliferation and programmed cell death, we further explored these processes. Using in vivo EdU incorporation and the proliferation marker Ki67, we found that the absolute number of proliferating γδ T cells in VAT is significantly higher in the aged compared to young and middle-aged mice, despite a decline in the proportion of proliferating to non-proliferating cells by age. Analysis of apoptosis via caspase 3/7 activation revealed that VAT γδ T cells show reduced apoptosis starting at middle age and continuing into old age. Further, induction of apoptosis using pharmacological inhibitors of Bcl2 family proteins revealed that VAT γδ T cells at middle age are uniquely protected from apoptosis via a mechanism independent of traditional anti-apoptotic Bcl2-family proteins. Collectively, these data indicate that protection from apoptosis at middle age increases survival of tissue-resident γδ T cells resulting in an increased number of proliferative cells from middle age onward, and leading to the age-associated accumulation of γδ T cells in VAT. These findings are important to better understand how adipose tissue dysfunction and related changes in the immune profile contribute to inflammaging among the elderly.

Understanding the zebras of wound care: an overview of atypical wounds.

Atypical wounds account for approximately 5% to 20% of chronic ulcerations. Typically, clinical suspicion of an uncommon etiology is warranted for wounds that do not show signs of healing with conventional care, that are associated with pain out of proportion to the clinical presentation, or that are atypical in appearance. This review provides a general overview of various atypical wound etiologies, clinical presentations and appearance, and current treatment protocols. The clinical presentation, pathophysiologic etiology, and current literature on each etiology are presented. The etiologies discussed are pyoderma gangrenosum, calciphylaxis, lichen planus, necrobiosis lipoidica, infectious ulcers, hidradenitis suppurativa, artefactual ulcers, hydroxyurea-induced ulcers, vasculopathies, and neoplastic ulcers. Patients with atypical wounds experience a poorer prognosis and slower healing rate compared with patients with typical wound etiologies (eg, vascular and diabetic wounds). Biopsy is often vital in wound care to identify and differentiate wound etiologies. It is important to note that multiple characteristics or histologic features can overlap in a biopsy with atypical wounds. Therefore, a biopsy will still require an understanding of the presentation of these different wounds and should only be used when appropriate. The proper diagnosis for an atypical wound can greatly hasten wound closure, decrease the cost for the patient and the health care system, and improve the patient's quality of life. Because of the limited availability of patient populations with atypical wound etiologies, literature concerning specific pathologies is limited. More research on each pathology is needed, as is a universally accepted treatment protocol for atypical wounds.

Accumulation of γδ T cells in visceral fat with aging promotes chronic inflammation.

Adipose tissue dysfunction is strongly linked to the development of chronic inflammation and cardiometabolic disorders in aging. While much attention has been given to the role of resident adipose tissue immune cells in the disruption of homeostasis in obesity, age-specific effects remain understudied. Here, we identified and characterized a population of γδ T cells, which show unique age-dependent accumulation in the visceral adipose tissue (VAT) of both mice and humans. Diet-induced obesity likewise increased γδ T cell numbers; however, the effect was greater in the aged where the increase was independent of fat mass. γδ T cells in VAT express a tissue-resident memory T cell phenotype (CD44hiCD62LlowCD69+) and are predominantly IL-17A-producing cells. Transcriptome analyses of immunomagnetically purified γδ T cells identified significant age-associated differences in expression of genes related to inflammation, immune cell composition, and adipocyte differentiation, suggesting age-dependent qualitative changes in addition to the quantitative increase. Genetic deficiency of γδ T cells in old age improved the metabolic phenotype, characterized by increased respiratory exchange ratio, and lowered levels of IL-6 both systemically and locally in VAT. Decreased IL-6 was predominantly due to reduced production by non-immune stromal cells, primarily preadipocytes, and adipose-derived stem cells. Collectively, these findings suggest that an age-dependent increase of tissue-resident γδ T cells in VAT contributes to local and systemic chronic inflammation and metabolic dysfunction in aging.

Changing Trends in Benign Human Papillomavirus (HPV) Related Epithelial Neoplasms of the Oral Cavity: 1995-2015.

