Frequent and differential mutations of the CYLD gene in basal cell salivary neoplasms: linkage to tumor development and progression

Wnt/β-catenin activation by mutually exclusive FBXW11 and CTNNB1 hotspot mutations drives salivary basal cell adenoma

Basal cell adenoma (BCA) and basal cell adenocarcinoma (BCAC) of the salivary gland are rare tumours that can be difficult to distinguish from each other and other salivary gland tumour subtypes. Using next-generation sequencing, we identify a recurrent FBXW11 missense mutation (p.F517S) in BCA that is mutually exclusive with the previously reported CTNNB1 p.I35T gain-of-function (GoF) mutation with these mutations collectively accounting for 94% of BCAs. In vitro, mutant FBXW11 is characterised by defective binding to β-catenin and higher protein levels within the nucleus. This is consistent with the increased nuclear expression of β-catenin and activation of the Wnt/β-catenin pathway. The genomic profiles of BCAC are distinct from BCA, with hotspot DICER1 and HRAS mutations and putative driver mutations affecting PI3K/AKT and NF-κB signalling pathway genes. These findings have important implications for the diagnosis and treatment of BCA and BCAC, which, despite histopathologic overlap, may be unrelated entities.

Correlation between basal cell adenoma and basal cell adenocarcinoma of the salivary gland: a histomorphological and molecular review of 129 cases

Basal cell adenoma (BCA) and basal cell adenocarcinoma (BCAC) are salivary gland tumors with biphasic differentiation, composed of luminal ductal cells and abluminal basal cells with a high nuclear-to-cytoplasmic ratio. While BCA is a relatively common benign tumor, BCAC is a rare malignancy, and its genetic context and relationship with BCA remain unclear. We investigated 93 BCA and 36 BCAC cases to further characterize these two tumor entities from histological and molecular perspectives. BCA/BCAC proliferated in a mixture of tubular, trabecular, solid, cribriform, and membranous patterns. A jigsaw puzzle pattern, peripheral palisading, S100-positive stroma, cystic change, and sclerosis were observed in approximately 50% of the cases. BCAC demonstrated the following malignant features: infiltration to surrounding tissue, tumor necrosis, and increased mitotic activity (81%, 22%, and 22%, respectively). The nuclear expression of β-catenin was frequently observed in both BCA and BCAC (89% and 60%), and CTNNB1 hotspot mutations were detected in 46% and 48% of BCA and BCAC cases, respectively. Tubular patterns of growth, jigsaw puzzle patterns, peripheral palisading, S100-positive stroma, and cystic changes were more common in β-catenin-positive BCA/BCAC than in β-catenin-negative BCA/BCAC. Among the β-catenin-negative BCA/BCAC cases, one case each harbored PLAG1 and MYB rearrangements. We concluded that β-catenin-positive BCA and BCAC share common histologic and molecular features, and BCAC is considered a malignant counterpart of BCA. β-Catenin-negative BCA/BCAC might include morphological mimickers, which can be genetically classified into other tumor types, including pleomorphic adenoma and adenoid cystic carcinoma.

Comparative transcriptomics of salivary basal cell adenoma and adenocarcinoma sustain linear neoplastic evolution and intertumor heterogeneity: classification and biological implications

It remains uncertain whether basal cell adenoma (BCA) and basal cell adenocarcinoma (BCAC) of the salivary gland represent two distinct neoplasms or temporal stages of a single entity. The issue is central to reconciling their shared phenotypic resemblance and protracted behavior with current pathologic classification. We conducted a transcriptomic analysis on a cohort of both pathologic forms and correlated the findings with the clinicopathologic features using RNA extracted from fresh frozen samples of 25 salivary basal tumors (five BCAs and 20 BCACs) and eight instances of metastatic basal cell carcinomas (BCCs) to parotid glands. Unsupervised analysis revealed shared and intertumoral transcriptome differences within and between BCA and BCAC and distinct segregation from metastatic dermal BCC. Transcriptomic profiling delineated two intermixed subgroups of salivary basal cell neoplasms (SBNs); SBN-I group enriched with adverse pathologic features and SBN-II that lacked any of these features except for a single case. The category with the most instances of adverse pathologic features (SBN-I) manifested upregulations of transcriptional factors linked to cell proliferation pathways (HOXB13, SOX21, MYB, and EN1 genes), while those lacking adverse pathologic features (SBN-II) demonstrated a high expression of the TFAP2B transcription- and differentiation-related pathways. Our transcriptomic findings support common neoplastic evolution and intertumoral heterogeneity of both pathologic forms of basal cell neoplasms and identify molecular pathways of potential biological and clinical significance. We therefore propose a nondeterministic designation of 'basal cell salivary neoplasms, noninvasive (adenoma)/invasive (adenocarcinoma)' as a platform that integrates conventional phenotypic classification and transcriptomic characteristics pending a classification consensus. © 2025 The Pathological Society of Great Britain and Ireland.

