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Previous reports of odontogenic keratocyst (OKC) and orthokeratinized odontogenic cyst (OOC) with coverage of the old literature have tended to overlook the underlying theme of the first description. From a historical viewpoint, a French paper "kyste butyreux du sinus maxillaire simulant un cancer encéphaloid" published in 1855 by Maisonneuve popularized the notion of so-called "buttery cyst", which ultimately became known as jaw cyst with a keratinized lining. Soon after in 1856, Nélaton presented a case of OKC at the Anatomical Society of Paris, but his brief communication provided little information about its histopathology. It was Mikulicz who conducted, in 1876, a pioneering descriptive pathological study of OKC. In 1886, 10 years after Mikulicz's German report, OOC was first described in detail by Jeannel of Toulouse. The mid to late decades of the nineteenth century saw notable European contributions on the topic. [ABSTRACT FROM AUTHOR]

Background: Homeobox genes play crucial roles in tooth morphogenesis and development and thus mutations in homeobox genes cause developmental disorders such as odontogenic lesions. The aim of this scoping review is to identify and compile available data from the literatures on the topic of homeobox gene expression in odontogenic lesions. Method: An electronic search to collate all the information on studies on homeobox gene expression in odontogenic lesions was carried out in four databases (PubMed, EBSCO host, Web of Science and Cochrane Library) with selected keywords. All papers which reported expression of homeobox genes in odontogenic lesions were considered. Results: A total of eleven (11) papers describing expression of homeobox genes in odontogenic lesions were identified. Methods of studies included next generation sequencing, microarray analysis, RT-PCR, Western blotting, in situ hybridization, and immunohistochemistry. The homeobox reported in odontogenic lesions includes LHX8 and DLX3 in odontoma; PITX2, MSX1, MSX2, DLX, DLX2, DLX3, DLX4, DLX5, DLX6, ISL1, OCT4 and HOX C in ameloblastoma; OCT4 in adenomatoid odontogenic tumour; PITX2 and MSX2 in primordial odontogenic tumour; PAX9 and BARX1 in odontogenic keratocyst; PITX2, ZEB1 and MEIS2 in ameloblastic carcinoma while there is absence of DLX2, DLX3 and MSX2 in clear cell odontogenic carcinoma. Conclusions: This paper summarized and reviews the possible link between homeobox gene expression in odontogenic lesions. Based on the current available data, there are insufficient evidence to support any definite role of homeobox gene in odontogenic lesions. [ABSTRACT FROM AUTHOR]

Clear Cell odontogenic Carcinomas (CCOC) are rare, aggressive malignant odontogenic tumours which are often misdiagnosed as benign odontogenic tumours due to the non-specific histologic appearance, and benign early clinical presentation. However, due to their propensity to metastasize, the best outcomes are experienced with they are diagnosed early and treated aggressively. In this paper, we present a case of a CCOC misdiagnosed as a clear cell calcifying epithelial odontogenic tumour which was only found to be a CCOC after cervical node metastasis. The original diagnosis was questioned and confirmed to be a CCOC by identification of the chromosomal translocation EWSR1 on fluorescence in situ hybridization. This has recently been described in CCOC and a wide variety of other mesenchymal and epithelial neoplasms. Previous reports have demonstrated EWSR1–ATF1 and EWSR1–CREB1 fusions in CCOC. Next generation sequencing of this case demonstrated the EWSR1–CREM fusion gene which has not been previously reported for CCOC. CREM fusion proteins have only recently been found in several tumour types including the closely associated hyalinizing clear cell carcinoma of salivary glands. This is discussed in this paper, and the role of the discovery of the CREM fusion protein in CCOC adds to your understating of the role of CREM in oncogenesis, and the possible link between CCOCs and hyalinizing clear cell carcinomas. [ABSTRACT FROM AUTHOR]

Low-grade intraductal carcinoma is a rare neoplasia with an excellent prognosis, previously classified as low-grade cribriform cystadenocarcinoma and low-grade salivary duct carcinoma. The tumor mainly occurs in the parotid gland and presents a ductal phenotype and an intraductal/intracystic growth pattern. It resembles intraductal breast lesions such as atypical ductal hyperplasia, papillary and cribriform ductal carcinoma in situ. Despite its infrequency, discriminating low-grade intraductal carcinoma from other salivary gland tumors is crucial, especially because of its favorable prognosis. A 74-year-old woman with a history of neurofibromatosis underwent a superficial parotidectomy to remove a sharply demarcated multi-cystic mass, diagnosed as category 4 at FNAC. The histological examination revealed a demarcated but unencapsulated lesion composed of a bigger cyst surrounded by several smaller cysts, lined by a monolayer or bilayer epithelium alternated with a cribriform proliferation, characterized by "Roman-bridges", with occasional micro-papillae. A myoepithelial component, with a basal disposition, was present, confirmed by intense staining for protein p63 and SMA. Immunohistochemical stains showed intense, strong uniform positivity for pan-cytokeratin, protein S100, and SOX10. The Ki67 proliferation index was low (< 10%). A diagnosis of Low-grade Intraductal Carcinoma (LGIC) of the parotid was made. We performed a literature search in PUBMED for "Intraductal carcinoma", "Low-grade Intraductal Carcinoma", "Cribriform Cystadenocarcinoma", "Salivary Duct Carcinoma", and "Low-Grade Salivary Duct Carcinoma". We selected 17 papers published between 1983 and 2020; the most affected anatomical site was the parotid gland (77/90), followed by minor salivary glands (6/90), the intraparotid lymph nodes (3/90) and the submandibular gland (4/90). Their main histopathological features are reported in the paper. Here we present a case report and a review of scientific literature on this topic to provide some essential diagnostic tools to discriminate this rare entity. [ABSTRACT FROM AUTHOR]

