High-grade salivary carcinomas: A current insight on diagnostic pathology and the key to clinical decision making

High-grade carcinomas of the salivary glands are a group of several tumor entities with highly malignant histologic appearances, and have an aggressive biological behavior accompanied by poor a prognosis. In general, they require more intensive treatment than low- or intermediate-grade carcinomas. High-grade salivary carcinomas are rare and the microscopic features often overlap between different tumor types, making an appropriate diagnosis challenging in daily practice settings. However, with recent rapid advances in molecular pathology and molecular-targeted therapy in this field, there is a growing need to properly classify tumors, rather than just diagnosing the cases as "high-grade carcinomas". This leads to specific treatment strategies. In this article, we review representative high-grade salivary gland carcinomas, including salivary duct carcinoma and its histologic subtypes, high-grade mucoepidermoid carcinoma, solid-type adenoid cystic carcinoma, and high-grade transformation of low- or intermediate-grade carcinomas, and discuss their differential diagnoses and clinical implications. Other rare entities, such as neuroendocrine carcinoma, NUT carcinoma, and metastatic carcinoma, should also be considered before diagnosing high-grade carcinoma, NOS. Of these tumors, salivary duct carcinoma has received the most attention because of its strong association with androgen deprivation and anti-HER2 therapies. Other tumor-type-specific treatments include anti-TRK therapy for high-grade transformation of secretory carcinoma, but further therapeutic options are expected to be developed in the future. It should be emphasized that detailed histological evaluation with adequate sampling, in addition to the effective use of molecular ancillary tests, is of the utmost importance for a suitable diagnosis.

The extent of androgen receptor and HER2 expression allows for targeted therapy in most cases of salivary duct carcinoma: analysis of clinical and histopathological data in a tertiary care center

PURPOSE

The incidence of salivary duct carcinoma (SDC) seems to be underestimated due to inaccurate classification. Further, the frequency of SDC patients with targeted therapy options according to current guidelines is unclear. Therefore, this study aimed at (a) describing the proportion of SDC among salivary gland carcinoma (SGC) before and after reclassification of cases initially classified as adenocarcinoma, not otherwise specified (ANOS); and (b) quantifying the frequency of SDC patients with targeted therapy options.

METHODS

All patients with SDC or ANOS treated in a tertiary care center between 1996 and 2023 were identified. Histopathological diagnosis was verified for patients primarily diagnosed with SDC and reviewed for patients initially diagnosed with ANOS. Clinical data for SDC patients were retrieved from clinical charts. Immunohistochemical (IHC) androgen receptor (AR) and HER2 staining was performed.

RESULTS

Among 46 SDC, 34 were primarily diagnosed as SDC and 12 had initially been classified as ANOS. The proportion of SDC among SGC was 12.1% and was rising when comparing the time periods 2000-2015 (7.1-11.5%) versus 2016-2023 (15.4-18.1%). Nuclear AR staining in > 70% of tumor cells was found in 56.8% and HER2 positivity (IHC 3 +) in 36.4% of cases. 70.5% of patients showed AR staining in > 70% of tumor cells and/or HER2 positivity and therefore at least one molecular target. 5-year overall and disease-free survival (DFS) were 62.8% and 41.0%. Multivariate Cox regression revealed positive resection margins (HR = 4.0, p = 0.03) as independent negative predictor for DFS.

CONCLUSIONS

The results suggest a rising SDC incidence and show that the extent of the AR and HER2 expression allows for targeted therapy in most SDC cases.

Near-infrared photoimmunotherapy for salivary duct carcinoma

In Japan, near-infrared photoimmunotherapy (NIR-PIT) was introduced in 2021 as a treatment option for unresectable recurrent head and neck cancer. The treatment targets the epidermal growth factor receptor (EGFR), which is overexpressed in 80-90 % of head and neck squamous cell carcinoma (HNSCC). NIR-PIT should theoretically show therapeutic efficacy if EGFR is expressed, even in nonsquamous cell carcinomas (non-SCC). To the best of our knowledge, there are no case reports of NIR-PIT for non-SCC. We performed NIR-PIT in a patient with non-SCC of the head and neck region. After performing two NIR-PIT treatments, small free clusters of residual tumor cells were observed. Immunostaining in this specimen revealed EGFR expression in residual tumor cells. The residual tumor cells had been irradiated sufficiently to achieve necrosis. It is suggested that not only laser irradiation and expression of EGFR but also other factors are involved in the efficacy of this treatment. Further investigation for these other factors is warranted.