Human papillomavirus (HPV)-related benign papillary epithelial neoplasms are common lesions affecting any region of the oral cavity. This study evaluated the trends in frequency, location, and demographics of these lesions over 20 years in a large biopsy service. Following IRB approval, the archives of UF Oral Pathology Biopsy Service between 1995 and 2015 were queried. Cases diagnosed as squamous papilloma, verruca vulgaris, and condyloma acuminatum were included. Extraoral locations, inconclusive diagnoses, or syndrome-related HPV lesions were excluded. Age, gender, location, clinical presentation, and diagnoses were recorded. Data from one calendar year per 5-year span was assessed including the years 1995, 2000, 2005, 2010, and 2015. A total of 1458 cases were identified over the total 5 calendar years assessed. Papilloma as a percentage of total biopsies per year was as follows: 1995 (2.6%), 2000 (3.3%), 2005 (3.6%), 2010 (4.0%) and 2015 (4.5%), representing a 73% (1.9×) percentage increase. Males (56%) were affected more commonly; however, in patients under 19 years, a female predominance was observed. The overall percentage of lesions in females increased by 30.6% over the time frame. The mean age was 54 years (range 1-93 years) with an increase of 10 years over time. About 1.1% of patients had multifocal lesions and 0.2% had a recurrence. In descending order of frequency, the tongue, soft palate, and mandibular gingiva were most involved. Maxillary gingiva and lower lip were the most common locations in patients under 19. Location varied over time, however, the biggest increase was noted for lesions on the gingiva. Squamous papilloma was the most common histologic variant (93.6%). The incidence of benign HPV-related oral lesions increased substantially over the 2 decades studied. This increase was statistically significant with a p-value <0.00045. Other trends noted included increase in the following: the average age, female involvement, and gingival location. Our results indicate a trend for the overall increase in the prevalence of benign oral HPV lesions in our population.

Essentials of oral manifestations of leukemia for the dental practitioner.

Oral lesions may be the initial or only manifestation of leukemia and can be the key to early diagnosis. The varied nature of presenting signs and dentists' general lack of familiarity with oral presentations makes diagnosis challenging. This retrospective review reports a series of cases of leukemia to familiarize dentists with the oral manifestations and facilitate earlier diagnosis or recognition of relapse of this life-threatening disease. Following institutional review board approval, the University of Florida Oral Pathology Biopsy Service archive from 1994 to 2018 was queried for all oral biopsies resulting in a diagnosis of leukemia. Cases with insufficient diagnostic information or extraoral manifestations were excluded. Demographic, clinical, and histologic findings were tabulated. Ten cases with 12 biopsy sites were identified. Men (n = 6) were affected more commonly. The mean age of the patients was 58.4 years (range of 17 to 88 years). The gingiva was the most frequently biopsied site (n = 6; 50%). Importantly, 40% of the patients (n = 4) had no prior diagnosis of leukemia. A wide spectrum of clinical impressions was rendered, pyogenic granuloma being the most common, and the reported duration of lesions ranged from several weeks to 6 months. The rarity of patients presenting with leukemia may lead to low levels of clinical suspicion, misdiagnosis, and delays in treatment. However, oral lesions may be the first and only manifestation of leukemia, and clinicians should be aware of the clinical characteristics of these oral presentations to ensure early diagnosis and treatment, thereby helping to reduce disease-related morbidity and mortality.

Buccal bifurcation cyst: A case series and review of the literature.

INTRODUCTION: Buccal bifurcation cyst is an inflammatory odontogenic cyst and constitutes up to 5% of all odontogenic cysts. The aim of this study was to report a series of cases, review the recent literature, and facilitate recognition and proper treatment of this entity. METHODS: With institutional review board approval, the authors retrieved all archival cases of buccal bifurcation cyst from the oral pathology biopsy service from 1994 through 2018. Patient age and sex, cyst location, clinician's impression, radiographic appearance, diagnosis, and treatment data were recorded. RESULTS: A total of 10 cases were identified. Average patient age was 9 years. A slight male predilection was observed (n = 6, 60%). One hundred percent of cases were in the mandible, including 3 (30%) bilateral cases. CONCLUSIONS: Mandibular buccal bifurcation cyst is an important entity in pediatric patients but may be less likely to be recognized by clinicians not regularly treating children. The results of this study are mostly consistent with the literature. Treatment is typically via enucleation or even more conservative modalities, and extraction should be avoided if possible. PRACTICAL IMPLICATIONS: Buccal bifurcation cysts should be treated via enucleation or even more conservative methods. If possible, the affected teeth should be preserved.

Adenomatoid odontogenic tumor: a series of 28 cases from a biopsy service.