The eponymous history of Warthin tumor (WT) is a fascinating issue in the field of salivary gland pathology. The late decades of the nineteenth century and the turn of the century saw notable German and French contributions on WT. Especially, the seminal 1910 paper of Albrecht and Arzt of Vienna is the foundation for the current knowledge of WT. It is generally believed that prior to this pioneering study, Hildebrand of Göttingen accurately described the lesion of WT in 1895. However, the historical origins of WT appear to be unsettled, and only a few German pathologists and surgeons are aware that dating back to 1885, the first recognizable reference to WT was that by the renowned German-Swiss pathologist Zahn, whose name is eponymously associated with "Zahn infarct" and "lines of Zahn". Two noted French surgeons with a major interest in pathology, Albarrán in 1885 and Lecéne in 1908, did not contribute to the topic. Since the 1950s, a mostly American group of pathologists and surgeons gradually adopted the term WT to replace the very accurate histologic descriptor "papillary cystadenoma lymphomatosum" coined by Warthin himself in 1929. It is our opinion that from a historical viewpoint, there is no particular reason why this tumor should have been named WT. [ABSTRACT FROM AUTHOR]

Review of the literature: Cementoblastoma (CB) is unique among odontogenic tumors because its gross pathological anatomy is pathognomonic in most cases, i.e., a rounded calcified growth that is fused to the root of a tooth and completely encapsulated by fibrous tissue. The resulting radiographic appearance is a well-defined, globular mixed radiopaque/lucent or completely radiopaque mass obliterating some details of the root, with a thin radiolucent zone surrounding the central opacity. Although hundreds of publications have covered the clinicopathologic features of CB, almost nothing is known about its true history. Also it seems there is little understanding about how the term "CB" was originally introduced as a pathologic entity. This report covers some overlooked papers on CB dating back to the 19th century, including the first complete description in 1888 and the first radiographic presentation in 1906. [ABSTRACT FROM AUTHOR]

Background: Desmoplastic melanoma is a rare subtype of melanoma mainly appearing on sun-exposed skin. Clinically, it is many times non-pigmented and therefore the diagnosis is often not suspected. Methods: Review article. Results: In this paper we review the main histopathological, immunohistochemical, and molecular features of desmoplastic melanoma, as well as the top 10 morphologic differential diagnoses which should be considered in most cases. The histopathological pattern can be many times deceptive, mimicking a scar, a fibrous reaction, a fibrohistiocytic tumor such as a dermatofibroma, a vascular tumor such as angiosarcoma, a smooth muscle tumor such as leiomyosarcoma, or a neural tumor. Although an overlying atypical junctional melanocytic proliferation may be seen in most cases, it is absent in a significant percentage (up to 30%) of cases, making the diagnosis even more difficult in those instances. The range of diagnostic pitfalls is wide, which may present disastrous prognostic consequences. Conclusion: Desmoplastic melanoma is often a difficult diagnosis to make, as it frequently shows nonspecific clinical findings and overlapping histologic features with many other tumors. However, the potential clinical and prognostic consequences of misdiagnosis as another entity are great. Therefore, this diagnosis must always be kept in mind when encountering spindle cell tumors affecting the head and neck area. [ABSTRACT FROM AUTHOR]

Nasal chondromesenchymal hamartoma (NCMH) is a very rare, benign sinonasal tract tumor commonly affecting infants. In this paper, in addition to presenting a systematic review of the literature on NCMH, we also report an unusual case of NCMH in an adolescent patient. A systematic review conducted following the PRISMA guidelines. PubMed, EMBASE and manual search through references of relevant publication were utilised to gather all published case-reports of NCMH. Data collected from each case-report for patient demographics, site and size of NCMH, clinical presentation, co-morbidities, diagnostic methods, treatment options and follow-up methods. The systemic review collected sixty-two case-reports of NCMH (including our case) affecting 42 men and 21 women (2:1 male to female ratio). Mean average age was 5.1 years (age range: 1 day to 70 years). The anatomical sites of the tumor were: nasal cavity (n = 17), paranasal sinuses (n = 30), orbital region (n = 17), and the base of the skull (n = 16). The reported clinical manifestations were nasal obstruction or congestion (n = 29), nasal mass (n = 27), epistaxis (n = 6), orbital symptoms (n = 14). NCMH is a very rare cause of nasal masses in infants and toddlers. Our case and previous case reports confirm that NCMH can mimic other benign and malignant tumors, therefore we should be vigilant for rare pathologies that lead to nasal masses. Recently the link between DIECR1 mutation with NCMH has been established, so NCMH should be considered in any patient with nasal or orbital symptoms with a history of DICER1-related tumor spectrum. [ABSTRACT FROM AUTHOR]

Peripheral or extraosseous odontogenic tumors are rare oral soft tissue enlargements which demonstrate the same histologic features of their intraosseous counterparts but emerge in gingiva and mucosa. In this paper we report a case of peripheral odontoma in a 12-years-old female patient presented asymptomatic swelling in the palatal site. After the clinical and radiographic examination, excisional biopsy was applied to the lesion located entirely in the soft tissue of maxillary incisors. Histopathologically presence of tooth-like structures containing dentin with regular canals and partly enamel matrix were observed. Our aim is to present the extremely rare case of peripheral odontoma and to review the literature for demonstrating the frequency and clinicopathologic features of this entity. [ABSTRACT FROM AUTHOR]

Clear cell Odontogenic Carcinoma (CCOC) is an uncommon malignant odontogenic tumor (MOT). It is the fifth most common MOT. A systematic review is presented of reported cases, case series and retrospective studies of CCOC, to determine trends in presentation, diagnostic features, treatment, and patient outcome. Searches of detailed databases were carried out to identify papers reporting CCOC. The variables were demographics, patient symptoms, tumor location, histopathological findings, immunohistochemical studies, treatment, follow-up, and recurrence. 117 cases were identified; CCOC was most frequently seen in mature females 65% (n = 76). The total average age was 55.4 with a range from 17 to 89 years, for females 56.4 and males 53.6 years. The mean size was 3.41 cm. The most common location was in the mandibular body 36.2% (n = 42), followed by the anterior mandible 23.3% (n = 27). The most common clinical presentation was a swelling 80.4% (n = 74), and the main symptom was pain 41.3% (n = 31), followed by painless lesion 24% (n = 18). The most common Immunohistochemistry positive expression was CK19, EMA, and CEA, and for special staining periodic acid Shiff (PAS); 97% of cases were treated surgically. The average follow-up was 30.3 months, and recurrence was reported in 52.4% of the cases. Conclusion: CCOC shows a strong predilection for the body and anterior mandible, and females are more frequently affected. CCOCs can be painful and the principle clinical sign is swelling, CCOCs can metastasize, and the prognosis is fair. [ABSTRACT FROM AUTHOR]

