Nuclear β-catenin expression in basal cell adenomas of salivary gland

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.

Infarction of basal cell adenoma of the parotid gland: First case report and literature review on CTNNB1 I35T mutations in salivary basal cell neoplasms

Infarction has rarely been reported in some types of salivary gland tumors. In this study, we present the first case of infarction occurring in salivary basal cell adenoma. A 62-year-old male presented with swelling in the left parotid region. Histopathological examination revealed extensive central necrosis surrounded by a rim of viable tumor tissue showing the typical histology of basal cell adenoma. Nuclear β-catenin expression and the CTNNB1 p.I35T (c.104 T > C) mutation were identified in the tumor. A diagnosis of basal cell adenoma with central necrosis was made, and the postoperative period was uneventful. In addition, we review the literature on CTNNB1 I35T mutations in basal cell neoplasms of the salivary glands. Awareness of the possible occurrence of infarction and the high frequency of the unique mutation in basal cell adenoma may help in the differential diagnosis of salivary gland tumors.

Basal cell adenoma of parotid gland: two case reports and literature review

Most of salivary tumors are benign in nature and are typically diagnosed and classified based on their histopathological presentation. Basal cell adenoma of the salivary glands is a rare, benign disease accounting for 1% to 3% of salivary gland tumors. Despite its low incidence, basal cell adenoma is the third most common benign tumor of the salivary gland after pleomorphic adenoma and Warthin's tumor. It usually appears as a firm and slow-growing mass. Due to the prognosis, differential diagnosis with basal cell adenocarcinoma, adenoid cystic carcinoma and basaloid squamous cell carcinoma is required. In this report, we present two cases; a 62-year-old woman who presented with an asymptomatic, and slow-growing mass and a 64-year-old woman with a static-sized mass in the parotid gland. In both cases, the mass was completely excised, postoperative pathology reports confirmed the diagnosis of basal cell adenoma. We also review the literature and discuss this rare entity.

Immunity-related long noncoding RNA WDFY3-AS2 inhibited cell proliferation and metastasis through Wnt/β-catenin signaling in oral squamous cell carcinoma

OBJECTIVE

Long noncoding RNA WDFY3-AS2 has been shown to play dual roles in the modulation of cancer progression. This study aimed at clarifying the biological role of WDFY3-AS2 as well as the association between WDFY3-AS2 expression, β-catenin expression, and OSCC immunity in oral squamous cell carcinoma (OSCC).

DESIGN

Bioinformatics analyses, CCK8, EdU, wound healing, transwell, RT-qPCR, western blot, immunofluorescence, in situ hybridization, and immunohistochemistry assays were adopted for exploring the role of WDFY3-AS2 in OSCC.

RESULTS

Bioinformatics analyses showed that WDFY3-AS2 conferred a poor prognosis for OSCC patients. Further analyses identified WDFY3-AS2 as an independent prognostic indicator for OSCC. Moreover, silencing WDFY3-AS2 inhibits OSCC cell proliferation, migration and invasion. Gene set enrichment analysis indicated that WDFY3-AS2 participated in the regulation of Wnt signaling. In addition, WDFY3-AS2 expression was positively associated with β-catenin mRNA levels, the key component of Wnt signaling. Interestingly, WDFY3-AS2 knockdown inhibited β-catenin expression and nuclear translocation, thus suppressing OSCC progression through Wnt signaling. Furthermore, WDFY3-AS2 expression correlated with an immunosuppressive phenotype in the tumor immune microenvironment. In situ hybridization and immunohistochemistry verified that WDFY3-AS2 was positively associated with total and nuclear β-catenin protein levels and negatively associated with CD4 expression.

CONCLUSIONS

This study demonstrates that the immunity-associated WDFY3-AS2 augments OSCC proliferation and metastasis through Wnt/β-catenin signaling and may serve as a novel treatment target and a new prognostic factor for OSCC.

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.

Diagnostic role of DOG-1, GFAP and B-catenin in Basal cell Adenoma and Cellular Pleomorphic Adenoma of the Salivary Gland

BACKGROUND

Pleomorphic Adenoma (PA) and Basal cell adenoma (BCA) are benign salivary gland tumors that may pose a diagnostic challenge if typical features are not present. Due to the increased relapse and malignant transformation rate of the former, a correct diagnosis carries relevant prognostic information. Even though immunohistochemistry (IHC) plays a limited role in the diagnosis of these tumors, the use of IHC panels could increase diagnostic accuracy. In the present work, we aimed to demonstrate that the use of an IHC panel consisting of Glial Fibrillary Acid Protein (GFAP), B-Catenin and Discovered On GIST 1 (DOG-1) can aid in the differential diagnosis between PA and BCA.