OBJECTIVE: Adenomatoid odontogenic tumor (AOT) is a benign odontogenic tumor with an excellent prognosis, often seen in children and young adults. The aim was to examine the spectrum of clinical, radiographic, and histologic attributes of AOT and assess clinician recognition of this entity. In addition, diagnostic considerations and treatment modalities were explored. METHOD AND MATERIALS: With Institutional Review Board approval, archival cases of AOT from the University of Florida Oral Pathology Biopsy Service (1994-2019) were examined. Clinical and demographic data along with accompanying radiographs and original slides were reviewed. RESULTS: A total of 28 cases of AOT were identified. These were all solitary in nature, with a mean age of 20.6 years (range 12-67 years). Most patients were under 20 (75.0%) with a definite female predilection (64.3%). Anterior jaws remained the most common location (85.2%), with a higher maxillary predilection (57.1%). Clinical impression included odontogenic lesions such as dentigerous cyst, lateral periodontal cyst, and odontogenic keratocyst. CONCLUSION: The spectrum of features of AOT is described. As clinicians were unfamiliar with AOT, highly characteristic features of AOT and more unique variants are discussed extensively to improve diagnostic aptitude. Clinicians must remain aware of this entity, as treatment is minimal compared to other odontogenic entities.

Central odontogenic fibroma in association with brown tumor of hyperparathyroidism in a patient with neurofibromatosis type 1.

We present a patient with bone abnormalities and a myriad of lesions secondary to his redeveloping renal failure and neurofibromatosis type 1 (NF1). A 21-year-old male renal transplant recipient with NF1 presented with painless masses and large, irregular radiolucent lesions in the maxilla and mandible. After histologic examination, the lesion was diagnosed as a central odontogenic fibroma (COdF) in association with a central giant cell lesion, most consistent with brown tumor of hyperparathyroidism. The bone changes were interpreted to be highly suggestive of renal osteodystrophy. Around 30 cases of hybrid central giant cell granuloma-like lesion in association with central odontogenic fibroma have been reported. This, to our knowledge, is the first reported case of brown tumor in association with COdF. Our case provides further evidence of the giant cell component as the initiating entity in these hybrid lesions.

Peripheral ameloblastic fibro-odontoma-Report of 2 cases of a very rare entity.

Ameloblastic fibro-odontoma (AFO) is a rare benign mixed odontogenic tumor that affects children and young adults. AFO occurs mainly intraosseous. Extraosseous AFO is extremely rare. We report 2 cases of rare peripheral ameloblastic fibro-odontoma in 2- and 12-year-old female patients. Microscopic examination revealed a benign proliferation of odontogenic epithelium associated with a dentinoid material distributed within a cell-rich mesenchymal stroma resembling dental papilla. Simple surgical excision of the lesion is usually curative. There was no recurrence after a short period of follow-up. Clinicians should be cognizant of this rare entity, which can be considered in a differential diagnosis of gingival growths that are noted in early childhood.

Labial salivary gland assessment in idiopathic pulmonary fibrosis patients with sicca symptoms.

OBJECTIVE: Patients with idiopathic pulmonary fibrosis (IPF) commonly present with sicca symptoms. This study aimed to assess labial minor salivary glands (LMSGs) in those patients to rule out Sjögren's syndrome (SS), in which sicca symptoms are the clinical hallmark. STUDY DESIGN: Cases of patients with IPF with sicca symptoms referred to the oral medicine clinic at the University of Florida within the last 13 years were selected with institutional review board approval. Demographic characteristics, clinical findings, laboratory results, and histomorphologic parameters were retrospectively analyzed. RESULTS: A total of 12 patients (9 men and 3 women, ages 55-76 years) were identified. History of exposure to asbestos or chemicals, smoking, and medication information was obtained. All patients reported sicca symptoms with 57% of those exhibiting objective or borderline dryness. Anti-SSA/Ro and anti-SSB/La were positive in 25% and 8% of the cases, respectively. Microscopically, 1 out of 12 patients was biopsy positive in the absence of anti-SSA/Ro, fulfilling the 2016 SS criteria with positive sialometry. CONCLUSIONS: A LMSG biopsy is critical to identify SS in patients with diagnosed IPF and present sicca symptoms, especially those with negative serology, as revealed in our study.

Secretory Carcinoma of the Oral Cavity: A Retrospective Case Series with Review of Literature.