CYLD-mutated anal squamous cell carcinoma: An uncommon entity associated with cylindroma-like morphology and adverse clinical features

Anal squamous cell carcinoma (SqCC) can be broadly divided into HPV-positive and HPV-negative groups, each with distinct clinicopathologic features and outcome. CYLD-mutant anal SqCC was recently characterized as having a strong association with cylindroma-like histologic features, HPV positivity, infrequent PIK3CA mutation, and low tumor mutational burden. The prognostic impact of CYLD mutation in this context has not been established. We performed CYLD mutational analysis on a cohort of 109 clinicopathologically well-characterized cases of anal SqCC including 98 HPV-positive and 11 HPV-negative carcinomas. CYLD mutation was present in 3 cases (2.8 % of total, 3.1 % of HPV-positive cases), all of which were HPV16-positive. CYLD mutation was significantly associated with more frequent cylindroma-like basement membrane inclusions (p = 0.0002) and basaloid cytomorphology (p = 0.017). Just 4 % of CYLD-wildtype carcinomas demonstrated cylindroma-like features, which were limited in extent relative to CYLD-mutant cases. Among the HPV-positive group, CYLD mutation and cylindroma-like morphology were associated with a higher rate of metastatic disease progression (p = 0.022 and p = 0.01, respectively), with 2 of 3 CYLD-mutant patients developing liver metastasis at 6 and 7 months after initial diagnosis. None of the CYLD-mutant cases had other mutations including PIK3CA and TP53 mutations. Our findings further establish CYLD-mutant anal SqCC as an infrequent but distinct clinicopathologic entity with characteristic pathogenetic features and a possible association with adverse clinical outcomes. Among HPV-positive anal SqCC, CYLD mutation represents a potentially useful novel marker for this distinct entity and cylindroma-like morphology serves as a useful feature to identify such cases.

The basaloid-spectrum of salivary gland tumors: A focused review with practical diagnostic considerations

Basaloid salivary gland neoplasms are a diverse and varied group of benign and malignant tumors. The term 'basaloid' is broadly used in reference to cells with elevated nuclear to cytoplasmic ratio, sparse cytoplasm, and hyperchromatic nuclei. However, a subset may also fit within the "small round blue cell tumor" morphologic category or the "biphasic" salivary gland tumor category. Furthermore, there are no established thresholds for the proportion of basaloid tumor cells needed to consider a tumor within the basaloid spectrum. Given the implicit variability in what is considered a basaloid salivary gland tumor, one may question the inclusion of certain entities (canalicular adenoma, HMGA2::WIF1 pleomorphic adenoma, polymorphous adenocarcinoma) in this review based on classic morphologic features. However, salivary gland tumors with even minor basaloid components may appear 'basaloid' in small biopsy specimens and, thus, a choice was made to focus on common and uncommon diagnostic differentials with this in mind. Entities that will be covered in this review also include basal cell adenoma and basal cell adenocarcinoma, adenoid cystic carcinoma, lymphoepithelial carcinoma, sialoblastoma, adamantinoma-like Ewing Sarcoma, NUT carcinoma, and carcinoma showing thymus-like differentiation.

Proceedings of the 2024 North American Society of Head and Neck Pathology Companion Meeting, Baltimore, MD, March 24, 2024: Navigating Ancillary Studies in Basaloid/Blue Salivary Tumors

BACKGROUND

Basaloid salivary tumors can demonstrate significant morphologic overlap and be challenging to diagnose.

METHODS

A review of select ancillary studies in basaloid salivary tumors was performed.

RESULTS

A number of immunohistochemical stains, including PLAG1, HMGA2, β-catenin, MYB, and RAS Q61R, have been more recently incorporated into the diagnostic workup of basaloid salivary tumors.

CONCLUSIONS

Although reported variability in their performance has perhaps limited their widespread adoption, these immunohistochemical studies can nevertheless be useful in supporting pathologic diagnoses, particularly when considered in more specific differentials or when used as a panel with other markers.

