Pathological evaluation of tumor grade for salivary adenoid cystic carcinoma: A proposal of an objective grading system

Submandibular and sublingual salivary gland involvement in adenoid cystic carcinoma

Adenoid cystic carcinoma (AdCC) is a malignant salivary gland neoplasm that presents as an indolent but aggressive neoplasm. AdCC histogenesis is linked to the intercalated ducts of the salivary glands, equally affecting the major and minor glands. AdCC is associated with distant metastasis, most commonly to the lungs, and a high recurrence rate. AdCC accounts for 4.2% of all tumors. About 55% of all reported cases affect the submandibular gland, and around 50% of AdCC cases occur in the minor salivary glands. The present review describes a case of AdCC which presented a single nodular swelling on the right side involving the floor of the mouth. It also consolidates the histopathological profile of a case of AdCC with all the relevant histopathological features.

Adenoid Cystic carcinoma of minor salivary glands (AdCCmSG): a multidisciplinary update

INTRODUCTION

Adenoid cystic carcinoma of minor salivary glands (AdCCmSG) represents a 'rarity in the rarity,' posing a clinical challenge in lack of standardized, evidence-based recommendations. At present, AdCCmSG management is mostly translated from major salivary gland cancers (MSGCs). Ideally, AdCCmSG diagnostic-therapeutic workup should be discussed and carried out within a multidisciplinary, high-expertise setting, including pathologists, surgeons, radiation oncologists and medical oncologists.

AREAS COVERED

The present review provides an overview of epidemiology and pathologic classification. Moreover, the most recent, clinically relevant updates in the treatment of AdCCmSG (Pubmed searches, specific guidelines) are critically discussed, aiming to a better understanding of this rare pathologic entity, potentially optimizing the care process, and offering a starting point for reflection on future therapeutic developments.

EXPERT OPINION

The management of rare cancers is often hindered by limited data and clinical trials, lack of evidence-based guidelines, and hardly represented disease heterogeneity, which cannot be successfully tackled with a 'one-size-fits-all' approach. Our goal is to address these potential pitfalls, providing an easy-to-use, updated, multidisciplinary collection of expert opinions concerning AdCCmSG management as of today's clinical practice. We will also cover the most promising future perspectives, based on the potential therapeutic targets highlighted within AdCCmSG's molecular background.

Primary and Recurrent Intraosseous Adenoid Cystic Carcinoma-Analysis of Two Cases and Literature Review

Adenoid cystic carcinoma (ACC) is a rare malignant tumor that mostly occurs in minor glands, especially in the palate. Intraosseous adenoid cystic carcinoma (IACC) is rarer. There is no clear conclusion on the clinical, radiologic and pathological characteristics of IACC because of few reported IACC cases, leading to insufficient understanding of IACC. We reviewed 52 previous reports of primary IACC (PIACC) and analyzed the clinical features of those patients involved, attempting to provide a better understanding of PIACC. Moreover, we present a case of primary PIACC and a case of recurrent IACC (RIACC). The two patients showed similarities in clinical and pathological results, along with slight differences in radiological and immunohistochemical results. The patient of case 1 seemed to display a worse prognosis, which can only be proved after long term follow-up.

Evaluation of cell proliferation marker CDC-7 in salivary adenoid cystic carcinoma

BACKGROUND

Adenoid cystic carcinoma (AdCC) is considered one of the most common destructive types of malignant salivary gland tumor that have high affinity to perineural invasion (PNI). This study was conducted to access different histological features of AdCC, and assessment of the immunohistochemical expression of CDC-7.

METHODS

Thirty formalin-fixed paraffin incorporated tissue blocks of AdCC were classified according to the WHO histopathological types. The immune-expression of CDC-7 positive area was evaluated according to percentage area as following: Negative = 0 %, Weak = 1-10 %, Moderate = 11-49 %, and Strong = 50-100. The correlations between expression of the marker and different clinico-pathological variables were investigated using Chi-square (χ2) test. The P-value ≤ 0.05 was considered statistically significant.