Efficacy of Cetuximab Combined with Paclitaxel in Patients with Recurrent Salivary Gland Carcinoma: A Retrospective Observational Study

INTRODUCTION

Due to the rarity and various histological types, a standard chemotherapy regimen for recurrent or metastatic salivary gland carcinoma (SGC) has not been established. Molecular-targeted therapy is a novel cancer therapy based on the expression of target molecules. However, few molecular-targeted therapy types have shown satisfactory efficacy for patients with SGC. Our study described promising results of epidermal growth factor receptor (EGFR)-targeting therapy with paclitaxel in patients with SGC.

METHODS

The medical records of patients with recurrent SGC treated with weekly cetuximab combined with paclitaxel (Cmab-PTX) between December 2017 and December 2022 at our institutions were retrospectively analyzed.

RESULTS

Seven patients with SGC received Cmab-PTX therapy. The median age was 76 years. All patients were high-grade histological types, and EGFR expression was positive in all examined patients. Cmab-PTX was administered for a median period of 20 months (range of 2-36 months). The overall responses were three with complete response, two with partial response, one with stable disease (>24 weeks), and one with progressive disease. The objective response and disease control rates were 71.4% and 85.7%, respectively. Progression-free survival ranged between 2 and 36 months (median 12 months), whereas overall survival ranged between 4 and 111 months (median 36 months). One patient experienced a grade 4 adverse event (neutropenia), which was conservatively manageable.

CONCLUSION

Although the treatment sensitivity of SGC with high-grade histological types is usually poor, Cmab-PTX could be a promising treatment regimen for recurrent SGC. Due to the rarity and various histological types, a standard chemotherapy regimen for recurrent or metastatic salivary gland carcinoma (SGC) has not been established. Molecular-targeted therapy is a novel cancer therapy based on the expression of target molecules. However, few molecular-targeted therapy types have shown satisfactory efficacy in patients with SGC. Our study described promising results of cetuximab (Cmab), epidermal growth factor receptor (EGFR)-targeting therapy with paclitaxel (PTX) in patients with SGC. Seven patients with SGC received Cmab-PTX therapy. The median age was 76 years. All patients were high-grade histological types, and EGFR expression was positive in all examined patients. Cmab-PTX was administered for a median period of 20 months. The overall responses were three with complete response, two with partial response, one with stable disease (>24 weeks), and one with progressive disease. The objective response rate was 71.4%. Progression-free survival ranged between 2 and 36 months (median 12 months), whereas overall survival ranged between 4 and 111 months (median 36 months). One patient experienced a grade 4 adverse event (neutropenia), which was conservatively manageable. Our study revealed a preferable objective response rate of Cmab-PTX for patients with high-grade SGC. Although the treatment sensitivity of SGC with high-grade histological types is usually poor, Cmab-PTX could be a promising treatment regimen for recurrent SGC.

Salivary Duct Carcinoma Arising in a Warthin Tumor of the Parotid Gland: A Rare Case Report with Review of Literature and PD-L1 Expression

Warthin's tumor is the second most common neoplasm of the parotid gland and consists of 2 components, including lymphoid stroma and glandular epithelium. Malignant transformation in this tumor is mostly seen in the lymphoid component; however, the carcinomatous transformation of the epithelial component is extremely rare. Cases of latter reported in the literature include squamous cell carcinoma, adenocarcinoma, mucoepidermoid carcinoma, oncocytic carcinoma, Merkel cell carcinoma, and undifferentiated carcinoma. We describe an extremely rare case of salivary duct carcinoma arising in a Warthin tumor in a 64-year-old male. Patient presented with an enlarging left parotid mass, biopsy of which showed salivary duct carcinoma. He subsequently underwent left parotidectomy along with left level II-IV lymph node dissection. Histology revealed both in situ as well as invasive salivary duct carcinoma arising from Warthin tumor. Immunohistochemistry showed tumor cells positive for CK7, AR, and GATA3, while p63 highlighted the myoepithelial cell layer in the in situ component. Her2 was 2+ by immunohistochemistry. In addition, PD-L1 IHC revealed positive expression with a combined positive score of 20%.

Nectin-4 is frequently expressed in primary salivary gland cancer and corresponding lymph node metastases and represents an important treatment-related biomarker