We aimed to collect and analyze available cases of intraoral acantholytic squamous cell carcinoma (aSCC), that consisted of the authors' cases and cases derived from the existing literature, with an emphasis on the pathological staging and patient outcome. Our research question was whether aSCC is more aggressive than conventional SCC. The literature was searched for documented cases of aSCC involving the intra-oral mucosa, excluding those from the lips and tonsils, and seven new cases were added from our files. The authors compared the obtained aSCC data to existing data for conventional SCC. Fisher Exact or Pearson's χ2 tests were used for categorical variables. Fifty-five cases of intraoral aSCC were reviewed, of which 48 were retrieved from the literature. Analysis of the published cases was reinforced by contacting the authors of all the papers with incomplete data for further clarifications. The most common sites of aSCC were the tongue (24/55) and the maxilla/maxillary gingiva and/or palate (11/55). The overall survival rate was 36/53 (67.9%) with a mean follow-up period of 22 months against 62.5% for conventional SCC (p = 0.6). No statistically significant difference between the two variants of the tumor with respect to the oral cavity was detected. The differences in age, sex, survival rate, staging, and locations were not statistically significant. Based on the available data from 55 cases, there is no evidence to suggest that aSCC is more aggressive than conventional SCC in intraoral cases. [ABSTRACT FROM AUTHOR]

Leishmaniasis is a parasitic disease considered an endemic public health problem in developing countries, where it is a reportable disease. Isolated oral manifestation is rare, and its clinical manifestations are variable. In this paper we describe an unusual case of an immunocompetent patient, 57-year-old man with a painless reddish submucosal nodule located on the tongue dorsum. Microscopical analysis showed chronic inflammatory infiltrate with macrophages containing leishmania in cytoplasmic vacuoles. PCR assays confirmed the diagnosis and patient was treated with meglumine antimoniate for 30 days. Absence of the parasite was confirmed by PCR. Thirteen years after treatment, a scar fibrosis persisted on the tongue dorsum. The case reported reveals that leishmaniasis should be considered in the diagnosis of tongue nodules in immunocompetent patients. [ABSTRACT FROM AUTHOR]

Glandular odontogenic cysts are rare odontogenic cysts with a wide range of histopathological features. In this paper we describe the clinical and pathological features of an unusual case of a glandular odontogenic cyst with metaplastic cartilage. The previous literature of odontogenic cysts presenting with metaplastic cartilage is reviewed alongside a discussion of the differential diagnoses. To our knowledge this is the first reported case of a glandular odontogenic cyst with metaplastic cartilage. [ABSTRACT FROM AUTHOR]

Lymphoid and histiocytic lesions of the head and neck in pediatric patients is a fascinating topic as most of these lesions are benign, but that the neoplastic cases are essential to diagnose accurately for appropriate treatment. It is thought that 90% of children will have palpable lymph nodes between the ages of 4 to 8; most, but not all, are non-malignant and some resolve spontaneously without treatment. This paper will look at many of the benign and malignant lesions of both lymphocytic and histiocytic origin that present in the head and neck of children focusing on their diagnostic criteria. There is a very pertinent discussion of nonmalignant lymphoid proliferations, as infections and other reactive conditions dominate the pathology of pediatric lymphohistiocytic head and neck lesions. Discussion of those lymphomas which arise more frequently in the head and neck focuses on those seen in children and young adults such as classic Hodgkin lymphoma and Burkitt lymphoma, as well as new more controversial entities such as pediatric-type follicular lymphoma. Histiocytic lesions, both benign and malignant, are described and may be challenging to diagnose. [ABSTRACT FROM AUTHOR]

Vascular anomalies, further classified into vascular tumors and malformations, often involve the head and neck region of children. These entities may raise diagnostic dilemmas, as they often demonstrate heterogenous and overlapping histologic features. The aim of this paper is to provide an overview of the common vascular anomalies in the head and neck region of children. Specific entities discussed include infantile hemangioma, congenital hemangioma, tufted angioma, kaposiform hemangioendothelioma, and various vascular malformations. Clinicopathologic features and associated molecular associations are reviewed. [ABSTRACT FROM AUTHOR]

Vestibular schwannoma (VS) is a Schwann cell-derived tumour arising from the vestibulocochlear nerve. Although benign, it represents a threat to intracranial structures due to mass effect and carries a small risk of malignant transformation. VS therefore represents an important healthcare burden. We review the literature regarding pathogenesis, risk factors, and diagnosis of VS. The current and future potential management strategies are also discussed. A narrative review of all relevant papers known to the authors was conducted. The majority of VS remain clinically stable and do not require interventional procedures. Nevertheless, various surgical techniques exist for removing VS, the most common of which are translabyrinthine and retrosigmoid approaches. Due to surgical risks such as hearing loss, facial nerve dysfunction, post-operative headache, and cerebrospinal fluid leakage, a "watch and rescan" approach is adopted for most patients. Radiotherapy is a useful alternative and has been shown to have a similar response for growth restriction. Due to the heterogeneous nature of VS, there is a lack of consensus regarding management of tumours that are too large for conservative management but too small to indicate surgery. Emerging biologic therapies, such as Bevacizumab, Everolimus, and Lapatinib, as well as anti-inflammatories like aspirin are promising potential treatments; however, long-term evidence of their efficacy is required. The knowledge base regarding VS continues to improve. With increased understanding of the pathogenesis of these tumors, we believe future work should focus on pharmacologic intervention. Biologic therapies aimed toward improved patient outcomes are particularly promising. [ABSTRACT FROM AUTHOR]

