Salivary gland lesions: recent advances and evolving concepts

Percutaneous injection of sclerosant agents as an effective treatment for cystic malformations of the head and neck

PURPOSE

To evaluate the clinical and aesthetic outcome of percutaneous injection of sclerosant agents to treat head and neck cystic malformations (HNCM) and to assess their recurrence rate based on histology and site.

METHODS

Fifty-four subjects (mean age 46 years) with HNCM treated by percutaneous injection of sclerosant agents between January and December 2017 were included. Imaging and clinical data before and after the procedure were collected. Quality of Life Index, Pain Visual Analogue Scale, and Aesthetic Scale scores were measured to assess clinical and aesthetic outcomes. A size reduction of ≥ 70% assessed through the visual scale was considered significant.

RESULTS

Of the 54 HNCM, there were 26 (48%) lymphatic malformations (LM), 13 (24%) salivary epithelial duct cysts of the parotid gland, 12 (22%) salivary mucoceles, and 3 (5%) branchial cysts. A significant size reduction and a satisfactory clinical-aesthetic outcome were observed in all types of LM. The number of reinterventions was significantly associated with the number of lesions (p < 0.001). The lowest number of interventions was observed in macrocystic lymphatic malformations (average of 1.2 interventions). All salivary epithelial duct cysts showed a significant reduction in size, a satisfactory clinical-aesthetic outcome, and an average of 1.16 interventions per patient. Mucoceles had a worse response, with only 3/14 patients showing a satisfactory and long-lasting clinical outcome (average of 1.16 interventions). Treatment of branchial cysts showed the worst outcome with a limited clinical response (3/3).

CONCLUSION

Percutaneous injection of sclerosant agents may be considered as a first-line treatment for LM and salivary epithelial duct cysts.

Secretory Carcinoma of Salivary Glands: A Case Series and Review of Literature

Mammary analogue of secretory carcinoma is a recently described entity in WHO 2017 classification of head and neck tumours. It resembles secretory carcinoma of breast. It usually affects the salivary glands and has an indolent behaviour. We reviewed five cases of Mammary analogue of secretory carcinoma in our institute and compared our results with existing literature. All the patients underwent surgical resections and appropriate adjuvant treatment. Immunohistochemistry is an alternative cost effective tool as compared to genetic testing to differentiate secretory carcinoma from its mimickers. Surgery with adequate margins followed by adjuvant therapy is the treatment of choice.

Amide proton transfer-weighted magnetic resonance imaging for the differentiation of parotid gland tumors

Purpose

To assess the usefulness of amide proton transfer-weighted (APTw) imaging in the differentiation of parotid gland tumors.

Materials and methods

Patients with parotid gland tumors who underwent APTw imaging were retrospectively enrolled and divided into groups according to pathology. Two radiologists evaluated the APTw image quality independently, and APTw images with quality score ≥3 were enrolled. The maximum and average values of APTw imaging for tumor lesions (APTmax and APTmean) were measured. The differences in APTmax and APTmean were compared between malignant tumors (MTs) and benign tumors (BTs), as well as between MTs and pleomorphic adenomas (PAs) and between MTs and Warthin tumors (WTs). Independent-samples t-test, Kruskal-Wallis H test, and receiver operating characteristic (ROC) curve analyses were used for statistical analysis.

Results

Seventy-three patients were included for image quality evaluation. In this study, 32/73 and 29/73 parotid tumors were scored as 4 and 3, respectively. After excluding lesions with quality score ≤2 (12/73), the APTmean and APTmax of MTs were 4.15% ± 1.33% and 7.43% ± 1.61%, higher than those of BTs 2.74% ± 1.04% and 5.25% ± 1.54%, respectively (p < 0.05). The areas under the ROC curve (AUCs) of the APTmean and APTmax for differentiation between MTs and BTs were 0.819 and 0.821, respectively. MTs indicated significantly higher APTmean and APTmax values than those of PAs (p < 0.05) and WTs (p < 0.05). The AUCs of the APTmean and APTmax for differentiation between MTs and PAs were 0.830 and 0.815 and between MTs and WTs were 0.847 and 0.920, respectively.

Conclusion

Most APTw images for parotid tumors had acceptable image quality for APTw value evaluation. Both APTmax and APTmean can be used to differentiate MTs from BTs and to differentiate MTs from subtype parotid gland tumors.