RESULTS

The expression of CDC-7 revealed statistical significant difference between the different tumor types (p ≤ 0.05).

CONCLUSION

The biological behavior of AdCC can be predicated from the expression of CDC-7.

Prognostic Significance of Histopathological Parameters for Salivary Gland Adenoid Cystic Carcinoma

Adenoid cystic carcinoma (ACC) is a rare salivary gland tumor that accounts for approximately 1% of all head and neck cancers. Despite its initial indolent behavior, long-term survival is poor due to locoregional recurrence in approximately 40% and distant metastasis in up to 60% of patients who undergo radical treatment. The histological parameters of ACC and the combination of these parameters in histopathological grading systems provide valuable prognostic information about the clinical course of the disease. Within this context, this review aims to analyze the impact of histopathological parameters, individual or combined in histopathological grading systems of malignancy, on ACC prognosis. Individual histopathological parameters such as solid pattern, presence of tumor necrosis, high-grade transformation, dominance of the epithelial component, presence of perineural and lymphovascular invasion, and positive surgical margins have negative impacts on the survival of patients with ACC. There are currently four histopathological grading systems for ACC; however, few studies have validated these systems and most of them explored small cohorts with short follow-up. Considering that the application of grading systems has been associated with ACC prognosis, a broader validation will allow not only their use for prognostic prediction but also assist in treatment planning.

The Landscape of MYB/MYBL1- and Peri-MYB/MYBL1-Associated Rearrangements in Adenoid Cystic Carcinoma

Approximately 60% of adenoid cystic carcinoma (AdCC) cases are positive for MYB::NFIB or MYBL1::NFIB, whereas MYB/MYBL1 oncoprotein, a key driver of AdCC, is overexpressed in most cases. Juxtaposition of superenhancer regions in NFIB and other genes into the MYB/MYBL1 locus is an attractive oncogenic hypothesis for AdCC cases, either negative or positive for MYB/MYBL1::NFIB. However, evidence supporting this hypothesis is insufficient. We examined 160 salivary AdCC cases for rearrangements in MYB/MYBL1 loci and peri-MYB/MYBL1 areas (centromeric and telomeric areas of 10 Mb each) using formalin-fixed, paraffin-embedded tumor sections. For the detection of the rearrangements, we employed conventional fluorescence in situ hybridization split and fusion assays and a 5 Mb fluorescence in situ hybridization split assay. The latter is a novel assay that enabled us to detect any possible splits within a 5 Mb distance of a chromosome. We found MYB/MYBL1- and peri-MYB/MYBL1-associated rearrangements in 149/160 patients (93%). AdCC cases positive for rearrangements in MYB, MYBL1, the peri-MYB area, and the peri-MYBL1 area numbered 105 (66%), 20 (13%), 19 (12%), and 5 (3%), respectively. In 24 peri-MYB/MYBL1 rearrangement-positive cases, 14 (58%) were found to have a juxtaposition of the NFIB or RAD51B locus into the MYB/MYBL1 loci. On comparing with a tumor group positive for MYB::NFIB, a hallmark of AdCC, other genetically classified tumor groups had similar features of overexpression of the MYB transcript and MYB oncoprotein as detected by semiquantitative RT-qPCR and immunohistochemistry, respectively. In addition, clinicopathological and prognostic features were similar among these groups. Our study suggests that peri-MYB/MYBL1 rearrangements may be a frequent event in AdCC and may result in biological and clinicopathological consequences comparable to MYB/MYBL1 rearrangements. The landscape of MYB/MYBL1 and peri-MYB/MYBL1 rearrangements shown here strongly suggests that juxtaposition of superenhancers into MYB/MYBL1 or peri-MYB/MYBL1 loci is an alteration that acts as a key driver for AdCC oncogenesis and may unify MYB/MYBL1 rearrangement-positive and negative cases.