METHODS

We analyzed 18 cases of benign salivary gland tumors (Pleomorphic adenomas and Basal cell adenomas) with overlapping histologic features. First, a head and neck pathologist diagnosed the cases relying on morphology alone. Afterwards, cases were re-evaluated considering the IHC panel results. Inter-observer IHC scoring concordance was evaluated with pre-defined marker cut-off points using Cohen's Kappa scores.

RESULTS

Based on morphology alone, 9 cases were classified as PA while the remaining tumors were considered to be BCA. Five out of nine BCA cases showed GFAP staining and absent nuclear B-catenin and DOG-1 positivity. Conversely, 2 PA cases showed absent GFAP and positive nuclear B-catenin with concurrent DOG-1 expression. Therefore, after IHC evaluation, up to 40% of morphologic diagnoses were reconsidered. Overall, the inter-observer concordance for IHC evaluation was good (resulting Kappa Scores between 0.78 and 1).

CONCLUSION

Our work supports the use of a concise IHC panel to improve the diagnostic accuracy of benign salivary gland tumors with overlapping histologic features.

A symptomatic intercalated duct lesion of the parotid gland: a case report with immunohistochemical and genetic analyses

Intercalated duct lesions (IDLs) are usually asymptomatic. We report a case of IDL, in which a palpable mass formed. The patient was a 45-year-old Japanese male, who noticed a mass in the left parotid region. The nodular lesion was well-circumscribed, but did not have a fibrous capsule or exhibit infiltrative growth. It contained a small cystic space and consisted of basaloid cells arranged in a cribriform pattern and inner ductal cells. It had some solid areas of nest-like proliferation displaying mild cellular atypia. Immunohistochemically, the luminal cells were positive for cytokeratin (CK)7 and epithelial membrane antigen, and the abluminal cells were positive for CK5/6, p63, and DOG1. S-100 protein-positive stromal cells were also seen. The lesion's cells were all positive for SOX10, and the nuclei of some basaloid cells were positive for β-catenin. The Ki-67 labeling index was 3.8%. The ductal cells contained diastase-digestion-resistant, Periodic acid Schiff-positive zymogen granules. Genetically, the lesion harbored a missense mutation in the CTNNB1 gene. We diagnosed the lesion as an IDL. As IDLs are usually small non-neoplastic lesions, symptomatic cases are rare. Based on its common immunohistochemical and genetic features, IDL may be a precursor of basal cell adenoma/adenocarcinoma, such as intercalated duct adenoma.

A novel parotid carcinoma with a prominent ghost cell population: a masquerading tumor or "salivary ghost cell carcinoma"?

Ghost cell is one of several unique cellular morphologies associated with aberrant keratinization. We encountered a novel parotid tumor containing numerous ghost cells and herein describe its histological features and discuss diagnostic problems. The patient was a 90-year-old Japanese male, who complained of swelling of the left parotid area for four months. Positron emission tomography indicated no cervical lymph node metastasis or distant metastasis. The tumor was successfully resected with no signs of recurrence or metastasis for six months after surgery. Histologically, the tumor was mainly composed of squamous cells forming irregularly shaped nests with a mixture of pleomorphic giant or multinucleated cells and bland basaloid cell. Keratinized areas were occupied by a prominent ghost cell population. Immunohistochemically, CK5/6 and CK19 were widely positive as well as AE1/AE3, p40 and p63. Nuclear expression of β-catenin was also observed. The present case can be regarded as a particular form of squamous cell carcinoma and is believed to contain a large number of ghost cells resulting from an unclear mechanism. However, it seems difficult to consider such tumors as a clinicopathologically independent entity at present. Applying a term such as "salivary ghost cell carcinoma" would be premature.

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.

Epithelial-Myoepithelial Carcinoma

Epithelial-myoepithelial carcinoma is an uncommon low-grade salivary gland carcinoma. It is classically characterized by biphasic tubular structures composed of inner eosinophilic ductal cells and outer clear myoepithelial cells. In addition, epithelial-myoepithelial carcinoma sometimes shows various histologic features, including a cribriform pattern, basaloid appearance, and sebaceous differentiation. Because clear myoepithelial cells are also noted in other benign and malignant salivary gland tumors, the histologic variety and similarity with other tumor entities make the diagnosis of epithelial-myoepithelial carcinoma challenging. A recent analysis revealed that HRAS hotspot point mutations are specifically identified in epithelial-myoepithelial carcinoma and the assessment of given genes facilitate the correct diagnosis.