The potential of somatostatin receptor 2 as a novel therapeutic target in salivary gland malignant tumors

BACKGROUND

Treatment regimens for patients with metastatic or recurrent post-radiation, locoregional, unresectable salivary cancer are limited. An inverse correlation between somatostatin receptor 2 (SSTR2) and the proliferating marker Ki-67 in neuroendocrine tumors has enabled a treatment plan for metastatic disease, utilizing peptide receptor radionuclide therapy. Interestingly, healthy salivary glands express high levels of SSTR2. In this study, the presence of SSTR2, its correlation with Ki-67 in glandular salivary carcinomas and the clinical applicability thereof was determined.

METHODS

In the retrospective part of this study, 76 adequate tumor tissue specimens obtained from patients diagnosed with primary or metastatic salivary carcinomas between 1988 and 2016, were collected for tissue array and histologically classified. Immunohistochemistry was performed to determine the presence, relative expression and potential correlation of SSTR2 and Ki-67. The clinical significance of SSTR2 expression was determined by prospectively assessing ⁶⁸Ga-DOTATATE uptake using PET-CT imaging, in patients diagnosed with metastatic salivary gland malignant tumors between 2015 and 2016.

RESULTS

Sixty-three primary cancer tumors and 14 metastatic tumors were tested. All tumor subtypes were found to express SSTR2 to some extent. The highest expression was seen in Mucoepidermoid carcinoma (MEC) tissues where the majority of specimens (86.4%) expressed SSTR2. A relatively strong immunohistochemical staining score for SSTR2 was observed in MEC, adenoid cystic carcinoma and polymorphous adenocarcinoma. Interestingly, an inverse correlation between SSTR2 and Ki-67 expressions was observed (44%) in MEC tissue. Uptake of ⁶⁸Ga-DOTATATE was visualized using PET-CT imaging in 40% of patients, across metastatic MEC and ACC. All observations were found to be statistically significant.

CONCLUSION

This study confirms the expression of SSTR2 in glandular salivary carcinomas and an inverse correlation in expression levels between SSTR2 and Ki-67. This lays a foundation for novel treatment options in salivary metastatic cancers where SSTR2 may be a potential novel therapeutic target.

Functional Specialization of Human Salivary Glands and Origins of Proteins Intrinsic to Human Saliva

Salivary proteins are essential for maintaining health in the oral cavity and proximal digestive tract, and they serve as potential diagnostic markers for monitoring human health and disease. However, their precise organ origins remain unclear. Through transcriptomic analysis of major adult and fetal salivary glands and integration with the saliva proteome, the blood plasma proteome, and transcriptomes of 28+ organs, we link human saliva proteins to their source, identify salivary-gland-specific genes, and uncover fetal- and adult-specific gene repertoires. Our results also provide insights into the degree of gene retention during gland maturation and suggest that functional diversity among adult gland types is driven by specific dosage combinations of hundreds of transcriptional regulators rather than by a few gland-specific factors. Finally, we demonstrate the heterogeneity of the human acinar cell lineage. Our results pave the way for future investigations into glandular biology and pathology, as well as saliva's use as a diagnostic fluid.

Fluorescent In Situ Hybridization in Surgical Pathology Practice

There have been rapid and significant advances in diagnostic and predictive molecular techniques in recent years with profound impact on patient care. In situ hybridization (ISH) studies have become well entrenched in surgical pathology practice and their role in the evaluation of HER2 in breast carcinoma and their diagnostic utility in soft tissue pathology are well known. Fluorescent ISH is being increasingly used in other sites such as the head and neck and the gynecologic tract. Like most tests in surgical pathology, ISH studies require good quality tissue, correlation with clinical and histopathologic findings, and adherence to guidelines for optimal assay performance and interpretation. Although ISH studies are largely performed in tertiary centers, the tissue is often processed by a variety of laboratories and the referring pathologists are required to discuss the need, relevance, and significance of these tests and the results with their clinical colleagues. Here we review the predictive and diagnostic utility of fluorescent ISH studies in a variety of organ systems, the preanalytical factors that may affect the results, and the pitfalls in the interpretation that all practicing surgical pathologists should be aware of.

Expanding primary cells from mucoepidermoid and other salivary gland neoplasms for genetic and chemosensitivity testing