Odontogenic myxomas often have a distinctive radiographic presentation described as a "soap bubble", "tennis racket", or "honeycomb" pattern. Less frequently, examples of odontogenic myxomas with a "sunray" or "sunburst" pattern have been reported. Because malignant entities such as osteosarcomas more classically present with a sunray/sunburst appearance, odontogenic myxomas are rarely considered in the radiographic differential diagnosis of a sunburst lesion. The objective of this paper is to report a case of an odontogenic myxoma presenting with a sunburst appearance and to review similar reported cases in the literature. To the best of the authors' knowledge, this additional case of an odontogenic myxoma presenting with a sunburst appearance brings the total number of sunray/sunburst cases reported in the English language literature to 21. [ABSTRACT FROM AUTHOR]

Juvenile mandibular chronic osteomyelitis (JMCO) is a rare, idiopathic disease of chronic bone inflammation without suppuration, sinus tract formation, or sequestration. As the name suggests, this condition predominately affects children. The few cases of JMCO reported in the literature describe different treatments, and thus a standard therapy protocol has not yet been established. The aim of this paper is to report a clinical case in a 9-year-old girl that was misdiagnosed and unsuccessfully treated for 1 year. After experiencing persistent symptoms, a correct diagnosis was subsequently rendered based on the physical and radiographic examination as well as successful treatment with non-steroidal anti-inflammatory drugs (NSAIDs). The patient received drug therapy followed by periods of remission over a 4 year follow-up period. Diagnosis and treatment of JMCO is a challenge given the rarity and nonspecific signs and symptoms of this condition. Treatment with NSAIDs and regular follow-up is a conservative option for these patients. [ABSTRACT FROM AUTHOR]

Human papilloma virus (HPV)-positive oropharyngeal squamous cell carcinomas (OPSCC) tend to have good outcomes, however a subset does not share this favourable prognosis. The aim of this paper is to investigate the utility of tumour cell anaplasia and multinucleation as prognostic markers in oropharyngeal squamous cell carcinoma. Retrospective review of 104 patients with OPSCC or squamous cell carcinoma of unknown primary site (SCCUP) who underwent primary resection and/or lymph node dissection. Slides of both primary and nodal metastatic disease were assessed for the presence of anaplasia and multinucleation. 53 patients were HPV-positive. Anaplasia was more frequent in males (p = 0.005), smokers (p = 0.003), and HPV-negative disease (p = 0.04). HPV status and > 10 pack-year smoking history were independent predictors of recurrence-free survival (RFS) and disease-specific survival (DSS). Neither anaplasia, nor multinucleation, at the primary site or in cervical metastases, had any significant impact on RFS or DSS. We did not find either anaplasia or multinucleation to have any significant prognostic impact in OPSCC. However, given the small number of adverse events in the HPV-positive cohort, we may have lacked sufficient power to detect significance in what was the subgroup of primary interest. Our study highlights the challenge of identifying markers of poor prognosis in HPV-positive OPSCC. [ABSTRACT FROM AUTHOR]

Orthokeratinized odontogenic cysts (OOC) are developmental odontogenic cysts characterised by an orthokeratinized stratified squamous epithelial lining. They were originally believed to be part of the spectrum of Odontogenic Keratocyst, but are now considered to be a distinct entity. They are rare, making up approximately 1% of all odontogenic cysts and they usually occur singly. In this paper we present two new cases of multiple OOCs, and compare them to previous case reports of multiple lesions. The clinical and pathological features are discussed, along with possible diagnostic pitfalls. [ABSTRACT FROM AUTHOR]

The use of diverse terminology may lead to inconsistent diagnosis and subsequent mistreatment of lesions within the proliferative verrucous leukoplakia (PVL) spectrum. The objectives of this study were: (a) to measure inter-observer variability between a variety of pathologists diagnosing PVL lesions; and (b) to evaluate the impact of diverse terminologies on understanding, interpretation, and subsequent treatment planning by oral and maxillofacial surgeons (OMFS). Six oral pathologists (OP) and six head and neck pathologists (HNP) reviewed 40 digitally scanned slides of PVL-type lesions. Inter-observer agreement on diagnoses was evaluated by Fleiss' kappa analysis. The most commonly used diagnostic terminologies were sent to ten OMFS to evaluate their resulting interpretations and potential follow-up treatment approaches. The overall means of the surgeons' responses were compared by Student t test. There was poor inter-observer agreement between pathologists on the diagnosis of PVL lesions (κ = 0.270), although there was good agreement (κ = 0.650) when diagnosing frankly malignant lesions. The lowest agreement was in diagnosing verrucous hyperplasia (VH) with/without dysplasia, atypical epithelial proliferation (AEP), and verrucous carcinoma (VC). The OMFS showed the lowest agreement on identical categories of non-malignant diagnoses, specifically VH and AEP. This study demonstrates a lack of standardized terminology and diagnostic criteria for the spectrum of PVL lesions. We recommend adopting standardized criteria and terminology, proposed and established by an expert panel white paper, to assist pathologists and clinicians in uniformly diagnosing and managing PVL spectrum lesions. [ABSTRACT FROM AUTHOR]

The diagnosis of osteomas in the paediatric population can pose a challenge to pathologists in excluding malignant bony tumours. We present the case of a 10-year old male presenting with a large left mandibular radiopaque lesion. This paper discusses the case of a central osteoma with osteoblastoma-like features, literature review, differential diagnosis of radiopaque lesions of the maxilla and mandible as well as a detailed discussion of the pathology of the lesion. Although similar lesions have been described in the sino-orbital region, this is believed to be the first report of this pathological entity in the mandible. [ABSTRACT FROM AUTHOR]

Excluding human papillomavirus (HPV)-driven conditions, oral papillary lesions consist of a variety of reactive and neoplastic conditions and, on occasion, can herald internal malignancy or be part of a syndrome. The objectives of this paper are to review the clinical and histopathological features of the most commonly encountered non-HPV papillary conditions of the oral mucosa. These include normal anatomic structures (retrocuspid papillae, lingual tonsils), reactive lesions (hairy tongue, inflammatory papillary hyperplasia), neoplastic lesions (giant cell fibroma), lesions of unknown pathogenesis (verruciform xanthoma, spongiotic gingival hyperplasia) and others associated with syndromes (for instance Cowden syndrome) or representing paraneoplastic conditions (malignant acanthosis nigricans). Common questions regarding differential diagnosis, management, and diagnostic pitfalls are addressed, stressing the importance of clinico-pathologic correlation and collaboration. [ABSTRACT FROM AUTHOR]