CYLD induces high oxidative stress and DNA damage through class I HDACs to promote radiosensitivity in nasopharyngeal carcinoma

Abnormal expression of Cylindromatosis (CYLD), a tumor suppressor molecule, plays an important role in tumor development and treatment. In this work, we found that CYLD binds to class I histone deacetylases (HDAC1 and HDAC2) through its N-terminal domain and inhibits HDAC1 activity. RNA sequencing showed that CYLD-HDAC axis regulates cellular antioxidant response via Nrf2 and its target genes. Then we revealed a mechanism that class I HDACs mediate redox abnormalities in CYLD low-expressing tumors. HDACs are central players in the DNA damage signaling. We further confirmed that CYLD regulates radiation-induced DNA damage and repair response through inhibiting class I HDACs. Furthermore, CYLD mediates nasopharyngeal carcinoma cell radiosensitivity through class I HDACs. Thus, we identified the function of the CYLD-HDAC axis in radiotherapy and blocking HDACs by Chidamide can increase the sensitivity of cancer cells and tumors to radiation therapy both in vitro and in vivo. In addition, ChIP and luciferase reporter assays revealed that CYLD could be transcriptionally regulated by zinc finger protein 202 (ZNF202). Our findings offer novel insight into the function of CYLD in tumor and uncover important roles for CYLD-HDAC axis in radiosensitivity, which provide new molecular target and therapeutic strategy for tumor radiotherapy.

The Potential of Cylindromatosis (CYLD) as a Therapeutic Target in Oxidative Stress-Associated Pathologies: A Comprehensive Evaluation

Oxidative stress (OS) arises as a consequence of an imbalance between the formation of reactive oxygen species (ROS) and the capacity of antioxidant defense mechanisms to neutralize them. Excessive ROS production can lead to the damage of critical biomolecules, such as lipids, proteins, and DNA, ultimately contributing to the onset and progression of a multitude of diseases, including atherosclerosis, chronic obstructive pulmonary disease, Alzheimer's disease, and cancer. Cylindromatosis (CYLD), initially identified as a gene linked to familial cylindromatosis, has a well-established and increasingly well-characterized function in tumor inhibition and anti-inflammatory processes. Nevertheless, burgeoning evidence suggests that CYLD, as a conserved deubiquitination enzyme, also plays a pivotal role in various key signaling pathways and is implicated in the pathogenesis of numerous diseases driven by oxidative stress. In this review, we systematically examine the current research on the function and pathogenesis of CYLD in diseases instigated by oxidative stress. Therapeutic interventions targeting CYLD may hold significant promise for the treatment and management of oxidative stress-induced human diseases.

Basal Cell Adenoma and Basal Cell Adenocarcinoma: a 50-year Experience From a Single Institution

BACKGROUND

Basal cell adenoma (BCA) and adenocarcinoma (BCAd) are two of the least frequent salivary gland tumors. We describe the largest series of these neoplasms, spanning over a period of 50 years (1970-2020), diagnosed and treated in a single Institution.

METHODS

Sixty-eight cases were identified. Clinical and pathological data were collected and correlated with outcome.

RESULTS

Forty-one BCA and 27 BCAd were identified. BCA cases had almost pristine prognosis, with only a relapse in a tumor inadequately excised. Ten patients with BCAd developed metastases, and 14 died from the disease. The 2-year and 5-year survival was of 76% and 42%.

CONCLUSIONS

The importance of adequate excision is reinforced in BCA, with no recurrences occurring when margins were negative. Contrary to previous reports, BCAd was not associated with a good prognosis. A better understanding of the genetics of these neoplasms may identify therapeutic options when dealing with inoperable or metastatic disease.

The evolving role of molecular pathology in the diagnosis of salivary gland tumours with potential pitfalls

Salivary gland tumors are diagnostically challenging owing to the morphological diversity within any tumor type and overlapping histomorphology and immunohistochemistry amongst different tumours. In past two decades, rapid progress has been made in the field of understanding the pathogenesis of these tumours with the discovery of many tumour specific translocations and rearrangements. This includes CRTC1-MAML2 and CRTC-MAML2 in mucoepidermoid carcinoma, MYBNFIB and MYBL1-NFIB fusions in adenoid cystic carcinoma, PLAG1 and HMGA2 in pleomorphic adenoma, ETV6-NTRK3 in secretory carcinoma, NR4A3 rearrangements in acinic cell carcinoma, PRKD1 mutations in polymorphous adenocarcinoma and EWSR1-ATF1 in clear cell carcinoma. This review is a lens for progress made till date in the molecular pathology of salivary gland tumours with a special focus on their role as diagnostic tools and implications on clinical management of the patient as prognostic and predictive markers.