Many locally advanced and metastatic salivary gland carcinomas (SGC) lack therapeutic targets. Enfortumab vedotin, an antibody-drug conjugate binding to Nectin-4, recently gained FDA approval for third-line urothelial carcinoma. Therefore, the aim of this study was to assess the expression of Nectin-4 in primary SGC and corresponding lymph node metastases and to correlate it with clinicopathological data. Immunohistochemical staining for Nectin-4 was performed for patients who had undergone surgery with curative intent for primary SGC of the parotid or submandibular gland in a tertiary referral center between 1990 and 2019. One hundred twenty-two primary SGC and twenty corresponding lymph node metastases were included. Nectin-4 was expressed in 80.3% of primary SGC with a mean Histo(H-)score of 61.2 and in 90.0% of lymph node metastases with a mean H-score of 75.6. A moderate or high Nectin-4 expression was found in 25.9% of salivary duct carcinomas (SaDu) and in 30.7% of adenoid cystic carcinomas (ACC). SaDu patients with a lower T-stage (p = 0.04), no loco-regional lymph node metastases (p = 0.049), no vascular invasion (p = 0.04), and no perineural spread (p = 0.03) showed a significantly higher mean Nectin-4 H-score. There was a statistical tendency towards a more favorable disease-free survival among SaDu patients with a higher Nectin-4 expression (p = 0.09). Nectin-4 is expressed in SGC and therefore represents a potential therapeutic target, especially in entities with a high rate of local recurrence and metastatic spread such as SaDu and ACC.

Loss of BAP1 Protein Expression by Immunohistochemistry in the Salivary Duct Carcinoma Component of an Intracapsular Carcinoma ex Pleomorphic Adenoma of the Parotid Gland

BACKGROUND

BRCA1-associated protein 1 (BAP1) is a tumor suppressor gene that is altered in a variety of neoplasms as well as in BAP1 tumor predisposition syndrome. BAP1 alterations are associated with aggressive behavior in some malignancies and may have treatment implications in future. We present the first documented case of loss of BAP1 protein expression by immunohistochemistry in the salivary duct carcinoma (SDC) component of an intracapsular carcinoma ex pleomorphic adenoma (CXPA) in the context of molecular loss of function of BAP1 in the neoplasm.

METHODS

A woman of approximately 55 years of age presented with a deep parotid lobe mass, which was resected and found to be CXPA. BAP1 immunohistochemistry and next-generation sequencing was performed to further characterize the neoplasm.

RESULTS

The neoplasm showed loss of BAP1 protein expression in the SDC component but retention in the residual pleomorphic adenoma (PA). Next-generation sequencing confirmed a BAP1 loss of function alteration in the neoplasm.

CONCLUSION

This is the first documented case report of BAP1 protein expression loss in the SDC component of a CXPA. Future studies are needed to investigate the relevance of BAP1 alterations in SDC and CXPA, which may have prognostic and treatment implications.

Prognostic value and clinicopathological roles of the tumor immune microenvironment in salivary duct carcinoma

Salivary duct carcinoma (SDC) is an aggressive type of salivary gland carcinoma. Recently, immunotherapies targeting immune checkpoints, including PD1, PD-L1, CTLA4, and LAG3, have had a considerable prognostic impact on various malignant tumors. The implementation of such immune checkpoint inhibitor (ICI) therapies has also been attempted in cases of salivary gland carcinoma. The tumor immune microenvironment (TIME) is implicated in tumorigenesis and tumor progression and is closely associated with the response to ICI therapies. However, the TIME in SDC has not been fully explored. We examined the immunohistochemical expression of CD8, FOXP3, PD1, PD-L1, CTLA4, LAG3, and mismatch repair (MMR) proteins, tumor-infiltrating lymphocytes (TILs), and microsatellite instability (MSI) status in 175 cases of SDC. The associations between these TIME-related markers and the clinicopathological factors and prognosis were evaluated. An elevated expression of CD8, FOXP3, PD1, CTLA4, and LAG3 was associated with more aggressive histological features and an advanced N and/or M classification, elevated Ki-67 index, and poor prognosis. Furthermore, cases with a high PD-L1 expression exhibited more aggressive histological features and adverse clinical outcomes than those with a low expression. Alternatively, there was no significant correlation between TILs and clinicopathological factors. No SDC cases with an MSI-high status or MMR deficiency were found. The coexistence of both an immunostimulatory and immunosuppressive TIME in aggressive SDC might play a role in the presence of T-cell exhaustion. The contribution of multiple immune escape pathways, including regulatory T cells and immune checkpoints, may provide a rationale for ICI therapy, including combined PD1/CTLA4 blockade therapy.

High-grade non-intestinal type sinonasal adenocarcinoma with ETV6::NTRK3 fusion, distinct from secretory carcinoma by immunoprofile and morphology

We report 2 cases of high-grade sinonasal adenocarcinoma with a distinct morphological and immunohistochemical phenotype. Albeit histologically different from secretory carcinoma of the salivary glands, both tumors presented here share an ETV6::NTRK3 fusion. The highly cellular tumors were composed of solid and dense cribriform nests, often with comedo-like necroses in the center, and minor areas with papillary, microcystic, and trabecular formations without secretions, mostly located at the periphery of the lesion. The cells displayed high-grade features, with enlarged, crowded, and often vesicular nuclei with conspicuous nucleoli and brisk mitotic activity. The tumor cells were immunonegative for mammaglobin while showing immunopositivity for p40/p63, S100, SOX10, and GATA3, as well as for cytokeratins 7, 18, and 19. For the first time, we describe 2 cases of primary high-grade non-intestinal type adenocarcinomas of the nasal cavity, distinct from secretory carcinoma by morphology and immunoprofile, harboring the ETV6::NTRK3 fusion.