Lesions of the gingivae are amongst the commonest lesions seen in patients and the vast majority are reactive hyperplasias, related to a number of chronic irritant stimuli. However, there are a number of entities that have a predilection for the gingivae, which are much less common in other parts of the oral cavity. The purpose of this paper is to discuss the clinical and histological differential diagnoses when presented with a lump on the gingivae, including the approach to diagnosis and diagnostic pitfalls. [ABSTRACT FROM AUTHOR]

An important inconsistency currently exists in the literature on oral cancer. Reviewing this literature, one finds that the term oral cancer is defined and described with great variation. In a search in PubMed, at least 17 different terms were found for titles of papers reporting data on oral cancer. The variability of the terms used for designating anatomic regions and type of malignant neoplasms for reporting oral cancer has hampered the ability of researchers to effectively retrieve information concerning oral cancer. Therefore, it is sometimes extremely difficult to provide meaningful comparisons among various studies of oral cancer. Recently, a new ontological strategy that is rooted in consensus-based controlled vocabularies has been proposed to improve the consistency of data in dental research (Smith et al. in J Am Dent Assoc 141:1173-1175, ). In this paper, we analyzed the terminology dilemma on oral cancer and explained the current situation. We proposed a possible solution to the dilemma using an ontology-based approach. The advantages for applying this strategy are also discussed. [ABSTRACT FROM AUTHOR]

Background The reporting of thyroid carcinomas follows the recommendations of the College of American Pathologists (CAP) protocols and includes papillary carcinoma, follicular carcinoma, anaplastic carcinoma and medullary carcinoma. Despite past and recent efforts, there are a number of controversial issues in the classification and diagnosis of thyroid carcinomas (TC) that, potentially impact on therapy and prognosis of patients with TC. Discussion The most updated version of the CAP thyroid cancer protocol incorporates recent changes in histologic classification as well as changes in the staging of thyroid cancers as per the updated American Joint Commission on Cancer staging manual. Among the more contentious issues in the pathology of thyroid carcinoma include the defining criteria for tumor invasiveness. While there are defined criteria for invasion, there is not universal agreement in what constitutes capsular invasion, angioinvasion and extrathyroidal invasion. Irrespective of the discrepant views on invasion, pathologists should report on the presence and extent (focal, widely) of capsular invasion, angioinvasion and extrathyroidal extension. These findings assist clinicians in their assessment of the recurrence risk and potential for metastatic disease. It is beyond the scope of this paper to detail the entire CAP protocol for thyroid carcinomas; rather, this paper addresses some of the more problematic issues confronting pathologists in their assessment and reporting of thyroid carcinomas. Conclusion The new CAP protocol for reporting of thyroid carcinomas is a step toward improving the clinical value of the histopathologic reporting of TC. Large meticulous clinico-pathologic and molecular studies with long term follow up are still needed in order to increase the impact of microscopic examination on the prognosis and management of TC. [ABSTRACT FROM AUTHOR]

Background: A recent systematic review published in Head and Neck Pathology found that 3.8% of dentinogenic ghost cell tumors harbor duct-like/ cribriform architecture. Herein we discuss this finding regarding the differential diagnosis of this tumor with adenoid ameloblastoma. Methods: A critical review of some microscopic findings reported in a recent paper published in the Head and Neck Pathology Journal was done. Results: Although there are overlapping microscopic features with dentinogenic ghost cell tumor, adenoid ameloblastoma is distinguished by the combination of duct-like structures and whorls/morules. In our opinion, at least some cases previously diagnosed as dentinogenic ghost cell tumors may now be more accurately classified as adenoid ameloblastoma. Conclusion: We conclude that a reassessment of dentinogenic ghost cell tumor cases using the diagnostic criteria proposed by the new WHO classification of Head and Neck Tumors (2022) is warranted. [ABSTRACT FROM AUTHOR]

Salivary adenocarcinoma, not otherwise specified (AdCaNOS) is a rare malignant tumor with potential diagnostic challenge, which mainly affects the parotid glands; however, the minor salivary glands can also be involved by AdCaNOS. This paper reports a case of a 45-year-old Afro-descendant woman complaining of a slow-growing mass with 6 months of evolution in the left superior vestibular fornix. Microscopic examination revealed an infiltrative epithelial neoplasm composed of predominantly solid growth pattern, arranged in a lobular configuration, admixed with glandular or ductal structures. Perineural invasion was evident. The tumor cells were polygonal or oval showing focally mild nuclear pleomorphism, and eosinophilic or clear cytoplasm. Notably, some areas exhibited intracytoplasmic pigment granules mainly in non-luminal cells, as well as sebaceous-like cells, discrete hyaline material deposition and foci of infiltration of residual salivary gland parenchyma. Tumor cells were negative for PAS, mucicarmine and Alcian blue stains. By immunohistochemistry, the tumor cells were diffuse and strongly positive for pan-cytokeratin (CK) AE1/AE3, 34betaE12 CK, vimentin, p63 and S100. CK7 and EMA strongly highlighted the ductal structures. Solid areas also showed diffuse and moderate expression of CD56. Podoplanin (D2-40), GFAP and Calponin, followed by DOG-1, were focally positive; whereas CK20, α-SMA, h-Caldesmon, CD57, ERBB2/HER2 and p53 were negative. Ki-67 was < 2%. Consecutive serial tissue sections using CD57 confirmed the perineural invasion. Positivity for HMB-45 and MART-1/Melan-A, as well as Fontana-Masson stain (and potassium permanganate bleaching-sensitive), identified the pigment granules as melanin. To the best of our knowledge, this is the first case of intraoral low-grade AdCaNOS with intracytoplasmic melanin granules. [ABSTRACT FROM AUTHOR]