Update from the 5th Edition of the World Health Organization Classification of Head and Neck Tumors: Familial Tumor Syndromes

The initiative of the 5th edition of the WHO classification of the Head and Neck Tumours establishing a new section dedicated to familial/heritable tumor syndromes with tumors and lesions in the head and neck region was much needed to better understand the tumours, diseases, and associated syndromes, as well as establish recommendations for monitoring and treating these patients. (WHO Classification of Tumours Editorial Board. Head and Neck tumours. Lyon (France): International Agency for Research on Cancer; 2022. https://publications.iarc.fr/ ). Within the newly established chapter on genetic tumor syndromes, we have described the main manifestations on the head and neck region in 15 syndromes. This review highlights the important findings within these syndromes, especially on the update on syndromes with tumors involving the head and neck region, as Gorlin syndrome/nevoid basal cell carcinoma syndrome associated with odontogenic keratocysts; Brooke-Spiegler syndrome/familial cylindromatosis and the associated membranous-type salivary gland basal cell adenoma, PTEN hamartoma tumor syndrome/Cowden syndrome with associated facial skin and mucosal lesions and characteristic multinodular thyroid lesions, Von Hippel Lindau syndrome and the associated middle ear endolymphatic sac tumor, as well as the fascinating genetic aspects of the diverse Head and Neck Paragangliomas. We will also discuss hyperparathyroidism-jaw tumor syndrome is characterized by parathyroid tumors in association with fibro-osseous jaw tumors, as well as head and neck desmoid tumors associated with familial adenomatous polyposis with Gardner syndrome variant familial, multicentric head and neck squamous cell carcinoma, tuberous sclerosis and neurofibromatosis type 1-associated head and neck lesions.

Development of head and neck pathology in Europe

This review gives a brief history of the development of head and neck pathology in Europe from a humble beginning in the 1930s to the explosive activities the last 15 years. During the decades before the introduction of immunohistochemistry in the 1980s, head and neck pathology grew as a subspeciality in many European countries. In the late 1940s, the Institute of Laryngology and Otology with its own pathology laboratory was founded in London, and in 1964 the World Health Organization (WHO) International Reference Centre for the Histological Classification of Salivary Tumours was established at the Bland-Sutton Institute of Pathology, also in London. International collaboration, and very much so in Europe, led to the publication of the first WHO Classification of Salivary Gland Tumours in 1972. In the 1960s, a salivary gland register was organised in Hamburg and in Cologne the microlaryngoscopy was invented enabling microscopic endoscopic examination and rather shortly afterwards a carbon dioxide laser attached to the microscope became established and laryngeal lesions could be treated by laser vaporisation. During the last three decades, the use of immunohistochemistry supplemented with cytogenetic and refined molecular techniques has greatly facilitated the pathological diagnostics of head and neck lesions and has had a huge impact on research. Collaboration between different European centres has drastically increased partly due to establishment of scientific societies such as the Head and Neck Working Group (HNWG) within the European Society of Pathology and the International Head and Neck Scientific Group (IHNSG). A very large number of European pathologists have contributed to the 2nd, 3rd and 4th WHO books, and are involved in the upcoming 5th edition. Accredited educational meetings and courses are nowadays regularly arranged in Europe. Numerous textbooks on head and neck pathology have been written and edited by European pathologists. The increased collaboration has created larger series of tumours for research and new entities, mainly defined by their genetic abnormalities, are continuously emerging from Europe, particularly regarding salivary gland neoplasms and "undifferentiated" sinonasal tumours. These findings have led to a better and more precise classification and open the possibilities for new treatment strategies.

Practical immunohistochemistry in the classification of salivary gland neoplasms

Diagnosis of salivary gland neoplasms can be challenging for surgical pathologists due to low incidence of tumors as well as overlapping histologic features. On small biopsy, the most important information to be conveyed for clinical management is the distinction between a benign/low grade tumor and a high grade carcinoma. This review will discuss the differential diagnosis of salivary gland tumors based on four broad morphologic patterns: basaloid/tubular/cribriform, (micro)cystic/secretory/mucinous, solid-nested/clear-spindled, and oncocytic/oncocytoid. With the assistance of immunohistochemistry, demonstration of the number of cell types (mainly epithelial versus myoepithelial/basal) can further subclassify tumors within these morphologic categories. Additional tumor-specific immunomarkers are useful in some cases. Underlying tumor-specific genetic anomalies can be of value, however, immunohistochemical correlates are only available for some. When used judiciously, in the correct morphologic context, and with knowledge of their limitations, immunohistochemical stains can aid in differentiating tumors with similar morphology.