Frequent apocrine changes in pleomorphic adenoma with malignant transformation: a possible pre-malignant step in ductal carcinoma ex pleomorphic adenoma

BACKGROUND

The most common type of carcinoma ex pleomorphic adenoma (CPA) is histologically equivalent to salivary duct carcinoma, which has an apocrine phenotype. Invasive CPA is often accompanied by non-invasive or in situ carcinoma, an observation that suggests the presence of precursor lesions. The aim of this study was to identify candidate precursor lesions of CPA within pleomorphic adenoma (PA).

METHODS

Eleven resected cases of CPA with residual PA and 17 cases of PA with atypical changes were subjected to immunohistochemistry (IHC) for p53, human epidermal growth factor receptor 2 (HER2), androgen receptor (AR), pleomorphic adenoma gene 1, gross cystic disease fluid protein-15 (GCDFP-15), and anti-mitochondrial antibody.

RESULTS

Invasive or in situ carcinoma cells in all CPAs were positive for AR, GCDFP-15, and HER2. Atypical foci in PAs corresponded to either apocrine or oncocytic changes on the basis of their reactivity to AR, GCDFP-15, and anti-mitochondrial antibody. Atypical cells in PAs surrounding CPAs had an apocrine phenotype without HER2 expression.

CONCLUSIONS

Our study identified frequent apocrine changes in residual PAs in CPA cases, suggesting a possible precursor role of apocrine changes. We recommend the use of HER2 IHC in atypical PAs, and that clinicians take HER2 positivity into serious consideration.

Prognostic models for estimating survival of salivary duct carcinoma: a population-based study

PURPOSE

In a large salivary duct carcinoma (SDC) cohort, we aimed to investigate the clinical factors influencing their survival outcomes and to further establish prognostic models.

METHODS

Data of patients with SDC were extracted from the Surveillance, Epidemiology, and End Results database (1975-2019). A retrospective analysis was conducted to explore the prognostic factors on overall survival (OS) and disease-specific survival (DSS), and corresponding nomograms were established.

RESULTS

A steady upward trend in the incidence of SDC was observed over the past four decades. Totally, 399 patients (280 in the training set and 199 in the testing set) were enrolled. Advanced T stage, lymph node metastasis, distant metastasis, and surgery were associated with favorable OS and DSS. Besides, age > 80 years exhibited worse OS. The selected variables above were used to construct nomograms and online web calculators that could accurately predict patient survival. In addition, risk stratification systems were generated to identify low- and high-risk patients. As the risk level increased, the risk of both patient mortality and disease-specific mortality increased.

CONCLUSIONS

The SDC incidence was low, but steadily increasing. The proposed prognostic models provided a robust and efficient approach to predict survival and risk stratification in SDC patients.

Clinical value of adjuvant therapy on the prognosis of ductal carcinoma of the major salivary gland: a large-scale cohort study

PURPOSE

To explore the clinical characteristics, prognostic factors, and value of adjuvant therapy for major salivary duct carcinoma (SDC).

METHODS

Data of SDC patients who received surgery was obtained from Surveillance, Epidemiology, and End Results (SEER) database (2004-2016). Kaplan-Meier and Cox regression analyses were performed to assess prognostic factors. Propensity score matching (PSM) was done to evaluate the clinical value of adjuvant therapy.

RESULTS

A total of 287 patients were enrolled. The 5-year overall survival (OS) and disease-specific survival (DSS) rates were 53.8% and 70.8%, respectively. In the univariate analysis, tumor size, T, N, TNM staging, SEER combined staging, number of regional lymph nodes examined, and number of positive lymph nodes were associated with OS and DSS. Age and primary surgical methods were also related to OS. Among patients with negative lymph nodes, patients with tumor size > 4 cm had significantly worse prognosis (P = 0.009). Multivariate analysis showed that age > 75 years, T3-4, and positive lymph nodes were independent risk factors for SDC. After PSM, the prognostic factors were age, tumor site, and T and N stage. Postoperative radiotherapy could improve OS in patients with tumor size > 4 cm (P = 0.049).

CONCLUSIONS

Advanced age, submandibular gland lesions, T3-4 stage, and lymph node involvement were independent prognostic factors for SDC. In patients with tumors > 4 cm, adjuvant radiotherapy improved the OS of SDC patients.