Secretory carcinoma (SC) is an uncommon salivary gland neoplasm of the oral cavity that microscopically may mimic acinic cell carcinoma (ACC) and mucoepidermoid carcinoma (MEC). This study describes a series of SC in minor glands with a literature review. We performed a retrospective search for oral SC, within the archives of the University of Florida, Oral Pathology and Surgical Pathology Biopsy services from 2010 to 2018. A total of 10 SCs were identified in the oral and maxillofacial region, four of which were in the minor salivary glands. The demographic, clinical, histological, and molecular findings were aggregated for all 4 cases. Patient age varied from 30 to 60 years, with an average of 45 years. Two cases each were in female and male patients. Two cases presented on the labial mucosa, and one each on the hard and soft palate. Immunohistochemical (IHC) staining showed mammaglobin positivity in all cases, GATA3 positivity in two cases, S100 positivity in three cases, and SOX10 positivity in only one case. Fluorescence in situ hybridization demonstrated positivity for ETV6-NTRK3 fusion in 4 cases. Although oral SC is rare, pathologists should be aware of the histologic overlap between the SC and other salivary gland neoplasms such as ACC and MEC. A judicious application of IHC staining would aid in diagnosis. SC should be considered in the differential diagnosis for intraoral salivary gland tumors.

Calcifying epithelial odontogenic tumor: a case series spanning 25 years and review of the literature.

OBJECTIVE: The calcifying epithelial odontogenic tumor (CEOT) is a rare benign neoplasm that makes up less than 1% of all odontogenic tumors. This study aims to describe a case series of CEOT spanning 25 years and to review and compare our results with the existing literature. STUDY DESIGN: With institutional review board approval, all CEOT archival cases from the University of Florida Oral Pathology Biopsy Service between 1994 and 2019 were retrieved. A total of 20 cases were included. Based on current criteria, 2 cases that stained positively for CD1 a were excluded, because these most likely represented the amyloid-rich variant of central odontogenic fibroma. RESULTS: Average patient age was 40 years. Females and males were affected equally (n = 10). The mandible was more commonly involved (60%, n = 12) than the maxilla (40%, n = 8). CEOT variants included incipient CEOT (10%, n = 2) and peripheral CEOT (10%, n = 2). One case exhibited features of adenomatoid odontogenic tumor in addition to CEOT. Congo red staining for amyloid was performed in 13 cases, all of which were positive. CONCLUSION: Our results align with the literature. Awareness of the different variants of CEOT and of the separate but similar-appearing amyloid-rich variant of central odontogenic fibroma will help to ensure accurate diagnosis and appropriate treatment.

Proliferative Verrucous Leukoplakia: An Expert Consensus Guideline for Standardized Assessment and Reporting.

The many diverse terms used to describe the wide spectrum of changes seen in proliferative verrucous leukoplakia (PVL) have resulted in disparate clinical management. The objective of this study was to produce an expert consensus guideline for standardized assessment and reporting by pathologists diagnosing PVL related lesions. 299 biopsies from 84 PVL patients from six institutions were selected from patients who had multifocal oral leukoplakic lesions identified over several years (a minimum follow-up period of 36 months). The lesions demonstrated the spectrum of histologic features described in PVL, and in some cases, patients developed oral cavity squamous cell carcinoma (SCC). An expert working group of oral and maxillofacial and head and neck pathologists reviewed microscopic features in a rigorous fashion, in combination with review of clinical photographs when available. The working group then selected 43 single slide biopsy cases for whole slide digital imaging (WSI) review by members of the consensus conference. The digital images were then reviewed in two surveys separated by a washout period of at least 90 days. Five non-PVL histologic mimics were included as controls. Cases were re-evaluated during a consensus conference with 19 members reporting on the cases. The best inter-observer diagnostic agreement relative to PVL lesions were classified as "corrugated ortho(para)hyperkeratotic lesion, not reactive" and "SCC" (chi-square p = 0.015). There was less than moderate agreement (kappa < 0.60) for lesions in the "Bulky hyperkeratotic epithelial proliferation, not reactive" category. There was ≥ moderate agreement (> 0.41 kappa) for 35 of 48 cases. This expert consensus guideline has been developed with support and endorsement from the leadership of the American Academy of Oral and Maxillofacial Pathology and the North American Society of Head and Neck Pathologists to recommend the use of standardized histopathologic criteria and descriptive terminology to indicate three categories of lesions within PVL: (1) "corrugated ortho(para)hyperkeratotic lesion, not reactive;" (2) "bulky hyperkeratotic epithelial proliferation, not reactive;" and (3) "suspicious for," or "squamous cell carcinoma." Classification of PVL lesions based on a combination of clinical findings and these histologic descriptive categories is encouraged in order to standardize reporting, aid in future research and potentially guide clinical management.