TRAF3 and NBR1 both influence the effect of the disease-causing CYLD(Arg936X) mutation on NF-κB activity

Recently described Hungarian and Anglo-Saxon pedigrees that are affected by CYLD cutaneous syndrome (syn: Brooke-Spiegler syndrome (BSS)) carry the same disease-causing mutation (c.2806C>T, p.Arg936X) of the cylindromatosis (CYLD) gene but exhibit striking phenotypic differences. Using whole exome sequencing, missense genetic variants of the TRAF3 and NBR1 genes were identified in the affected family members of the Hungarian pedigree that are not present in the Anglo-Saxon pedigree. This suggested that the affected proteins (TRAF3 and NBR1) are putative phenotype-modifying factors. An in vitro experimental system was set up to clarify how wild type and mutant TRAF3 and NBR1 modify the effect of CYLD on the NF-κB signal transduction pathway. Our study revealed that the combined expression of mutant CYLD(Arg936X) with TRAF3 and NBR1 caused increased NF-κB activity, regardless of the presence or absence of mutations in TRAF3 and NBR1. We concluded that increased expression levels of these proteins further strengthen the effect of the CYLD(Arg936X) mutation on NF-κB activity in HEK293 cells and may explain the phenotype-modifying effect of these genes in CYLD cutaneous syndrome. These results raise the potential that detecting the levels of TRAF3 and NBR1 might help explaining phenotypic differences and prognosis of CCS.

Stabilization of p18 by deubiquitylase CYLD is pivotal for cell cycle progression and viral replication

p18 is a key negative regulator of cell cycle progression and mediates cell cycle arrest at the G1/S phase. Ubiquitination is the prime mechanism in regulating p18 protein abundance. However, so far no post- translational regulator, especially DUBs, has been identified to regulate the protein stability of p18. In this paper, we identified CYLD as a deubiquitinase of p18, which binds to and removes the K48-linked polyubiquitylation chains conjugated onto p18, thus stabilizing the p18 protein. Loss of CYLD causes the degradation of p18 and induces the G1/S transition. Epstein-Barr virus (EBV), is the human oncovirus etiologically linked to nasopharyngeal carcinoma (NPC). Here we found that EBV drives a replication passive environment by deregulating the CYLD-p18 axis. Functionally, CYLD inhibits cell proliferation and tumorigenesis through p18 in vivo. Restoring CYLD prevents EBV induced viral replication and tumor growth. Collectively, our results identify CYLD directly stabilizes p18 to regulate the cellular G1/S transition. The reconstitution of CYLD-p18 axis could be a promising approach for EBV-positive cancer therapy.

Emerging Entities in Salivary Pathology: A Practical Review of Sclerosing Microcystic Adenocarcinoma, Microsecretory Adenocarcinoma, and Secretory Myoepithelial Carcinoma

In recent years, increased molecular testing and improved immunohistochemical panels have facilitated more specific classification of salivary gland carcinomas, leading to recognition of several novel tumor types and unique histologic variants. Sclerosing microcystic adenocarcinoma, microsecretory adenocarcinoma, and secretory myoepithelial carcinoma are three such recently described entities that demonstrate low-grade cytology, production of prominent secretory material, and variable amounts of sclerotic stroma. This review provides a practical overview of these important and overlapping emerging entities in salivary gland pathology with a focus on distinctive histologic features and helpful ancillary studies that differentiate them from a wide range of familiar morphologic mimics.

Molecular Pathology of Salivary Gland Neoplasms: Diagnostic, Prognostic, and Predictive Perspective

Salivary gland neoplasms are an uncommon and widely heterogeneous group of tumors. In recent years, there has been considerable progress in efforts to reveal the molecular landscape of these tumors, although it is still limited and appears to be only the tip of the iceberg. Genomic aberrations, especially specific chromosomal rearrangements including CRTC1-MAML2 and CRTC3-MAML2 in mucoepidermoid carcinoma, MYB-NFIB and MYBL1-NFIB fusions in adenoid cystic carcinoma, PLAG1 and HMGA2 alterations in pleomorphic adenoma and carcinoma ex pleomorphic adenoma, ETV6-NTRK3 and ETV6-RET in secretory carcinoma, EWSR1-ATF1 and EWSR1-CREM in clear cell carcinoma, provide new insights into the molecular pathogenesis of various salivary gland neoplasms and help to better classify them. These genetic aberrations primarily serve as diagnostic tools in salivary gland tumor diagnosis; however, some also have promise as prognostic or predictive biomarkers. This review summarizes the latest developments in molecular pathology of salivary gland tumors with a focus on distinctive molecular characteristics.