Androgen Deprivation Therapy for Intracranial Metastasis of a Salivary Duct Carcinoma: Case Report

Salivary duct carcinoma (SDC) is a rare subtype of salivary cancers associated with androgen receptor and human epidermal growth factor receptor 2 (HER2/neu) overexpression. It shows a high propensity to give rise to distant metastases mainly to the lung, the bone, and the liver. Intracranial metastases are rare. We report the case of a 61-year-old male patient with SDC developing intracranial metastases. Unresponsive to radiotherapy and anti-HER/neu targeted therapy the intracranial metastases showed a very good partial remission to androgen deprivation therapy with goserelin acetate. This case demonstrates the potential of a highly targeted therapy with a relatively cheap and well-known drug in a patient with a rare disease without other good therapeutic options, which is a good example of modern, personalized medicine.

Metastatic Salivary Duct Carcinoma with ERBB2 Amplification and Sequential Response to Ado-Trastuzumab Emtansine and Neratinib: A Case Report

Introduction

Salivary duct carcinoma (SDC) is an aggressive and rare subtype of salivary gland carcinoma. Surgical excision and radiotherapy are standard of care for early cancer. Chemotherapies with taxanes and platinum show overall response rates between 39% and 50%. SDCs are often associated with an overexpression of the androgen receptor (AR) and HER2/neu which have recently become druggable targets.

Case Presentation

Here, we report on an 84-year-old male patient with metastatic SDC of the right parotid gland. In 2017, he underwent a right total parotidectomy, a right neck dissection, and an infratemporal fossa clearance followed by 6 weeks of radiotherapy. In 2018, due to metastatic spread in the lungs, bones, and pararenal gland, a pathological workup of the tumor tissue was performed and revealed both AR and HER2 overexpression, respectively. Consequently, he underwent androgen deprivation therapy and, due to asymptomatic progression, sequentially human epidermal growth factor receptor 2 (HER-2)-targeted therapy with ado-trastuzumab emtansine and neratinib, which led to stable disease during the course of about 18 months. The electronically captured patient-reported outcome had demonstrated a good tolerance of all three therapeutic lines.

Conclusion

In conclusion, since effective standard therapeutic treatment options for SDC may often not be tolerable in older patients, the implementation of personalized and adaptive treatments, especially in patients with rare tumor types, might offer valuable treatment options.

A Pitfall of the Androgen Deprivation Therapy for Salivary Duct Carcinoma: Hormonal Therapy-Induced Castrate-Resistant Prostate Cancer

Introduction

Salivary duct carcinoma (SDC) is a rare, high-grade salivary gland malignancy. Recently, targeting the androgen receptor (AR) is one of the most promising new therapeutic strategies for AR-positive SDC.

Case Review

In this report, a 70-year-old man who was diagnosed with an AR-positive SDC underwent androgen deprivation therapy (ADT) as a treatment for recurrence after primary therapy. The ADT well contributed to control of SDC; however, the patient was referred to urologists for urinary hesitancy and slow flow and he was diagnosed as having castration-resistant prostate cancer.

Literature Review

Since SDC is a rare disease, it has been difficult to establish the most effective therapy. Nevertheless, several papers have reported the clinical benefit of ADT for AR-positive SDC, and the latest version of the National Comprehensive Cancer Network guidelines also states the importance of assessing for the presence of AR in SDC.On the other hand, in the field of urology, it is also known that although ADT is initially effective in prostate cancer patients, prostate cancer often develops into castrate-resistant prostate cancer due to the adaptation of prostate cancer cells to ADT for survival and growth.

Conclusion

We reported a case of castrate-resistant prostate cancer diagnosed during the ADT for metastatic SDC. The present case emphasizes the importance of screening for prostate cancer at the initiation of ADT treatment and during treatment.

Targeted molecular profiling of salivary duct carcinoma with rhabdoid features highlights parallels to other apocrine and discohesive neoplasms: which phenotype should drive classification?

BACKGROUND

Salivary duct carcinoma with rhabdoid features (SDC-RF) is a recently-described salivary gland tumor that bears striking histologic similarity to lobular carcinoma of the breast. While this tumor has an apocrine phenotype that supports classification as a variant of SDC, it infrequently arises in association with conventional SDC. Furthermore, discohesive architecture can be seen in non-apocrine salivary carcinomas, raising the possibility that discohesive growth should define a separate entity. In this study, we aimed to perform comprehensive molecular profiling of SDC-RF to better understand its pathogenesis and classification.

METHODS

We documented the clinicopathologic features of 9 cases of SDC-RF and performed immunostains including AR, GCDFP, and e-cadherin on all cases. We also performed targeted next generation sequencing (NGS) panels on 7 cases that had sufficient tissue available.