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.

Human Papillomavirus (HPV)-Related Carcinoma of the Oropharynx with Squamous Cell and Adenoid Cystic Carcinoma-Like Features: Report of a Case

We describe the heretofore unreported case of an HPV-related carcinoma of the palatine tonsil with distinct areas of squamous cell- and adenoid cystic carcinoma-like differentiation in a 54-year old patient. The morphological, immunophenotypic and molecular findings of the tumor are illustrated. We discuss the parallels between the tumor and HPV-related multiphenotypic sinonasal carcinoma (HMSC) which is well-known to exhibit adenoid cystic carcinoma-like features. A review of the literature of high-risk HPV-associated non-squamous carcinomas of the oropharynx is presented.

Salivary duct carcinoma: Updates in histology, cytology, molecular biology, and treatment

Salivary duct carcinoma (SDC) is an aggressive subtype of primary salivary gland carcinoma, often with an advanced stage at presentation and high rates of metastasis and recurrence. It most commonly arises in the parotid gland of older men and microscopically resembles high-grade breast ductal carcinoma. While 50 years have lapsed since the first report of this entity, recent intensive studies have shed light on its biologic, genetic, and clinical characteristics. The diagnosis of SDC is aided by the immunohistochemical expression of androgen receptor (AR) coupled with its characteristic histomorphology. Fine-needle aspiration typically reveals cytologic features of high-grade carcinoma, and ancillary studies using cell block material can facilitate the specific diagnosis of SDC. In surgical specimens, certain histologic features are important prognostic factors, including nuclear pleomorphism, mitotic counts, vascular invasion, and the morphology at the invasion front. Several clinical studies have shown promising results using targeted therapy for AR and human epidermal growth factor receptor 2 (HER2), and the latest version of the National Comprehensive Cancer Network guidelines recommends the evaluation of AR and HER2 status before treatment. Recent molecular analyses have revealed multiple heterogeneous alterations in well-known oncogenes and tumor suppressor genes, including TP53, HRAS, PIK3CA, PTEN, and BRAF. Clinical trials of drugs targeting these genes may broaden the treatment options for SDC in the near future.

Diagnostic Significance of HRAS Mutations in Epithelial-Myoepithelial Carcinomas Exhibiting a Broad Histopathologic Spectrum

Epithelial-myoepithelial carcinoma (EMC) is a rare salivary gland tumor that is histologically characterized by biphasic tubular structures composed of inner ductal and outer clear myoepithelial cells. Because of its histologic variety, it is sometimes challenging to make an accurate diagnosis, and useful ancillary tests are essential for this purpose. We investigated 87 cases of EMC arising in the major and minor salivary glands and seromucinous glands in the nasal cavity or bronchus to describe the histologic features and mutation status of selected key oncogenes. Classic EMC accounted for 40.2% of all cases. Other cases showed various growth patterns and cytologic features in addition to the typical histology; cribriform patterns, a basaloid appearance, and sebaceous differentiation were relatively common (17.2% to 18.4%), whereas oncocytic/apocrine, papillary-cystic, double-clear, squamous, psammomatous, Verocay-like, and high-grade transformation were rare. HRAS mutations were found in 82.7% of EMCs and were concentrated in codon 61. There was no significant correlation between the HRAS mutation status and the histology. No EMC ex pleomorphic adenoma cases had HRAS mutations. PIK3CA and/or AKT1 mutations were the second most frequent mutations (20.7%, 6.5%, respectively) and almost always cooccurred with HRAS mutations. It is noteworthy that the HRAS mutation was not identified in any salivary gland tumor entities manifesting EMC-like features, including adenoid cystic carcinoma, pleomorphic adenoma, basal cell adenoma/adenocarcinoma, and myoepithelial carcinoma. We conclude that HRAS mutations are a frequent tumorigenic gene alteration in EMC, despite its histologic diversity. This study provides further insight into strategies for diagnosing EMC and discriminating it from its mimics.