Basal Cell Adenoma and Basal Cell Adenocarcinoma

Basal cell adenoma (BCA) and basal cell adenocarcinoma (BCAC) are uncommon biphasic salivary gland tumors having morphologic similarities to other biphasic salivary gland neoplasms having differentiation toward the intercalated ducts of the salivary gland. Both tumors show mixtures of trabecular, tubular, solid, and membranous solid patterns. BCAC is separated from BCA primarily by the presence of invasion in the former. The diagnosis of BCA and BCAC is best carried out with hematoxylin and eosin-stained sections and careful attention to detail of tumors in the differential diagnosis, including adenoid cystic carcinoma, pleomorphic adenoma, and epithelial myoepithelial carcinoma.

CYLD mutation characterizes a subset of HPV-positive head and neck squamous cell carcinomas with distinctive genomics and frequent cylindroma-like histologic features

Mutations in the tumor suppressor CYLD, known to be causative of cylindromas, were recently described in a subset of high-risk (hr) HPV-positive head and neck squamous cell carcinomas (HNSCC). Pathologic and genetic characterization of these CYLD-mutant carcinomas, however, remains limited. Here, we investigated whether CYLD mutations characterize a histopathologically and genomically distinct subset of hrHPV-positive HNSCC. Comprehensive genomic profiling via hybrid capture-based DNA sequencing was performed on 703 consecutive head and neck carcinomas with hrHPV sequences, identifying 148 unique cases (21%) harboring CYLD mutations. Clinical data, pathology reports, and histopathology were reviewed. CYLD mutations included homozygous deletions (n = 61/148; 41%), truncations (n = 52; 35%), missense (n = 26; 18%) and splice-site (n = 9; 6%) mutations, and in-frame deletion (n = 1; 1%). Among hrHPV-positive HNSCC, the CYLD-mutant cohort showed substantially lower tumor mutational burden than CYLD-wildtype cases (n = 555) (median 2.6 vs. 4.4 mut/Mb, p < 0.00001) and less frequent alterations in PIK3CA (11% vs. 34%, p < 0.0001), KMT2D (1% vs. 16%, p < 0.0001), and FBXW7 (3% vs. 11%, p = 0.0018). Male predominance (94% vs. 87%), median age (58 vs. 60 years), and detection of HPV16 (95% vs. 89%) were similar. On available histopathology, 70% of CYLD-mutant HNSCC (98/141 cases) contained hyalinized material, consistent with basement membrane inclusions, within crowded aggregates of tumor cells. Only 7% of CYLD-wildtype cases demonstrated this distinctive pattern (p < 0.0001). Histopathologic patterns of CYLD-mutant HNSCC lacking basement membrane inclusions included nonkeratinizing (n = 22, 16%), predominantly nonkeratinizing (nonkeratinizing SCC with focal maturation; n = 10, 7%), and keratinizing (n = 11, 8%) patterns. The latter two groups showed significantly higher frequency of PTEN alterations compared with other CYLD-mutant cases (38% [8/21] vs. 7% [8/120], p = 0.0004). Within our cohort of hrHPV-positive HNSCCs, CYLD mutations were frequent (21%) and demonstrated distinctive clinical, histopathologic, and genomic features that may inform future study of prognosis and treatment.

CYLD-mutant cylindroma-like basaloid carcinoma of the anus: a genetically and morphologically distinct class of HPV-related anal carcinoma

Rare reports of anal carcinoma (AC) describe histologic resemblance to cutaneous cylindroma, but mutations in the tumor suppressor CYLD, the gene responsible for familial and sporadic cylindromas, have not been systematically investigated in AC. Here, we investigate CYLD-mutant AC, focusing on molecular correlates of distinct histopathology. Comprehensive genomic profiling (hybrid-capture-based DNA sequencing) was performed on 574 ACs, of which 75 unique cases (13%) harbored a CYLD mutation. Clinical data, pathology reports, and histopathology were reviewed for each CYLD-mutant case. The spectrum of CYLD mutations included truncating (n = 50; 67%), homozygous deletion (n = 10; 13%), missense (n = 16; 21%), and splice-site (n = 3; 4%) events. Compared with CYLD-wildtype AC (n = 499), CYLD-mutant ACs were significantly enriched for females (88% vs. 67%, p = 0.0001), slightly younger (median age 59 vs. 61 years, p = 0.047), and included near-universal detection of high-risk HPV sequences (97% vs. 88%, p = 0.014), predominantly HPV16 (96%). The CYLD-mutant cohort also showed significantly lower tumor mutational burden (TMB; median 2.6 vs. 5.2 mut/Mb, p < 0.00001) and less frequent alterations in PIK3CA (13% vs. 31%, p = 0.0015). On histopathologic examination, 73% of CYLD-mutant AC (55/75 cases) showed a striking cylindroma-like histomorphology, composed of aggregates of basaloid cells surrounded by thickened basement membranes and containing characteristic hyaline globules, while only 8% of CYLD-wildtype tumors (n = 34/409) contained cylindroma-like hyaline globules (p < 0.0001). CYLD-mutant carcinomas with cylindroma-like histomorphology (n = 55) showed significantly lower TMB compared with CYLD-mutant cases showing basaloid histology without the distinctive hyaline globules (n = 14) (median 1.7 vs. 4.4 mut/Mb, p = 0.0058). Only five CYLD-mutant cases (7%) showed nonbasaloid conventional squamous cell carcinoma histology (median TMB = 5.2 mut/Mb), and a single CYLD-mutant case showed transitional cell carcinoma-like histology. Within our cohort of ACs, CYLD mutations characterize a surprisingly large subset (13%), with distinct clinical and genomic features and, predominantly, a striking cylindroma-like histopathology, representing a genotype-phenotype correlation which may assist in classification of AC.