Prognostic scores for patients with salivary adenoid cystic carcinoma without lymph node metastasis

Adenoid cystic carcinoma (AdCC) of salivary gland grows relatively slowly, but occasionally develops distant metastasis. Although cervical lymph node metastasis (LNM) has been reported as a strong prognostic factor, most of AdCC do not have LNM. In this study, we investigated the prognostic factors to predict disease free survival (DFS), distant metastasis free survival (DMFS), and overall survival (OS) for 175 patients surgically treated for AdCC without LNM, and developed prognostic score (PS) determined as number of positive prognostic factors. The following emerged as significant prognostic factors: positive surgical margin in DFS, pT3/4 and positive surgical margin in DMFS, and positive surgical margin and high-histological grade in OS. 10-year DFS rates were 56.4% in PS0, and 19.1% in PS1 (p < 0.0001). 10-year DMFS rates were 86.3% in PS0, 56.4% in PS1, and 30.7% in PS2 (p < 0.0001). 10-year OS rates were 100% in PS0, 73.3% in PS1, and 38.8% in PS2 (p < 0.0001).

Salivary Gland-like Tumors of the Breast

CONTEXT

The World Health Organization classification of tumors of the breast recognizes several special type carcinomas and benign lesions with features comparable to those of salivary gland tumors.

OBJECTIVE

To discuss the histologic, immunophenotypic, molecular, and clinical features of salivary gland-like carcinomas of the breast. These breast tumors are often negative for hormone receptors and human epidermal growth factor receptor 2 (HER2), that is, triple-negative, but they generally have a much better prognosis than triple-negative breast carcinomas of no special type. We compare the immunophenotypic, molecular, and clinical features of these breast tumors with their salivary gland counterparts, highlighting similarities and differences. We also discuss benign salivary gland-like breast tumors. Finally, we highlight recent developments in understanding the molecular pathogenesis of these breast tumors and novel ancillary studies that can be used to support their diagnosis.

DATA SOURCES

A literature review was conducted, and papers were selected for further analysis and discussion by the authors of this review based on their novelty, applicability, and impact in the field.

CONCLUSIONS

Breast tumors that exhibit morphologic overlap with salivary gland tumors have been recognized by pathologists for decades, but the similarities and differences in their molecular pathogenesis have not been understood until more recently. These developments have led to novel diagnostic tools and further knowledge of these rare breast lesions.

Management and outcome of adenoid cystic carcinoma of the major salivary glands: the 22-year experience of a single institution

BACKGROUND

Prognostic factors and survival rate are difficult to determine for adenoid cystic carcinoma(AdCC) of salivary glands.

AIMS/OBJECTIVES

To clarify the clinical characteristics of AdCC and examine factors associated with recurrence and prognosis by histopathological grade classification.

MATERIALS AND METHODS

Twenty-five patients with AdCC of the parotid gland and 10 patients with AdCC of the submandibular gland were included. We classified AdCC histopathologically by the proportion of solid components. Clinical features, fine-needle aspiration cytology (FNAC), and patient outcomes were examined according to grade. Factors associated with local recurrence and distant metastases were examined.

RESULTS

Age was significantly higher in the grade III group than in the grade I group. The grade III group had significantly higher proportions of patients with cN+, pN+, and perineural invasion. In FNAC, lower-grade groups showed higher rates of correct histopathological type. Five-year disease-specific survival and disease-free survival rates were significantly lower in the grade III than in the grade I. Distant metastases were more common among patients with high-stage and perineural invasion.

CONCLUSIONS

Five-year survival is significantly worse in patients with grade III.

Top 10 Basaloid Neoplasms of the Sinonasal Tract

BACKGROUND

Basaloid neoplasms of the sinonasal tract represent a significant group of tumors with histological overlap but often with different etiologies (i.e., viral, genetics), clinical management, and prognostic significance.

METHODS

Review.

RESULTS

"Basaloid" generally refers to cells with coarse chromatin in round nuclei and sparse cytoplasm, resembling cells of epithelial basal layers or imparting an "immature" appearance. Tumors with this characteristic in the sinonasal tract are represented by a spectrum of benign to high-grade malignant neoplasms, such as adenoid cystic carcinoma, NUT carcinoma, sinonasal undifferentiated carcinoma, SWI/SNF complex-deficient carcinomas, and adamantinoma-like Ewing sarcoma.