The HTN3-MSANTD3 Fusion Gene Defines a Subset of Acinic Cell Carcinoma of the Salivary Gland

The spectrum of tumors arising in the salivary glands is wide and has recently been shown to harbor a network of tumor-specific fusion genes. Acinic cell carcinoma (AciCC) is one of the more frequently encountered types of salivary gland carcinoma, but it has remained a genetic orphan until recently when a fusion between the HTN3 and MSANTD3 genes was described in one case. Neither of these 2 genes is known to be implicated in any other malignancy. This study was undertaken to investigate whether the HTN3-MSANTD3 fusion is a recurrent genetic event in AciCC and whether it is a characteristic of one of its histological variants. Of the 273 AciCCs screened, 9 cases showed rearrangement of MSANTD3 by break-apart fluorescence in situ hybridization, 2 had 1 to 2 extra signals, and 1 had gain, giving a total of 4.4% with MSANTD3 aberrations. In 6 of 7 available cases with MSANTD3 rearrangement, the HTN3-MSANTD3 fusion transcript was demonstrated with real-time polymerase chain reaction. Histologically, all fusion-positive cases were predominantly composed of serous tumor cells growing in solid sheets, with serous tumor cells expressing DOG-1 and the intercalated duct-like cell component being CK7 positive and S-100 positive in 6/9 cases. All but one case arose in the parotid gland, and none of the patients experienced a recurrence during follow-up. In contrast, the case with MSANTD3 gain metastasized to the cervical lymph nodes and lungs. In conclusion, we find the HTN3-MSANTD3 gene fusion to be a recurrent event in AciCC with prominent serous differentiation and an indolent clinical course.

Ancillary testing in salivary gland cytology: A practical guide

Salivary gland cytology is challenging, and historically the role of ancillary testing has been limited. However, numerous molecular/genetic advances in the understanding of salivary gland neoplasms during the last decade have facilitated the development of many useful diagnostic markers, such as PLAG1 and HMGA2 immunohistochemistry for pleomorphic adenoma and ETV6 fluorescence in situ hybridization for secretory carcinoma. Numerous salivary gland neoplasms are characterized by specific molecular/genetic alterations, many of which can be identified on cytologic preparations by karyotype analysis, fluorescence in situ hybridization, or immunohistochemical surrogates. Next-generation sequencing also has potential diagnostic applications, although to the authors' knowledge it currently has no routine role in salivary cytology. The primary goal of salivary fine-needle aspiration (FNA) is to facilitate appropriate clinical management. Ancillary testing has greatly enhanced the ability for accurate classification as per The Milan System for Reporting Salivary Gland Cytopathology and allows for the definitive diagnosis of many salivary FNA specimens, and also may resolve diagnostic uncertainty for FNAs that may be classified in The Milan System for Reporting Salivary Gland Cytopathology categories of salivary gland neoplasm of uncertain malignant potential or suspicious for malignancy. This review provides an updated discussion of the molecular/genetic features of the more commonly encountered salivary neoplasms by FNA, and discusses the application of available diagnostic immunohistochemical and molecular tests in salivary gland cytology.

A case of desmoplastic fibroma of bone with CTNNB1 point mutation

Desmoplastic fibroma of bone (DFB), a bone tumor, is considered to be an osseous counterpart of desmoid-type fibromatosis (DF). Herein, we report a case of DFB with CTNNB1 point mutation. The 5-year-old male patient had complained of trismus and pain in the jaw. Magnetic resonance imaging revealed a mass in the left mandible. Radical treatment involved surgical resection. Microscopically, the lesion consisted of a bundle-like proliferation of uniform spindle-shaped cells with abundant collagenous stroma, which resembled DF. Immunohistochemical analysis revealed intranuclear accumulation of β-catenin in the tumor cells. Based on clinical and histologic analysis, we diagnosed the patient as having DFB. We examined the CTNNB1 and APC sequence and found an A-to-G transition at codon 41 of CTNNB1; i.e., Thr was substituted by Ala. Our findings suggest that the dysregulation of Wnt/β-catenin signaling pathway is related to the tumorigenesis of some cases of DFB. This hypothesis indicates that there are some cases of DFB in which nuclear positive expression of β-catenin is useful for diagnosis.

Difference in transducin-like enhancer of split 1 protein expression between basal cell adenomas and basal cell adenocarcinomas - an immunohistochemical study

Background

Basal cell adenoma (BCA) and basal cell adenocarcinoma (BCAC) are benign and malignant, basaloid salivary gland neoplasms, respectively. These tumors show a dual-cell proliferation of inner luminal/ductal cells and outer abluminal/myoepithelial or basal cells. The only difference between them is defined as a malignant morphology such as invasion. Recently, the nuclear expression of β-catenin and a catenin beta-1 (CTNNB1) mutation were found in BCA. Transducin-like enhancer of split 1 (TLE1) belongs to the Groucho/TLE family, and it functions in the “off” state in the Wnt/β-catenin signaling pathway. We hypothesized that if the dysregulation of the Wnt/β-catenin signaling pathway could be attributed to the tumorigenesis of BCA/BCAC, there might be differences in TLE1 expression between BCA and BCAC.