Regulation of NFκB Signalling by Ubiquitination: A Potential Therapeutic Target in Head and Neck Squamous Cell Carcinoma?

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide, with over 600,000 cases per year. The primary causes for HNSCC include smoking and alcohol consumption, with an increasing number of cases attributed to infection with Human Papillomavirus (HPV). The treatment options for HNSCC currently include surgery, radiotherapy, and/or platinum-based chemotherapeutics. Cetuximab (targeting EGFR) and Pembrolizumab (targeting PD-1) have been approved for advanced stage, recurrent, and/or metastatic HNSCC. Despite these advances, whilst HPV+ HNSCC has a 3-year overall survival (OS) rate of around 80%, the 3-year OS for HPV- HNSCC is still around 55%. Aberrant signal activation of transcription factor NFκB plays an important role in the pathogenesis and therapeutic resistance of HNSCC. As an important mediator of inflammatory signalling and the immune response to pathogens, the NFκB pathway is tightly regulated to prevent chronic inflammation, a key driver of tumorigenesis. Here, we discuss how NFκB signalling is regulated by the ubiquitin pathway and how this pathway is deregulated in HNSCC. Finally, we discuss the current strategies available to target the ubiquitin pathway and how this may offer a potential therapeutic benefit in HNSCC.

Basal cell adenocarcinoma of the parotid gland: Comparison with basal cell adenoma for preoperative diagnosis

OBJECTIVE

To summarize the diagnosis and treatment outcomes of basal cell adenocarcinoma (BCAC) of the parotid gland, a rare low-grade malignancy, at a single institution, and to investigate the treatment approach for this rare malignancy.

METHODS

We conducted a retrospective analysis of 9 patients with BCAC during 20 years from September 1999 to December 2019. Forty-five patients with basal cell adenoma (BCA), who were treated during the same time period, were used for comparison. The clinical characteristics of BCAC, diagnostic imaging, the usefulness of fine-needle aspiration cytology (FNAC) and frozen section biopsy (FSB), histological assessment of malignancy, and treatment outcomes were investigated.

RESULTS

There were no marked differences in sex, age, tumor diameter, or tumor location between BCAC and BCA cases. Among the 9 patients with BCAC, one patient was noted with pain/tenderness, and two patients were observed with adhesion to the surrounding tissues. Only one patient was diagnosed as malignant based on MRI/US. FNAC for BCAC was suspicious for malignancy in 6 of the 9 cases, which included one patient with the correct grade of malignancy, one patient with malignancy only, and 4 patients suspicious for malignancy. FSB was suspicious for malignancy in 8 of the 9 cases. Malignancy grade was determined based on infiltration to the surrounding tissues and expression of Ki-67, p53, and bcl-2. One patient with infiltration to the surrounding tissue was diagnosed as intermediate-grade malignancy, while the remaining 8 patients were diagnosed as low-grade malignancy. The BCAC cases included 7 patients with T2 and 2 patients with T1. Conservative resection was performed for all patients, and all cases are surviving cancer-free.

CONCLUSION

The malignancy of BCAC can be suspected before surgery based on symptoms/signs, diagnostic imaging, and FNAC. FSB enables the diagnosis of not only malignancy but also the grade of malignancy, which may help determine the appropriate surgical resection. Although all 9 patients with BCAC are surviving free from cancer, a long-term follow-up is warranted.