CONCLUSION

In some instances, histology alone may be sufficient for diagnosis. However, limited biopsy material or fine-needle aspiration specimens may be particularly challenging. Therefore, often other diagnostic procedures, including a combination of histology, immunohistochemistry (IHC), DNA and RNA testing, and molecular genetics are necessary to establish an accurate diagnosis.

Dominant Gene Expression Profiles Define Adenoid Cystic Carcinoma (ACC) from Different Tissues: Validation of a Gene Signature Classifier for Poor Survival in Salivary Gland ACC

Adenoid cystic carcinoma (ACC) is an aggressive malignancy that most often arises in salivary or lacrimal glands but can also occur in other tissues. We used optimized RNA-sequencing to analyze the transcriptomes of 113 ACC tumor samples from salivary gland, lacrimal gland, breast or skin. ACC tumors from different organs displayed remarkedly similar transcription profiles, and most harbored translocations in the MYB or MYBL1 genes, which encode oncogenic transcription factors that may induce dramatic genetic and epigenetic changes leading to a dominant 'ACC phenotype'. Further analysis of the 56 salivary gland ACC tumors led to the identification of three distinct groups of patients, based on gene expression profiles, including one group with worse survival. We tested whether this new cohort could be used to validate a biomarker developed previously with a different set of 68 ACC tumor samples. Indeed, a 49-gene classifier developed with the earlier cohort correctly identified 98% of the poor survival patients from the new set, and a 14-gene classifier was almost as accurate. These validated biomarkers form a platform to identify and stratify high-risk ACC patients into clinical trials of targeted therapies for sustained clinical response.

Histopathological Aspects of the Prognostic Factors for Salivary Gland Cancers

Salivary gland cancers (SGCs) are diagnosed using histopathological examination, which significantly contributes to their progression, including lymph node/distant metastasis or local recurrence. In the current World Health Organization (WHO) Classification of Head and Neck Tumors: Salivary Glands (5th edition), malignant and benign epithelial tumors are classified into 21 and 15 tumor types, respectively. All malignant tumors have the potential for lymph node/distant metastasis or local recurrence. In particular, mucoepidermoid carcinoma (MEC), adenoid cystic carcinoma (AdCC), salivary duct carcinoma, salivary carcinoma, not otherwise specified (NOS, formerly known as adenocarcinoma, NOS), myoepithelial carcinoma, epithelial-myoepithelial carcinoma, and carcinoma ex pleomorphic adenoma (PA) are relatively prevalent. High-grade transformation is an important aspect of tumor progression in SGCs. MEC, AdCC, salivary carcinoma, and NOS have a distinct grading system; however, a universal histological grading system for SGCs has not yet been recommended. Conversely, PA is considered benign; nonetheless, it should be cautiously treated to avoid the development of metastasizing/recurrent PA. The aim of this review is to describe the current histopathological aspects of the prognostic factors for SGCs and discuss the genes or molecules used as diagnostic tools that might have treatment target potential in the future.

Polar Vessel: A New Ultrasound Sign for Complementary Diagnosis of Major Salivary Gland Adenoid Cystic Carcinoma

OBJECTIVES

To investigate the characteristic ultrasonographic findings of adenoid cystic carcinoma (ACC) in major salivary glands and identify the value of polar vessel in color Doppler flow imaging (CDFI) for the diagnosis of ACC.

METHODS

From January 2017 to December 2021, 76 patients with parotid and submandibular gland tumors, including 14 patients with ACC, as confirmed by surgery and histopathology, were enrolled. Their clinicopathologic information and ultrasound (US) features were recorded and analyzed. The performance of polar vessel in CDFI for differentiating ACC from non-ACC (benign tumors and mucoepidermoid carcinoma [MEC]) was analyzed.