Sialadenoma papilliferum (SP) is a rare benign salivary gland neoplasm that comprises from 0.4 to 1.2% of all salivary gland tumors. The tumor is so named because of its microscopic resemblance to the syringocystadenoma papilliferum, an uncommon benign tumor of sweat gland origin. The purpose of this paper is to report the clinical and microscopic features of seven new cases of SP and combine them with cases previously reported in the English language literature to further define this unusual lesion. Combining our cases with acceptable cases from the literature, the palate (especially the hard palate) was the most common site, with 80% of the cases occurring in this location. Other locations in decreasing order were buccal mucosa, upper lip, retromolar pad, and parotid gland. Age at diagnosis ranged from 18 to 87 years with a peak in the 6th decade and an average age of 56.4 years. Microscopically, the lesions demonstrated a papillary surface morphology, and the papillary projections varied from long and pointed to short and blunted. The supporting connective tissue contained a variable number of convoluted ductal structures, which often fused with the overlying surface epithelium. The ductal structures exhibited papillary infoldings and were lined by a double layer of epithelium consisting of basal cell layer and a luminal layer of cuboidal-to-columnar ductal cells. Immunohistochemical reactivity with p63 and p40 indicated that the basal cell layer was comprised predominantly of neoplastic myoepithelial cells. The luminal cells were immunoreactive with epithelial membrane antigen characteristic of ductal cell differentiation. Conservative surgical treatment was accomplished in most cases and appears to be adequate treatment as only two recurrences were documented. Several case reports of purported malignant transformation in SP have been reported in the literature, but in our opinion, there is insufficient evidence in the publications to unequivocally determine whether any of the malignancies truly originated within a pre-existing SP. [ABSTRACT FROM AUTHOR]

The differential diagnosis for clear cell neoplasms of the sinonasal tract is wide but critical to understand. In this paper, we describe a case of renal cell-like adenocarcinoma (SNRCLA) presenting as a paranasal sinus mass with clear cell morphology. The relevant literature is reviewed and the workup for clear cell neoplasms described. SNRCLA is a rarely encountered low grade glandular malignancy of the paranasal sinuses. Despite its morphologic mimicry of renal cell carcinoma, SNRCLA demonstrates a seromucinous phenotype and is associated with a favorable prognosis and low recurrence rates after surgical resection. [ABSTRACT FROM AUTHOR]

Lichen sclerosus (LS) is a chronic inflammatory mucocutaneous disease that often affects the anogenital area and causes significant discomfort and morbidity. Oral mucosal lesions in LS are extremely rare and might be associated with genital and/or skin manifestations. As a unique manifestation of LS, oral lesions are even more rare, with only 20 cases reported in English-language literature. In reviewing that literature in this paper, we present the case of a 44-year-old white man who sought dental assistance with a complaint of a white spot on his upper lip. Extraoral clinical examination revealed a slight white macule on the left upper lip vermilion next to the labial commissure. Intraoral examination revealed that the macule was approximately 3.5 × 2.0 cm, extended to the upper left labial mucosa, and presented an ivory-white color. Following an incisional biopsy and microscopy, the lesion was shown to be covered by a stratified squamous epithelium showing hyperkeratosis and atrophy. The superficial lamina propria revealed a well-marked band of subepithelial hyalinization and, below it, a band-like mononuclear inflammatory infiltrate. Sections stained by Verhoeff's technique revealed a scantiness of elastic fibers in the superficial lamina propria. The diagnosis of LS was then established. The patient was referred for dermatologic evaluation, which identified no skin or genital lesions, and no treatment was employed. After 6 years, no significant changes in clinical features were observed. Altogether, this rare case makes an important contribution to knowledge on this uncommon condition. [ABSTRACT FROM AUTHOR]

The sinonasal tract remains an epicenter of a diverse array of neoplasia. This paper discusses changes to the WHO classification system of tumors involving this area. In particular, seromucinous hamartoma, NUT carcinoma, biphenotypic sinonasal sarcoma, HPV-related carcinoma with adenoid cystic features, SMARCB1-deficient carcinoma, and renal cell-like adenocarcinoma are discussed. [ABSTRACT FROM AUTHOR]

The unique chequered pattern of elephant ivory has made it a desired commodity for the production of various works of art. The demand however outstrips the supply and with soaring prices, illegal tusk harvesting is thriving on the African continent. Formal restrictions placed on trade in elephant products have been ineffective in reversing the rapid decline in elephant numbers. We are presently facing the reality of extinction of free roaming elephant on the African continent. This paper describes the histogenesis of the chequered pattern, the genomic impact of ivory harvesting on the phenotype of breeding herds, and the contribution of science to tracing the origin of illegal ivory. [ABSTRACT FROM AUTHOR]

Epithelioid multinodular osteoblastoma is a rare variant of osteoblastoma characterized by numerous nodules of epithelioid osteoblasts surrounding bony trabeculae, as well as clusters of epithelioid osteoblasts without osteoid formation. It commonly occurs in the gnathic bones of the face and spine, and has a male predominance. To date, only 26 cases of epithelioid multinodular osteoblastoma have been reported and described in detail in the literature. Lucas et al. (Hum Pathol 25:117-134, ) described 43 cases of a variant of osteoblastoma that he termed epithelioid multifocal osteoblastoma. These both likely represent the same entity. Here, we report another case of this rare variant of osteoblastoma. An 18-year-old male patient presents with a periapical radiolucency in the region of vital tooth #30. The surgeon's differential diagnosis for this radiolucent lesion was ameloblastoma versus cyst. An incisional biopsy of the lesion revealed well-vascularized fibrous connective tissue containing a multinodular tumor composed of collections of epithelioid cells with osteoblastic differentiation surrounding zones of hyalinization and bony trabeculae. Multinucleated giant cells and rare typical mitotic figures were noted. Additionally present within the tumor were clusters of epithelioid osteoblasts without bony trabeculae. Residual immature viable bone trabeculae were noted surrounding the tumor. A diagnosis of epithelioid multinodular osteoblastoma was rendered. In this paper we present a rare case of epithelioid multinodular osteoblastoma of the mandible, provide a general review of the literature, and highlight the unique histological features that help differentiate this tumor from tumors classified as conventional osteoblastoma, aggressive osteoblastoma, pseudoanaplastic osteoblastoma and, most importantly, low-grade or osteoblastoma-like osteosarcoma. [ABSTRACT FROM AUTHOR]