Navigating small biopsies of salivary gland tumors: a pattern-based approach

Diagnosis of salivary gland tumors on small biopsy can be difficult because of overlapping morphology, limited tissue availability, and technical artifact. Although a specific diagnosis is not feasible in all cases, a cautious and thoughtful approach to the differential diagnosis and a keen awareness of clinical consequences can facilitate the most complete and useful classification possible. In this review, we present a general strategy for the evaluation of small salivary biopsies, including consideration of clinical and radiographic information, systematic assessment of histologic patterns, and judicious use of immunohistochemistry and molecular studies. We then focus on the distinctive differential diagnoses raised by 6 specific histologic patterns: tubular and cribriform architecture, squamous differentiation, mucin and other secretions, high-grade cytology, epithelial and lymphoid elements, and oncocytic features. Throughout this systematic and pattern-based approach, we focus on practical and cost-effective strategies to overcome the most common diagnostic challenges in limited material.

Review of treatment modalities and outcomes of patients with basal cell adenocarcinoma

PURPOSE

This study summarizes the treatment modalities of basal cell adenocarcinoma (BCAC) of the parotid gland and subsequent outcome at a single institution to better define the treatment of this rare tumor.

MATERIAL AND METHODS

A retrospective review of patients treated for BCAC of the parotid gland from 1/01/1996 to 08/1/2018 was performed. Patients were identified using our institution's Cancer Registry.

RESULTS

A total of thirteen patients (46% female, median age of 56) treated for BCAC of the parotid gland were identified. Eight patients (57%) were staged as T1, four were staged as T2 (29%), and two were stage T4a (14%) due to tumor involvement of the facial nerve. None of the patients had nodal involvement or distant metastases. Three patients (21%) underwent radiation therapy ranging from 60-70Gy for positive margin or facial nerve involvement by tumor. Five patients (36%) underwent a neck dissection (ND) ranging from just a level IIb dissection up to levels IIa, IIb, and III with none of the nodes being positive for disease. The remainder of patients did not undergo a neck dissection. Follow-up was 8.1 ± 6.2 (mean ± SD) years with no local or regional recurrence at time of last follow-up in any patient cohort.

CONCLUSIONS

Our review suggests that elective neck dissections are not necessary following resection of T1/T2N0M0 basal cell adenocarcinoma for the prevention of local or regional recurrence. No longer performing neck dissections for T1/T2N0M0 BCAC would reduce the morbidity associated with the treatment of this rare parotid tumor.

An update on head and neck cancer: new entities and their histopathology, molecular background, treatment, and outcome

The head and neck region harbor numerous specialized tissues of all lineages giving rise to a plethora of different malignancies. In recent years, new types and subtypes of cancer has been described here due to the recognition of their histological and molecular characteristics. Some have been formally accepted in the most recent classifications from the World Health Organization (WHO) and American Joint Committee on Cancer (AJCC) as distinct diseases due to characteristics in clinical presentation, outcome, and treatment. In particular, this applies to malignancies of the salivary gland, sinonasal tract, and oropharynx. In this overview, we present the most recent developments in the classification, histopathological characteristics, and molecular features of head and neck cancer. The clinical and radiological characteristics, outcome, and treatment options including perspectives for targeted therapies, are discussed.

Alterations of 63 hub genes during lingual carcinogenesis in C57BL/6J mice

To identify potential biomarkers of lingual cancer, 75 female C57BL/6J mice were subjected to 16-week oral delivery of 4-nitroquinoline-1-oxide (4NQO; 50 mg/L), with 10 mice used as controls. Lingual mucosa samples representative of normal tissue (week 0) and early (week 12) and advanced (week 28) tumorigenesis were harvested for microarray and methylated DNA immunoprecipitation sequencing (MeDIP-Seq). Combined analysis with Short Time-series Expression Miner (STEM), the Cytoscape plugin cytoHubba, and screening of differentially expressed genes enabled identification of 63 hub genes predominantly altered in the early stage rather than the advanced stage. Validation of microarray results was carried out using qRT-PCR. Of 63 human orthologous genes, 35 correlated with human oral squamous cell carcinoma. KEGG analysis showed "pathways in cancer", involving 13 hub genes, as the leading KEGG term. Significant alterations in promoter methylation were confirmed at Tbp, Smad1, Smad4, Pdpk1, Camk2, Atxn3, and Cdh2. HDAC2, TBP, and EP300 scored ≥10 on Maximal Clique Centrality (MCC) in STEM profile 11 and were overexpressed in human tongue cancer samples. However, expression did not correlate with smoking status, tumor differentiation, or overall survival. These results highlight potentially useful candidate biomarkers for lingual cancer prevention, diagnosis, and treatment.