RESULTS

The SDC-RF represented 8 men and 1 woman with a median age of 67 years (range 63-83 years) and included 6 parotid, 2 buccal, and 1 submandibular primary. All tumors were uniformly composed of discohesive cells with abundant eosinophilic cytoplasm; signet-ring cell features were seen in 2 cases. All tumors were also positive for AR (100%) and GCDFP (100%), and 7 tumors (78%) displayed lost or abnormal e-cadherin. NGS highlighted concomitant PIK3CA and HRAS mutations in 4 tumors, with additional cases harboring TP53, PTEN, and AKT1 mutations. Furthermore, CDH1 alterations were seen in 6 cases, including a novel CDH1::CORO7 fusion. Among 5 patients with follow-up available, 3 (60%) developed local recurrence and widespread distant metastasis and died of disease at a median 20 months (range 10-48 months).

CONCLUSIONS

Overall, our findings confirm frequent CDH1 mutations and e-cadherin inactivation in SDC-RF, similar to discohesive tumors from other sites. We also highlight an apocrine molecular profile similar to conventional SDC. However, occasional AKT1 mutation and signet-ring features suggest SDC-RF may also be related to mucinous adenocarcinoma. As more salivary tumors with discohesive growth are identified, it may become clearer whether SDC-RF should remain in the SDC family or be recognized as a separate entity.

Paraneoplastic cerebellar degeneration with anti-Yo antibodies and an associated submandibular gland tumor: a case report

Background

As a debilitating syndrome, paraneoplastic cerebellar degeneration (PCD) remains challenging to treat. Further, anti-Yo antibody (directed against human cerebellar degeneration-related protein 2) detection in patients with PCD is associated with unsatisfactory responses to existing therapies. Here, we present the case of a 60-year-old woman who developed PCD with anti-Yo antibodies and a submandibular gland tumor.

Case presentation

A 60-year-old woman presented with a 5-day history of unsteadiness of gait and inadequate coordination of her extremities, along with truncal instability. Although walking without aid was possible, dysmetria of all four limbs, trunk, and gait ataxia was observed. While routine biochemical and hematological examinations were normal, the patient’s blood was positive for anti-Yo antibodies. When the neurological symptoms deteriorated despite administration of intravenous methylprednisolone, fluorodeoxyglucose-positron emission tomography (FDG-PET) and computed tomography (CT) images with contrast enhancement were performed, which showed a tumor in the left submaxillary gland. She underwent total left submandibular gland resection, including the tumor; histological and immunohistochemical results revealed a salivary duct carcinoma. She was administered intravenous methylprednisolone, followed by 10 plasma exchange sessions, intravenous immunoglobulins, and cyclophosphamide therapy. Following treatment, her symptoms were not alleviated, even after the reduction of anti-Yo titers.

Conclusions

Although tumor detection was delayed, early tumor detection, diagnosis, and PCD treatment are essential because any delay can result in the progression of the disorder and irreversible neurological damage. Therefore, we recommend that the possibility of a salivary gland tumor should be considered, and whole-body dual-modality CT, including the head and neck, and FDG-PET should be performed at the earliest for patients with well-characterized paraneoplastic antibodies when conventional imaging fails to identify a tumor.

Expression of Mucins in Different Entities of Salivary Gland Cancer: Highest Expression of Mucin-1 in Salivary Duct Carcinoma : Mucin-1 - highest expression in Salivary Duct Carcinoma

Therapeutic options for advanced salivary gland cancer (SGC) are rare. Therefore, it was the aim of this study to investigate the extent and intensity of Mucin-1 (MUC1), Mucin-16 (MUC16), and Mucin-5AC (MUC5AC) as potential molecular targets using immunohistochemistry. The medical records of all patients who underwent primary surgery for salivary gland cancer with curative intent in a tertiary referral center between 1990 and 2018 were reviewed. Immunohistochemical staining for MUC1, MUC16, and MUC5AC was performed for all patients with sufficient formalin-fixed paraffin-embedded material, and a semi-quantitative combined score derived from the H-score for the cytoplasmatic, the membranous and the apical membrane was built for the most common entities of SGC. 107 patients with malignancies of the parotid (89.7%) and the submandibular gland (10.3%) were included. The most common entities were mucoepidermoid carcinoma (MuEp; n = 23), adenoid cystic carcinoma (AdCy; n = 22), and salivary duct carcinoma (SaDu; n = 21). The highest mean MUC1 combined score was found in SaDu with 223.6 (±91.7). The highest mean MUC16 combined score was found in MuEp with 177.0 (±110.0). The mean MUC5AC score was low across all entities. A higher MUC1 combined score was significantly associated with male gender (p = 0.03), lymph node metastasis (p < 0.01), lymphovascular invasion (p = 0.045), and extracapsular extension (p = 0.03). SaDu patients with MUC16 expression showed a significantly worse 5-year progression-free survival than those without MUC16 expression (p = 0.02). This is the first study to give a comprehensive overview of the expression of MUC1, MUC16, and MUC5AC in SGC. Since advanced SGCs lack therapeutic options in many cases, these results warrant in vitro research on therapeutic targets against MUC1 in SaDu cell lines and xenograft models.