RESULTS

ACC in the major salivary gland was more likely to be associated with pain symptoms (P = .027) and unclear borders and rough edges in grayscale US (P = .002, .015, respectively) than benign tumors. Compared to MEC, ACC tended to feature a homogeneous internal echo (P = .008). ACC of the major salivary gland had a significantly higher incidence of polar vessel sign than that of non-ACC (benign tumors and MEC) (P < .0001, .0001, respectively). The polar vessel sign showed good performance in distinguishing between ACC and non-ACC, with an area under the receiver operating characteristic curve of 0.857, a sensitivity of 71.4%, a specificity of 100%, and an accuracy of 94.7%. Positive predictive value and negative predictive value were calculated at 100% and 93.9%, respectively.

CONCLUSIONS

The US sign of polar vessel has high diagnostic efficiency, and it may have important potential for use as a new complementary sign for the diagnosis of ACC in major salivary glands.

Adenoid Cystic Carcinoma of Salivary Glands: A Ten-Year Review and an Assessment of the Current Management, Surgery, Radiotherapy, and Chemotherapy

Adenoid cystic carcinoma (ACC) is a rare cancer that arises from the salivary glands and other sites in the body, such as the lung and breast. Although the tumor accounts for 10% of all salivary gland malignancies, it only accounts for 1% of head and neck malignancies. It can affect both major and minor salivary glands; here, it is called salivary gland adenoid cystic carcinoma or SACC, with a slight predilection to the latter, and commonly manifests between the 6_th and 7_th decades of life. The disease also shows a slight female predilection, with a reported female to male ratio of 3 : 2. Lesions of SACC are often insidious and slow-growing, and symptoms such as pain and altered sensation are frequently associated with advanced stages of the disease. Salivary adenoid cystic carcinoma is characterized by perineural invasion (PNI), a distinctive feature that potentially plays a significant role in the tumor's relapse and recurrence, which is approximately 50%. The disease is not prevalent, and its etiopathogenesis is poorly understood, although several genetic patterns and biomarkers have been linked to its initiation and/or progression. The discovery of these mutations and biomarkers has encouraged several clinical studies to use therapeutic agents to target the specific receptors on the cancer cells to potentially prevent further proliferation of the tumor cells and metastasis of the disease. Diagnosis of SACC is often challenging and frequently requires a combination of clinical examination, imaging, and histopathology. Management of SACC is primarily surgical excision, while radiotherapy has shown to be effective in improving local control in cases with microscopic residual disease. However, treatment of recurrent or metastatic tumors by radiotherapy with or without chemotherapy has so far shown limited success. The aim of this thesis is to provide an update of literature on SACC with a particular focus on the latest management approaches and future trends.

CCL25/CCR9 interaction promotes the malignant behavior of salivary adenoid cystic carcinoma via the PI3K/AKT signaling pathway

Background

CC chemokine receptor 9 (CCR9), an organ-specific chemokine receptor, interacts with its exclusive ligand CCL25 to promote tumor proliferation and metastasis. However, the effect of CCR9 on salivary adenoid cystic carcinoma (SACC) malignant behavior remains unknown. This study aimed to investigate the specific molecular mechanism by which CCR9/CCL25 modulates malignant progression in SACC.

Methods

Immunohistochemistry staining and RT-qPCR analyses were performed to detect the correlation of CCR9 expression and tumor progression-associated markers in SACC. In vitro, SACC cell proliferation and apoptosis were evaluated using Cell Counting Kit-8 and colon formation, and cell migration and invasion were detected by wound healing and transwell assays. Vercirnon was used as an inhibitor of CCR9, and LY294002 was used as an inhibitor of the PI3K/AKT pathway in this study. Western blot and RT-qPCR assays were carried out to measure the downstream factors of the interaction of CCL25 and CCR9. The effect of CCL25 on the development of SACC in vivo was examined by a xenograft tumor model in nude mice following CCL25, Vercirnon and LY294002 treatment.

Results

CCR9 was highly expressed in SACC compared with adjacent salivary gland tissues, and its level was associated with tumor proliferation and metastases. CCL25 enhanced cell proliferation, migration, and invasion through its interaction with CCR9 and exerted an antiapoptotic effect on SACC cells. Targeting CCR9 via Vercirnon significantly reduced the phosphorylation level of AKT induced by CCL25. CCL25/CCR9 could activate its downstream factors through the PI3K/AKT signaling pathway, such as cyclin D1, BCL2 and SLUG, thus promoting SACC cell proliferation, antiapoptosis, invasion and metastasis. The in vivo data from the xenograft mouse models further proved that CCL25 administration promoted malignant tumor progression by activating the PI3K/AKT pathway.