Method

The study included 35 BCA and 4 BCAC cases. We performed immunohistochemistry to detect TLE1 and β-catenin and investigated the catenin beta-1 (CTNNB1) mutational profile among BCA and BCAC cases.

Results

In BCA, the expression of TLE1 was confined to luminal cells of glandular structures, in contrast to the expression of β-catenin in abluminal cells. The BCA cases harbored CTNNB1 gene mutations (12/35). In BCAC, luminal cell staining of TLE1 was identical to BCA in non-invasive areas (4/4) but indistinct in invasive areas (3/4). The BCAC cases were β-catenin positive for abluminal cells in both areas. The BCAC cases had CTNNB1 mutation (2/4) and the laser-captured microdissection allowed the separate collection of infiltrative and non-infiltrative areas to detect the same mutation.

Conclusions

Immunohistochemical analysis for TLE1 can identify BCA and BCAC by luminal cell staining difference, especially indistinct luminal cell expression for TLE1 in invasive areas of BCAC. Moreover, TLE1 can be luminal/ductal cell markers.

Consistent LEF-1 and MYB Immunohistochemical Expression in Human Papillomavirus-Related Multiphenotypic Sinonasal Carcinoma: A Potential Diagnostic Pitfall

Human papillomavirus (HPV)-related multiphenotypic sinonasal carcinoma (HMSC) is a distinct, newly-described sinonasal tract neoplasm characterized by a salivary gland tumor-like appearance with myoepithelial and ductal cells, frequent surface squamous dysplasia, and relatively indolent behavior. When considering a diagnosis of HMSC, aggressive high-grade salivary gland carcinomas, particularly those with a basaloid morphology such as basal cell adenocarcinoma and adenoid cystic carcinoma, enter the differential diagnosis. The full morphologic and immunophenotypic profile of HMSC continues to be unraveled. In this series of ten cases, we demonstrate that this tumor has consistent, strong immunohistochemical expression of LEF-1 yet lacks nuclear expression of β-catenin, and also has consistent yet variable expression of MYB protein. While LEF-1 expression may be a useful diagnostic adjunct, it can also be a pitfall, as other salivary tumors such as basal cell adenocarcinoma have been previously shown to express LEF-1. Additionally, MYB protein expression is not a discriminatory marker when trying to separate HMSC from adenoid cystic carcinoma.

Copy number gain in recurrent anaplastic lymphoma kinase (ALK) rearrangement-lung adenocarcinoma in the pleural effusion

Copy number gain (CNG), which includes both numerical and structural chromosomal abnormalities, has been investigated in many human cancers. We report a case of recurrence of anaplastic lymphoma kinase (ALK) rearrangement-positive lung adenocarcinoma with increased cellular pleomorphism and ALK copy number in pleural effusion cytology, and retrospectively compared the recurrent tumor with the primary tumor in terms of cytological features, immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). The patient was a woman in her 50s who was found to have a 20 × 20 mm sized mass in the lung by chest computed tomography (CT), and was diagnosed with ALK rearrangement-positive lung adenocarcinoma. The patient was administered ALK inhibitors, such as alectinib, however 4 years later dissemination to the pleural effusion was detected. The smear was of high cellularity, and a predominant population of large-sized pleomorphic adenocarcinoma cells with prominent nucleoli was observed. On FISH and IHC using cell block material, ALK rearrangement and ALK protein expression were identified again, along with recurrent ALK adenocarcinoma cells, which were observed to have an increased ALK copy number compared with the primary ALK adenocarcinoma cells. On the other hand, there was no discrepancy in the expression of various biomarkers between the primary and corresponding recurrent tumor. The present case showed a marked difference in cytological findings and CNG between the primary and recurrent tumor, indicating that DNA aneuploidy may be related to morphological change such as transformation to bizarre pleomorphic cells in patients receiving alectinib treatment.

Wnt/β-catenin signal alteration and its diagnostic utility in basal cell adenoma and histologically similar tumors of the salivary gland