Case series of docetaxel, trastuzumab, and pertuzumab (DTP) as first line anti-HER2 therapy and ado-trastuzumab emtansine (T-DM1) as second line for recurrent or metastatic HER2-positive salivary duct carcinoma

OBJECTIVE

Salivary duct carcinoma (SDC) overexpresses Human Epidermal growth factor Receptor 2 (HER2) in 29-46% of cases, favoring anti-HER2 therapy. Here, we present the results of patients with recurrent or metastatic HER2-positive SDC treated with docetaxel, trastuzumab, and pertuzumab (DTP) as first line anti-HER2 therapy and subsequently ado-trastuzumab emtansine (T-DM1) in second line. Furthermore, we searched for potential biomarkers.

METHODS

Retrospective case series from a tertiary hospital. First line anti-HER2 treatment consisted of DTP, after progression T-DM1 was considered for patients with an adequate performance status. Objective response rate (ORR), progression-free survival (PFS) and overall survival (OS) were assessed and related to mRNA-based PI3K and MAPK signaling pathway activity scores.

RESULTS

Thirteen SDC HER2 + patients received DTP. In twelve evaluable patients, one complete response (CR) and six partial responses (PR) were observed (ORR 58%), with a median PFS of 6.9 months (95%-CI 5.3-8.5). Seven patients received subsequent T-DM1 in second line, resulting in four PR (ORR 57%), with a median PFS of 4.4 months (95%-CI 0-18.8). Median OS after start of DTP was 42.0 months (95%-CI 13.8-70.1). Grade ≥ 3 toxicity on DTP was seen in 39% of patients, and 14% on T-DM1. Highest combined PI3K and MAPK signaling was seen in the patient with CR and lowest in the patient with progressive disease on DTP.

CONCLUSION

In R/M HER2-positive SDC patients DTP followed by T-DM1 upon progression are promising treatments, leading to responses in the majority (58%) of the patients at an acceptable toxicity profile.

Genomic alteration in rare subtype of sarcomatoid salivary duct carcinoma

AIMS

Salivary duct carcinoma (SDC) is an aggressive salivary gland neoplasm with a poor prognosis. Morphologically, it has many variants including sarcomatoid SDC. We evaluated the morphological features, immunohistochemistry profile, and genomic alteration of the rare variant, sarcomatoid SDC.

METHODS AND RESULTS

We evaluated the clinicopathological and molecular pathology for rare variant of sarcomatoid SDC. Among 102 SDC patients, three had sarcomatoid SDC. Review of clinicopathological features and immunohistochemistry and targeted exome sequencing was performed according to carcinomatous and sarcomatoid areas, respectively. The tumors were present in two submandibular glands and one parotid gland. In one case, a SDC arose in carcinoma ex pleomorphic adenoma. All consisted of a conventional invasive ductal carcinoma area and sarcomatoid features including spindle cells and multinucleated giant cells. AR and epithelial membrane antigen (EMA) were positive in both carcinoma and sarcomatoid areas. Cytokeratin AE1/AE3 were negative in all sarcomatoid areas. Targeted exome sequencing revealed multiple heterogeneous alterations including PIK3CA and TP53. Genomic alterations were nearly identical between typical carcinoma and sarcomatoid areas.

CONCLUSIONS

Clinicopathological features of sarcomatoid SDCs were not different from typical SDC, and genomic alteration according to subtypes was also similar to that of the conventional type. Androgen receptor (AR) expression is helpful in the diagnosis of SDC. The findings indicate that EMA and AR are useful in diagnosing sarcomatoid SDC when the tumor is composed of predominantly sarcomatoid components.

Salivary Gland Cancers

Salivary gland carcinomas are a rare and heterogenous group of cancers with varying underlying biology and clinical behavior. A quickly evolving body of data has advanced the understanding of these tumors, leading to effective therapeutics for several histologic subtypes. Biologically rational clinical trials have developed from an understanding of MYB and NOTCH signaling in adenoid cystic carcinoma. The recognition of androgen receptor signaling and HER2-targeted therapy has offered therapeutic options in non-ACC salivary cancers. The use of TRK inhibitors in salivary secretory carcinoma has led to exceptional responses. Immunotherapy is an exciting new therapeutic avenue that requires further exploration.