Restricted availability of cell and animal models is a rate-limiting step for investigation of salivary gland neoplasm pathophysiology and therapeutic response. Conditionally reprogrammed cell (CRC) technology enables establishment of primary epithelial cell cultures from patient material. This study tested a translational workflow for acquisition, expansion and testing of CRC-derived primary cultures of salivary gland neoplasms from patients presenting to an academic surgical practice. Results showed that cultured cells were sufficient for epithelial cell-specific transcriptome characterization to detect candidate therapeutic pathways and fusion genes, and for screening for cancer risk-associated single nucleotide polymorphisms (SNPs) and driver gene mutations through exome sequencing. Focused study of primary cultures of a low-grade mucoepidermoid carcinoma demonstrated amphiregulin-mechanistic target of rapamycin-protein kinase B (AKT; AKT1) pathway activation, identified through bioinformatics and subsequently confirmed as present in primary tissue and preserved through different secondary 2D and 3D culture media and xenografts. Candidate therapeutic testing showed that the allosteric AKT inhibitor MK2206 reproducibly inhibited cell survival across different culture formats. By contrast, the cells appeared resistant to the adenosine triphosphate competitive AKT inhibitor GSK690693. Procedures employed here illustrate an approach for reproducibly obtaining material for pathophysiological studies of salivary gland neoplasms, and other less common epithelial cancer types, that can be executed without compromising pathological examination of patient specimens. The approach permits combined genetic and cell-based physiological and therapeutic investigations in addition to more traditional pathologic studies, and can be used to build sustainable bio-banks for future inquiries.This article has an associated First Person interview with the first author of the paper.

Current State of Knowledge on Salivary Gland Cancers

Salivary gland cancers (SGCs), categorized as head and neck cancers (HNCs), constitute about 6% of head and neck cancer diagnoses based on estimate by American Head and Neck Society. Salivary gland tumors originate from different glandular cell types and are thus morphologically diverse. These tumors arise from any of the three major and various minor salivary glands. The incidence of SGCs has slowly increased during the last four decades. The etiology of SGCs is mostly unknown; however, specific gene mutations are associated with certain types of salivary tumors. Treatment options include surgical resection, radiation therapy (RT), chemotherapy, and multimodality therapy. HNC patients treated with RT often develop xerostomia and salivary hypofunction due to damaged salivary glands. In this review, we discuss etiology of SGCs, present findings on the role of autophagy in salivary tumorigenesis, review adverse effects of radiation treatment, and examine remedies for restoration of salivary function.

Diagnostic and therapeutic modalities for 287 malignant and benign salivary tumors: A cohort study

BACKGROUND

Salivary gland tumors (SGT's), 3-10% of head/neck tumors, exhibit a striking range of morphological diversity. This minimally symptomatic disease can be challenging to diagnose, and therapeutic policy is still controversial.

METHODS

We compared benign and malignant cohorts according to diagnostic modality utilized and therapeutic modality administered over 20 years in a single medical center.

RESULTS

Of 287 cases, 216 had benign tumors and 71 had malignant tumors. Treatment was surgery-based in 99% of cases, often accompanied by radiotherapy and/or chemotherapy. Rates of imaging and biopsy for diagnosis were significantly higher in malignant than benign tumors. Fine-needle aspiration (FNA) was used in 90.3% of benign tumors. Of 71 malignant tumors, 69 underwent surgery to fully remove the malignant tumor. Adjuvant therapy included 22 neck dissections (30%), 28 radiotherapy (39.4%), 12 chemotherapy (16.9%) and 10 combined radio-chemotherapy (14.1%). Partial parotidectomy, submandibular sialoadenectomy and local excision were used in 78.1%, 8.3% and 6.9% of benign cases. Total parotidectomy, sub-total maxillectomy and wide excision were used in 16.9%, 12.7% and 22.6% of malignant cases.

DISCUSSION

Diagnostic and therapeutic modalities for treatment of salivary tumor at our hospital are presented and discussed with respect to others. A paradigm of therapy administered in our institute is presented.

Cytokeratin immunoprofile of primary and metastatic adenoid cystic carcinoma of salivary glands: a report of two cases

Distant metastases from salivary gland tumors are considered infrequent: the incidence of distant metastases ranges from 24% to 61% according to different histotypes and to the site of the primary mass. The most common site of distant metastases due to salivary gland malignancies is the lung. From the pathology point of view, cytokeratins (CK) are important differentiation markers in salivary gland tumors, which are often used for the diagnostic process. Their employment also may be useful to identify and confirm the diagnosis of their distant metastases. We report the expression of CK in two cases of primary and metastatic adenoid cystic carcinoma (ACC) and their CK profiles of the primary and metastatic masses. Both patients—one male and one female—were diagnosed with an ACC cribriform and tubular, respectively, with lung metastases. In case 1, the metastatic mass presented the same histotype and CK profile of the primary tumor. For case 2, the metastatic lung mass was distinct from the primary mass (a solid ACC) and presented a different CK profile. Although salivary gland metastatic disease presents a poor prognosis, both patients reported herein are alive despite the presence of the disease in long-term follow-up. Therefore, the modifications seen in the CK profiles do not appear to be predictive of tumor behavior and outcome. The use of a CK profile seems to be useful to identify the nature of a distant mass and its possible correlations with a primary salivary gland tumor.