Several benign and malignant mesenchymal and meningothelial lesions may preferentially affect or extend into the sinonasal tract. Glomangiopericytoma (GPC, formerly sinonasal-type hemangiopericytoma) is a specific tumor with a predilection to the sinonasal tract. Sinonasal tract polyps with stromal atypia (antrochoanal polyp) demonstrate unique histologic findings in the sinonasal tract. Juvenile nasopharyngeal angiofibroma (JNA) arises from specialized tissue in this location. Meningioma may develop as direct extension from its intracranial counterpart or as an ectopic tumor. Selected benign mesenchymal tumors may arise in the sinonasal tract and pose a unique differential diagnostic consideration, such as solitary fibrous tumor and GPC or lobular capillary hemangioma and JNA. Although benign and malignant vascular, fibrous, fatty, skeletal muscle, and nerve sheath tumors may occur in this location, this paper focuses on a highly select group of rare benign sinonasal tract tumors with their clinicopathological and molecular findings, and differential diagnosis. [ABSTRACT FROM AUTHOR]

Synovial chondromatosis (SC) is a chronic process, defined as a reactive cartilaginous proliferation, characterized by formation of cartilaginous nodules, usually loose in the joint space of the synovial membrane. It mainly affects large joints such as knee, hip, shoulder, and elbow, commonly in male patients. However, its manifestation in the Temporomandibular joint (TMJ), is a rare finding, occurring predominantly in females. This paper reports a case of a woman who presented to the service of Stomatology complaining of mouth opening limitations and pain in her left pre-auricular region. After clinical and radiographic analyses, the condition was diagnosed as SC of the TMJ. The loose bodies within the TMJ were removed under general anesthesia. Histological and follow-up features of this lesion are also discussed. To our knowledge, this is the second report of SC of the TMJ in Brazil. [ABSTRACT FROM AUTHOR]

Oral mucosal melanoma is a relatively rare malignancy with an aggressive clinico-pathological behaviour. The mean 5-year survival rate is about 15 %. It arises primarily from melanocytes found in the basal cell layer of the epithelium, but may sometimes arise from melanocytes residing in the lamina propria. The pathogenesis is complex, and few of the molecular mechanisms underlying the development of oral mucosal melanoma have been defined. The extraneous risk factors associated with oral mucosal melanoma, if any, are unknown. Oral mucosal melanomas account for about 25 % of all mucosal melanomas of the head and neck, and exhibit a profile of cytogenetic alterations, and a pathobiological behaviour and clinical course different from that of cutaneous melanomas. As they are usually painless and grow quickly, as a rule, they are diagnosed late in the course of the disease when the lesions are already large and have metastasized to regional lymph nodes. In this paper we discuss some aspects of the pathobiology of oral mucosal melanoma, and present an illustrative case report. [ABSTRACT FROM AUTHOR]

Follicular dendritic cell sarcoma (FDCS) of the parapharyngeal space is a rare malignant tumor. Only eleven cases of FDCS of the parapharyngeal space have been reported in English literature. Most of the reported cases developed tumor recurrence within 1 year or had metastasis. Because of the rarity of FDCS in the parapharyngeal space and peculiar histology, it can be misdiagnosed as undifferentiated carcinoma or meningioma. Therefore, pathologists should be aware of the existence of FDCS in this location. This paper aims to report a unique case of FDCS of the parapharyngeal space without recurrence in 26 months follow up with a review of the literature. [ABSTRACT FROM AUTHOR]

Sarcomas of the larynx are exceedingly uncommon, of which primary laryngeal osteosarcomas are the rarest. To date, 25 cases of primary laryngeal osteosarcomas have been reported in the literature. Laryngeal osteosarcomas may closely simulate sarcomatoid carcinomas, since both entities share clinical, histological and immunohistochemical features. Herein, we report a case of primary laryngeal osteosarcoma in a 55 year old male, focusing on the importance of light microscopic, immunohistochemical and ultrastructural features in accurately establishing the diagnosis. In addition, the current paper provides a review of the English language literature on the subject. Laryngeal osteosarcomas usually carry a dismal prognosis with no general consensus on the most effective mode of therapy. Similarly, the current patient developed bilateral lung metastases 8 months after the initial surgery. [ABSTRACT FROM AUTHOR]

Synovial chondromatosis of the temporomandibular joint is rare. Even less commonly documented is the progression of synovial chondromatosis to a synovial chondrosarcoma. The aim of this paper is to present only the third case of synovial chondrosarcoma of the temporomandibular joint. Distinction between these two entities by histology alone is extremely difficult and even though it is advised that the definitive diagnosis should be based on clinical, radiographic and histological evidence, this has proved not to be so simple. The patient, a 63 year old female presented with a swelling associated with her left temporomandibular joint. CT and MRI scans confirmed the presence of a periauricular chondroid mass. Fine needle aspiration biopsy revealed an atypical chondroid lesion that was supicious for a chondrosarcoma. The left temporomandibular joint and surrounding tissues were resected after further imaging and extensive clinical, radiological and cytologic consultations. A diagnosis of synovial chondrosarcoma arising in synovial chondromatosis was made. [ABSTRACT FROM AUTHOR]

The clinical features and common molecular alterations of adenoid cystic carcinoma (ACC) are reviewed in this paper. ACC is an uncommon neoplasm that most frequently arises in salivary glands and related tissue in the head and neck region. ACC has distinct histologic features, with cribriform and tubular growth patterns of basaloid cells displaying a predominantly myoepithelial cellular phenotype. This neoplasm also has uncommon clinical features of rare regional lymph node metastasis and a prolonged but relentlessly progressive clinical course. Clinical outcome in ACC is correlated to histologic grade, which is correlated to the degree of aneuploidy and genetic alterations present in the tumor genomes. Recent studies have identified that the majority of ACC contain alterations of the MYB gene, usually resulting in a fusion gene product with the NFIB gene by a t(6;9) translocation event. The molecular consequences of this alteration are incompletely understood, as are secondary molecular alterations that contribute to the neoplastic phenotype of ACC. [ABSTRACT FROM AUTHOR]