Differential diagnosis among basal cell adenoma (BCA), basal cell adenocarcinoma (BCAC), adenoid cystic carcinoma (ACC) and pleomorphic adenoma (PA) of the salivary gland can be challenging due to their similar histological appearance. Although frequent nuclear β-catenin expression and CTNNB1 mutations have been reported in BCA, further details of the Wnt/β-catenin signal alterations are unclear. The aim of this study was to assess the diagnostic utility of Wnt/β-catenin signal alteration in BCA and morphological mimics. We performed immunohistochemical staining for β-catenin and mutation analysis for Wnt/β-catenin-related genes (CTNNB1, APC, AXIN1 and AXIN2) in BCA (n = 34), BCAC (n = 3), ACC (n = 67) and PA (n = 31). We also analyzed ACC-specific MYB and MYBL1 gene rearrangements by fluorescence in situ hybridization (FISH). Nuclear β-catenin expression (≥3%) was present in 32/34 cases (94.1%) of BCA, and the nuclear β-catenin labeling index was significantly higher than in other tumor types (p = < 0.0001). In BCA, we found mutations in CTNNB1, APC and AXIN1 genes (41.1%, 2.9% and 8.8%, respectively). In BCAC, nuclear β-catenin expression with CTNNB1 mutation was present in 1/3 cases (33.3%). As for ACC, nuclear β-catenin expression was observed in 3/67 cases (4.4%), but all 3 cases harbored either MYB or MYBL1 gene rearrangement. The results suggest that nuclear β-catenin immunoreactivity with appropriate criteria may be helpful to distinguish BCA from histologically similar tumors. However, a minor subset of ACCs with nuclear β-catenin expression require careful diagnosis. In addition, Wnt/β-catenin signal alteration may play a role in the pathogenesis of BCA and BCAC.

Distinctive Patterns of CTNNB1 (β-Catenin) Alterations in Salivary Gland Basal Cell Adenoma and Basal Cell Adenocarcinoma

Salivary gland basaloid neoplasms are diagnostically challenging. Limited publications report that some basal cell adenomas harbor CTNNB1 mutations, and nuclear β-catenin expression is prevalent. We evaluated β-catenin expression in basal cell adenomas and adenocarcinomas in comparison with salivary tumors in the differential diagnosis and performed targeted genetic analysis on a subset of cases. β-catenin immunohistochemistry was performed on formalin-fixed, paraffin-embedded whole sections from 73 tumors. Nuclear staining was scored semiquantitatively by extent and intensity. DNA was extracted from 6 formalin-fixed, paraffin-embedded samples (5 basal cell adenomas, 1 basal cell adenocarcinoma) for next-generation sequencing. Nuclear β-catenin staining was present in 18/22 (82%) basal cell adenomas; most were diffuse and strong and predominant in the basal component. Two of 3 basal cell adenocarcinomas were positive (1 moderate focal; 1 moderate multifocal). All adenoid cystic carcinomas (0/20) and pleomorphic adenomas (0/20) were negative; 2/8 epithelial-myoepithelial carcinomas showed focal nuclear staining. Most β-catenin-negative tumors showed diffuse membranous staining in the absence of nuclear staining. Four of 5 basal cell adenomas had exon 3 CTNNB1 mutations, all c.104T>C (p.I35T). Basal cell adenocarcinoma showed a more complex genomic profile, with activating mutations in PIK3CA, biallelic inactivation of NFKBIA, focal CYLD deletion, and without CTNNB1 mutation despite focal β-catenin expression. Nuclear β-catenin expression has moderate sensitivity (82%) for basal cell adenoma but high specificity (96%) in comparison with its morphologic mimics. CTNNB1 mutation was confirmed in most basal cell adenomas tested, and findings in basal cell adenocarcinoma suggest possible tumorigenic mechanisms, including alterations in PI3K and NF-κB pathways and transcriptional regulation.

Basaloid/blue salivary gland tumors

Basaloid tumors are a common diagnostic problem in salivary gland pathology. However, delineating each of these tumor types is facilitated by an algorithmic approach incorporated by tumor border and cell types. This approach greatly diminishes the challenge of separating polymorphous low-grade adenocarcinoma (PLGA) from adenoid cystic carcinoma (ACC). Despite the overlap in growth pattern, ACC is biphasic while PLGA is not. More relevant challenges, namely differentiation of the biphasic basaloid neoplasms including: epithelial-myoepithelial carcinoma (EMCA), cellular pleomorphic adenoma (PA), basal cell adenoma (BCA), and basal cell adenocarcinoma (BCAC), are resolved by a combination of morphologic, immunophenotypic, and to a limited extent, molecular features. Among the most challenging scenarios is high-grade transformation of any of the aforementioned entities. Here, the diagnosis requires recognition of a conventional component and exclusion of metastatic (or in some cases primary) SCC and even select neuroendocrine carcinomas and sarcomas in some cases.