Altered expression of apoptosis-regulating miRNAs in salivary gland tumors suggests their involvement in salivary gland tumorigenesis

Salivary gland tumors comprise a heterogeneous group of lesions with different histological features and diverse clinical pathophysiology. They account for about 3% of all head and neck tumors. Apoptosis plays an important role during morphogenesis of glandular structures, including that of the salivary gland. Recent studies have demonstrated that several microRNAs (miRNAs) are involved in the control of apoptosis. The aim of the present study was to determine the expression of apoptosis-related miRNAs (miR-15a, miR-16, miR-17-5p, miR-20a, miR-21, miR-29, and miR-34) and their target mRNAs in 25 pleomorphic adenomas, 23 mucoepidermoid carcinomas, and 10 non-neoplastic salivary gland samples by real-time RT-PCR. We observed upregulation of miR-15a, miR-16, miR-17-5p, miR-21, miR-29, and miR-34a in pleomorphic adenomas. The expression of miR-21 and miR-34a was upregulated in 91 and 74% of mucoepidermoid carcinomas, respectively. Downregulation of miR-20a was observed in 75% of pleomorphic adenomas and in 57% of mucoepidermoid carcinomas. APAF1, BAX, BCL2, BID, CASP2, CASP8, DIABLO , and TP53 transcripts were upregulated in both tumor types. BAD transcripts were upregulated in pleomorphic adenomas. CASP3 and CASP6 transcripts were upregulated in mucoepidermoid carcinomas. BCL2, CASP2, CASP6, and CASP8 proteins were mostly absent in mucoepidermoid carcinomas but expressed in few cells in pleomorphic adenomas. Our study provides evidence of alterations in the expression of apoptosis-regulating miRNAs in salivary gland tumors, suggesting possible involvement of these microRNAs in salivary gland tumorigenesis.

Salivary gland hybrid tumour revisited: could they represent high-grade transformation in a low-grade neoplasm?

Salivary gland hybrid tumour, first described in 1996, is a very rare neoplasm for which exact morphological criteria have not been universally agreed upon. In contrast, the concept of high-grade transformation (HGT) in salivary neoplasms has been widely accepted during the last decade, and the number of reported cases is rapidly increasing. A review of the literature revealed 38 cases of hybrid tumour reported in 22 publications. During approximately the same time period, well over 100 cases of HGT in salivary neoplasms have been reported. There are important histological similarities between hybrid tumours and salivary tumours with HGT. In the latter, containing one tumour component of low-grade malignancy and the other of high grade, the two tumour components are not entirely separated and appear to originate in the same area. Virtually, all cases reported as hybrid tumour had no clear lines of demarcation between the two tumour types. We are inclined to suggest that most of the 38 cases of hybrid tumours described in the literature would today better be called tumour with HGT rather than hybrid tumour. The relative proportion of the two components may vary, and the high-grade component is sometimes very small, which emphasises the importance of very generous sampling of the surgical specimen. The molecular genetic mechanisms responsible for HGT, including what used to be called hybrid tumour, remain largely unknown. Abnormalities of a few genes (including p53, C-MYC, cyclin D1, HER-2/neu) have been documented. As insufficient data exist on gene abnormalities in these lesions, conclusions as to whether or not they have a common origin and which mechanisms are involved in transformation cannot be drawn. Due to the small number of cases reported, many of which lack follow-up details; indicators of prognosis of hybrid tumours are not available, but their behaviour seems to be similar to that of tumours with HGT, i.e. an accelerated aggressive course. HGT of salivary gland neoplasms greatly influences macroscopic and microscopic evaluation of the specimen but also, given the high incidence of metastases and morbidity, carries significant treatment implications.

Primary Pulmonary Salivary Gland-type Tumors: A Review and Update

Pulmonary salivary gland-type tumors (SGT) comprise a very small proportion of primary lung neoplasms. The most common tumors among this group are mucoepidermoid carcinoma and adenoid cystic carcinoma. Contrary to the head and neck region, benign SGT such as pleomorphic adenomas are exceedingly rare in the pulmonary system. More recently, 2 additional SGT, namely hyalinizing clear cell carcinoma and salivary duct-like carcinoma were recognized as primary lung tumors expanding the spectrum of SGT that have been described to originate in the tracheobronchial system. Primary pulmonary SGT must be clinically excluded from metastatic salivary gland neoplasms as their morphology is indistinguishable from that of their salivary gland counterparts. Little is known about the clinical behavior and best treatment approach for these unusual tumors. In this review, we provide a comprehensive summary of primary pulmonary SGT with particular emphasis on morphologic characteristics and latest developments in terms of immunohistochemical and molecular techniques.