As part of this symposium honoring Leon Barnes, the authors were asked to present the case from which they learned the most. I chose a cystic sebaceous lymphadenoma (SL) as my case presentation. This paper presents this unusual case, as well as several additional sebaceous tumors that came across my desk the first few years I was in practice. These interesting cases led me to thoroughly review the literature on sebaceous tumors of the salivary glands, resulting in several publications, the largest series of sebaceous tumors published at this time as well as a careful review of all cases in the literature. The author will also review the current and previous literature on the five types of salivary gland sebaceous tumors: sebaceous adenoma, SL (and non-sebaceous lymphadenoma), sebaceous carcinoma, sebaceous lymphadenocarcinoma, and sebaceous differentiation in other types of salivary gland lesions. [ABSTRACT FROM AUTHOR]

Elastofibromas of the oral cavity are rare, with only 5 cases reported. In this paper, we present a series of five new cases of oral elastofibromatous lesions, occurring in 4 males and 1 female, with ages ranging from 33 to 76 years. The clinical differential diagnosis includes fibroepithelial polyp or fibroma, among other connective tissue tumours. Elastofibromas probably develop as reactive lesions, for which surgical treatment is definitive. [ABSTRACT FROM AUTHOR]

The peripheral calcifying odontogenic cyst (PCOC) accounts for less than 25% of the cases of calcifying odontogenic cysts and most commonly appears as a nodule on the gingiva. This paper aims to present both a case report of a PCOC located in the left vestibular maxilla as well as a review of the English-language literature. An 11-year-old female patient presented a swelling in the vestibular region of teeth 12 and 13. Periapical and panoramic radiographs demonstrated irregular calcification. Surgical excision was performed. Microscopic examination showed an odontogenic cystic lesion lined by ameloblastoma-like epithelium, containing numerous ghost cells. Areas of calcification associated with ghost cells could also be observed. The patient was diagnosed with PCOC. The patient has been disease-free for 36 months. The review of the cases of PCOC showed 44 well-defined cases. The mean age was of 49.4 years at the time of diagnosis. The reported cases appeared as a painless swelling, with a slight predilection for females, and were more frequently located in the anterior region of the maxilla or mandible. Surgical excision is the treatment of choice, and recurrence is rare. [ABSTRACT FROM AUTHOR]

Odontogenic myxoma is a rare benign but locally aggressive odontogenic tumor. This report describes a case of odontogenic myxoma producing diffusely dispersed calcified products in a pattern reminiscent of a fibro-osseous lesion of the jaw. Differential diagnoses for myxoid lesions of the jaws also are discussed. This paper highlights how an odontogenic myxoma can produce a large amount of calcified products to mimic a fibro-osseous process. [ABSTRACT FROM AUTHOR]

After a 12 year interval from the previous fascicle, a new fascicle on Tumors of the Salivary Glands in the new fourth series of the AFIP Atlas of Tumor Pathology was published in 2008. The data, presentation, illustrations, tables, and physical characteristics of the newest fascicle have been updated and improved. There have only been a few alterations and additions to the classification of tumors and tumor-like non-neoplastic conditions of salivary gland. Three of the most significant are discussed in this paper. Sialoblastoma has been reclassified as malignant; inflammatory pseudotumor has been reclassified as neoplastic and re-identified as inflammatory myofibroblastic tumor; and sclerosing polycystic adenosis is a new entity among tumor-like conditions. [ABSTRACT FROM AUTHOR]

This paper provides a review of the more common tumors to metastasize to 12 anatomic subsites of the head and neck, exclusive of cervical lymph nodes. Emphasis is placed on clinical rather than subclinical metastases discovered at autopsy. [ABSTRACT FROM AUTHOR]

Odontogenic tumors composed of two or more distinct types of lesions are unusual. In this paper, a case of an odontogenic lesion characterized by simultaneous occurrence of areas of calcifying odontogenic cyst (COC) and orthokeratinized odontogenic cyst (OOC) is described. The lesion was asymptomatic and presented at the radiographic examination as a unilocular well-delimited radiolucency extending from left incisor to right premolar area in the mandible. To date, this is the first report of COC associated with an OOC. [ABSTRACT FROM AUTHOR]

Solitary fibrous tumour (SFT) is a rare tumour principally found in adults in the pleural cavity. Extrapleural occurrences are rare. Two cases of SFT of the thyroid gland are described in this paper showing their distinctive microscopical architecture, namely “patternless growth pattern”. It is characterized by a bland spindle-cell proliferation alternating hyper- and hypo-cellular areas, keloid-like hyalinization and a focal hemangiopericytoma-like vascular pattern. Tumour cells revealed a diffuse strong positivity for CD34, CD99, bcl-2 and Vimentin, but negativity for Desmin, EMA, AE1/AE3, SMA, S-100 and CD31 antibodies. The differential diagnosis of thyroid SFT includes different types of spindle cell proliferation, benign and malignant mesenchymal tumours, medullary thyroid carcinoma, fasciitis-like papillary carcinoma, and undifferentiated (anaplastic) carcinoma. However, the morphologic and immunohistochemical findings of SFT are so characteristic that this diagnosis seldom represent a difficulty. [ABSTRACT FROM AUTHOR]

Molecular alterations in tumors have become interesting targets both for diagnostic and for therapeutic and prognostic applications in tumor pathology. In the head and neck, there are a variety of different alterations, encompassing all the different types of genetic events associated with carcinogenesis. This paper reviews three different types of tumors that display a spectrum of genetic alterations: the translocation in Mucoepidermoid carcinoma, Epstein Barr virus association in nasopharyngeal carcinoma, and the HRPT2 tumor suppressor gene in parathyroid carcinoma. Basic histology is reviewed and the genetic alterations are discussed, along with a brief discussion of potential diagnostic implications. [ABSTRACT FROM AUTHOR]