Next-Generation Sequencing in Salivary Gland Basal Cell Adenocarcinoma and Basal Cell Adenoma

Basal cell adenoma and basal cell adenocarcinoma represent basaloid salivary gland neoplasms that show cyto-morphologic similarity but differ at the histologic level by their invasive qualities, as adenocarcinomas show invasion beyond their capsule, a finding not seen in the adenomas. Due to the low incidence of these tumors, the molecular mechanism underlying their pathogenesis is poorly understood. We sought to further delineate these neoplasms through mutation profiling by targeted next-generation sequencing (NGS). Twenty cases (basal cell adenocarcinoma = 10; basal cell adenoma = 10) were retrospectively selected from a previous analysis. NGS was performed using the Ion AmpliSeq™ Cancer Hotspot Panel v2 (Life Technologies, Carlsbad, CA). The data was analyzed using the Ion Torrent Suite Software (Life Technologies) followed by a laboratory-developed pipeline. One of eight cases of basal cell adenocarcinoma had a mutation, which was an activating mutation in PIK3CA (c.3140A>G, p.H1047R). No mutations were detected in the remaining basal cell adenocarcinomas. In the basal cell adenomas, the CTNNB1 p.I35T mutation was identified in three of nine (3/9) cases. A missense mutation in the ATM gene (c.2572T>C, p.F858L) was seen in a basal cell adenoma with an allele frequency of 53 %, raising the possibility of a germline mutation. The overall findings suggest that although there is cytomorphologic similarity, differences exist between these two tumors at the histologic and genetic level. Although the numbers of cases are limited, the aberrations in genes affecting different signaling pathways in the basal cell adenocarcinoma versus the basal cell adenomas suggest that basal cell adenocarcinoma likely arises de novo and not from basal cell adenoma.

Beta-catenin in disease

In continuation with the previous review on “β-catenin in health”, in this review we discuss the role of β-catenin in the pathogenesis of common oral lesions in the oral and maxillofacial region- oral potentially malignant disorders, their progression to oral squamous cell carcinoma, salivary gland tumors and odontogenic tumours. This review is based on a pubmed search of all the lesions included in the review.

Molecular Pathology: Predictive, Prognostic, and Diagnostic Markers in Salivary Gland Tumors

Although initial attempts at using ancillary studies in salivary gland tumor classification were viewed with skepticism, numerous advances over the past decade have established a role for assessment of molecular alterations in the diagnosis and potential prognosis and treatment of salivary gland tumors. Many monomorphic salivary tumors are now known to harbor defining molecular alterations, usually translocations. Pleomorphic, high-grade carcinomas tend to have complex alterations that are often further limited by inaccuracy of initial classification by morphologic and immunophenotypic features. Next-generation sequencing techniques have great potential in many aspects of salivary gland tumor classification and biomarker discovery.

Nuclear β-Catenin Expression is Frequent in Sinonasal Hemangiopericytoma and Its Mimics

Sinonasal hemangiopericytoma (HPC) is a tumor showing pericytic myoid differentiation and which arises in the nasal cavity and paranasal sinuses. CTNNB1 mutations appear to be a consistent aberration in sinonasal HPC, and nuclear expression of β-catenin has been reported. Our aim was to evaluate the frequency of β-catenin expression in sinonasal HPC and its histologic mimics in the upper aerodigestive tract. Cases were retrieved from the surgical pathology and consultation files. Immunohistochemical staining for β-catenin was performed on 50 soft tissue tumors arising in the sinonasal tract or oral cavity, and nuclear staining was recorded semiquantitatively by extent and intensity. Nuclear reactivity for β-catenin was present in 19/20 cases of sinonasal HPC; 17 showed moderate-to-strong multifocal or diffuse staining, and 2 had moderate focal nuclear reactivity. All solitary fibrous tumors (SFT) (10/10) showed focal-to-multifocal nuclear staining, varying from weak to strong in intensity. Most cases of synovial sarcoma (9/10) showed nuclear β-catenin expression in the spindle cell component, ranging from focal-weak to strong-multifocal. No cases of myopericytoma (0/10) showed any nuclear β-catenin expression. β-catenin expression is prevalent in sinonasal HPC, but is also frequent in SFT and synovial sarcoma. Our findings indicate that β-catenin is not a useful diagnostic tool in the evaluation of spindle cell tumors with a prominent hemangiopericytoma-like vasculature in the sinonasal tract and oral cavity, and that definitive diagnosis relies on the use of a broader immunohistochemical panel.