Conclusion

The interaction of CCL25 and CCR9 promotes tumor growth and metastasis in SACC by activating the PI3K/AKT signaling pathway, offering a promising strategy for SACC treatment.

Genetic heterogeneity and therapeutic target detection through microdissection in solid-type adenoid cystic carcinoma

Solid-type adenoid cystic carcinomas (ACCs) are highly aggressive and heterogeneous tumours. Because of their rarity, therapeutic strategies guided by genetic profiles based on next generation sequencing (NGS) have not been published for these tumours. Forty-nine solid-type ACCs including 43 tumours with a predominantly solid pattern, and six tumours comprising a roughly equal mixture of cribriform/tubular and solid histological forms were included in our study. The solid components from the 49 solid ACCs were enriched for mutations of genes in the NOTCH pathway (NOTCH1 61%, SPEN 24%) and chromatin remodelling pathway and the absence of myoepithelial cell differentiation. Cases with NOTCH1 mutations exhibited strong NICD expression, which was associated with poor overall and distant metastasis free survival. BRCA2 mutation and BCOR/BCORL1 mutations were observed in 20% and 18.4% of solid ACCs, respectively. In six of the solid ACCs, intratumour heterogeneity was delineated between the cribriform/tubular and solid components. NOTCH1 and FGFR2 mutations as well as NOTCH2 amplification were restricted to the solid component, indicating clonal selection within the same tumour. In two recurrent/metastatic solid ACCs, the subclones evolved in progression for local relapse and distant metastasis, although they manifested close genomic resemblance to primary tumours. Guided by the genetic profiles, the preclinical efficiency of the gamma-secretase inhibitor BMS-906024 was evaluated in patient derived xenograft models (PDXs) with activating NOTCH1 mutations and demonstrated robust antitumour effects. Our report revealed intratumour heterogeneity among solid-types within an ACC as well as the inter-tumour evolution of dominant clones among two primary and recurrent/metastatic tumours. In contrast to cribriform/tubular ACCs, solid-type ACCs should be approached with a distinct therapeutic strategy, particularly targeting NOTCH1. Microdissecting the highest grade component guided by histology is a highly recommended tumour sampling strategy and facilitates the detection of key molecular targets.

Pathological evaluation of tumor grade for salivary adenoid cystic carcinoma: A proposal of an objective grading system

Three pathological grading systems advocated by Perzin/Szanto, Spiro, and van Weert are currently used for adenoid cystic carcinoma (AdCC). In these systems, the amount or presence of the solid tumor component in AdCC specimens is an important index. However, the “solid tumor component” has not been well defined. Salivary AdCC cases (N = 195) were collected after a central pathology review. We introduced a novel criterion for solid tumor component, minAmax (minor axis maximum). The largest solid tumor nest in each AdCC case was histologically screened, the maximum oval fitting the solid nest was estimated, and the length of the minor axis of the oval (minAmax) was measured. The prognostic cutoff for the minAmax was determined using training and validation cohorts. All cases were evaluated for the four grading systems, and their prognostic impact and interobserver variability were examined. The cutoff value for the minAmax was set at 0.20 mm. Multivariate prognostic analyses showed the minAmax and van Weert systems to be independent prognostic tools for overall, disease‐free, and distant metastasis‐free survival while the Perzin/Szanto and Spiro systems were selected for overall survival but not for disease‐free or distant metastasis‐free survival. The highest hazard ratio for overall survival (11.9) was obtained with the minAmax system. The reproducibility of the minAmax system (kappa coefficient of 0.81) was scored as very good while those of the other three systems were scored as moderate. In conclusion, the minAmax is a simple, objective, and highly reproducible grading system useful for prognostic stratification for salivary AdCC.