Epithelial-Mesenchymal Transition Protein Expression in Basal Cell Adenomas and Basal Cell Adenocarcinomas

Basal cell adenomas and basal cell adenocarcinomas show marked histomorphologic similarity and are separated microscopically primarily by the invasive characteristics of the adenocarcinomas. We wished to explore potential differences in the expression of epithelial-mesenchymal transition associated proteins in these two tumor types. A tissue microarray was constructed utilizing 29 basal cell adenomas and 16 basal cell adenocarcinomas. Immunohistochemical expression of E-cadherin, beta-catenin, Twist 1 and vimentin were investigated. Both tumors expressed all proteins in a relatively similar manner. Nuclear beta-catenin was essentially limited to the abluminal cell populations in both tumor types. E-cadherin was limited largely to luminal locations but was more prevalent in the adenocarcinomas as compared to the adenomas. Primarily abluminal expression for vimentin was seen, sometimes present in an apical dot-like pattern. Distinct populations of cellular expression of these four markers of epithelial mesenchymal transition were present but were similar in locations in both tumors with no patterns discerned to separate basal cell adenoma from basal cell adenocarcinoma. Given these findings, the mechanisms by which basal cell adenocarcinoma is able to invade while its counterpart, basal cell adenoma can not, may be more complex than in other tumor types.

Correlation of β-catenin, but not PIN1 and cyclin D1, overexpression with disease-free and overall survival in patients with cancer of the parotid gland

BACKGROUND

Malignant tumors of the salivary glands comprise about 3% to 5% of all head and neck carcinomas. The purpose of our study was to find possible predictive and/or prognostic markers for parotid cancer.

METHODS

A total of 46 tissue samples of carcinomas of the parotid gland were immunohistochemically stained for ß-catenin, cyclin D1, and PIN1. The factors were analyzed regarding their prognostic value for disease-free and overall survival.

RESULTS

An overexpression of the cytoplasmatic ß-catenin was linked to a statistically significant worse outcome regarding disease-free (p = .0296) and overall survival (p = .0416). The 5-year overall survival was 83.9% in patients without and 0% in patients presenting with overexpression of cytoplasmatic ß-catenin. Additionally, Union Internationale Contre le Cancer (UICC) stage correlated with overall survival (p = .0306) and disease-free survival (DFS; p = .0473).

CONCLUSION

Multivariate analysis showed that overexpression of cytoplasmatic ß-catenin and the UICC stage are 2 independent prognostic markers for survival in patients with parotid cancer.

Basal cell adenocarcinoma of the salivary gland: a morphological and immunohistochemical comparison with basal cell adenoma with and without capsular invasion

Background

It is often difficult to diagnose salivary gland tumors that exhibit basaloid features differentially. The aim of this study was to identify additional morphological and immunohistochemical characteristics that can aid the diagnosis of basal cell adenocarcinoma (BCAC) of the salivary gland.

Methods and results

In total, 29 basal cell neoplasms [eight BCACs, 11 basal cell adenomas (BCAs) with capsular invasion, and 10 BCAs without capsular invasion] and 10 cases of adenoid cystic carcinomas (ACCs) were subjected to histopathology and immunohistochemical analyses for CK7, CK5/6, SMA, p63, calponin, p53, c-erbB2, CD117, β-catenin, EGFR, VEGF, Ki-67, and S100P protein expression. Compared to BCA without capsular invasion, the BCACs and BCAs with capsular invasion were more likely to be larger and have solid or cribriform patterns. Most BCACs and BCAs exhibited nuclear β-catenin expression. In all basal cell neoplasm cases, the clinical course after surgery with or without radiotherapy was indolent. β-catenin, CK5/6, CD117, and S100P protein were helpful for differentiating basal cell neoplasms from ACC.

Conclusions

BCAs with capsular invasion shared several pathological features with BCACs, including a large size and frequent cribriform patterns but the malignant potential of these tumors seems highly limited and should be reexamined. β-catenin immunostaining may aid the differential diagnosis between basal cell neoplasms and ACCs.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/9637819101988153

Rare Malignant and Benign Salivary Gland Epithelial Tumors

Although at least 24 distinct histologic salivary gland carcinomas exist, many of them are rare, comprising only 1% to 2% of all salivary gland tumors. These include epithelial-myoepithelial carcinoma, (hyalinizing) clear cell carcinoma, basal cell adenocarcinoma, cystadenocarcinoma, low-grade salivary duct carcinoma (low-grade cribriform cystadenocarcinoma), oncocytic carcinoma, and adenocarcinoma not otherwise specified. Few tumors (clear cell carcinoma and basal cell adenocarcinoma) have unique molecular correlates. Benign tumors, although histologically less diverse, are far more common, with pleomorphic adenoma and Warthin tumor the most common salivary gland tumors. Many benign tumors have malignant counterparts for which histologic distinction can pose diagnostic challenge.