Immunohistochemical Reactivity of Prostate-Specific Membrane Antigen in Salivary Gland Tumors

Prostate-specific membrane antigen (PSMA) is a transmembrane glycoprotein that is overexpressed in the prostate gland and prostate cancer. PSMA has been recently used in positron emission tomography/computed tomography (PET/CT) imaging and targeted alpha-radiation therapy (TAT) for prostate cancer. Recently, the tubarial gland, a type of minor salivary gland that is described as a new organ situated in the pharynx, is reported to express PMSA. Here, we studied the expression of PSMA in common benign and malignant salivary gland tumors. We performed immunohistochemistry for PSMA in 55 salivary gland tumors comprising 10 pleomorphic adenomas, 10 Warthin tumors, 9 basal cell adenomas, 9 adenoid cystic carcinomas, 9 mucoepidermoid carcinomas, and 8 salivary duct carcinomas. PSMA was expressed in 97% of benign tumors and 77% of malignant tumors. Moreover, PSMA was expressed in 59% of normal salivary glands adjacent to the tumor. PSMA is relatively expressed in salivary gland tumors and salivary glands. Therefore, salivary gland neoplasm, and normal salivary gland, possibly demonstrate the accumulation of PSMA in PET/CT. Thus, we need to monitor the side effects in the salivary glands during TAT for prostate cancer.

Mammary Lobular Carcinoma-Like Salivary Gland Carcinoma: Report of a Rare Case

Salivary and mammary glands are both exocrine organs sharing multiple tumorigenic processes. To the best of our knowledge, salivary gland tumors mimicking invasive lobular carcinoma of the breast have not yet been described. Herein, we report a case of a 62-year-old male who presented with progressive facial paralysis. Pathologic examination revealed an ill-defined epithelial neoplasm exhibiting discohesive growth set within an extensively fibrotic stroma. Both perineural and intraneural invasion were present. E-cadherin and p120 immunostaining showed aberrant cytoplasmic expression. Targeted next-generation sequencing detected a frameshift mutation of the CTNNA1 gene as the only known pathogenic variant. The patient was treated with surgical resection, immunotherapy, and chemotherapy. Currently, he is alive with disease twenty months after disease onset.

Salivary duct carcinoma of the submandibular gland presenting a diagnostic challenge: A case report

BACKGROUND

Salivary duct carcinoma (SDC) is a rare, extremely aggressive malignancy that arises in the submandibular gland. It can metastasize locally early and therefore is an important differential diagnosis of metastatic disease in cervical lymph nodes or specific lymphadenitis such as tuberculous cervical lymphadenitis.

CASE SUMMARY

We report a case of SDC in the submandibular gland that presented diagnostic difficulty. The lesion was coincidentally discovered through examination of the radiolucent area of the maxilla. Imaging failed to confirm the possibility of specific inflammation, leading us to execute an open biopsy to verify the diagnosis. The surgical specimen showed that the submandibular gland was primarily replaced with a calcified body. Following histological analysis and confirmation, we performed surgical resection, radiotherapy, and various chemotherapies.

CONCLUSION

Radiographic imaging characteristics of lymph node metastases of salivary gland cancer, especially of SDC, may resemble other cervical lymphadenitis; calcification at the submandibular gland is the landmark of SDC occurring at the subman-dibular gland.

Adjuvant Treatment of the Salivary Duct Carcinoma with Her2 Overexpression

Malignant salivary gland tumors form 11% of all head and neck tumors. Salivary duct carcinoma (SDC) of the parotid gland is an uncommon and highly aggressive tumor accounting for 2% of all salivary gland malignancies. The fourth edition of the WHO Classification of Head and Neck Tumors reported global annual incidence of 0.4–2.6/100,000 people. Standard treatment for SDC is wide surgical resection along with lymph node dissection followed by adjuvant radiation therapy. The role of adjuvant chemotherapy is not known. Here, we present a case of an SDC of the parotid gland in a 55-year-old female. She presented with a painless swelling behind her right ear. Surgery was performed, and total right parotidectomy was done along with selective neck dissection (levels II, III, VA). The pathology report concluded that it was a G3 (poorly differentiated) SDC (micropapillary variant) with lymphovascular and perineural invasion. The clinical stage of the disease was T4aN2bM0. Adjuvant therapy consisted of concurrent radiation (TD 66 Gy) and chemotherapy with weekly paclitaxel (45 mg/m²), carboplatin (AUC 1.5), and trastuzumab (2 mg/kg; THC) for 6 weeks followed by 4 cycles of THC every 3 weeks. Adjuvant trastuzumab was continued for a total of 1 year. She is still without the evidence of the disease 7 years later. The consensus regarding the use of adjuvant chemotherapy does not exist. Based on all the data that have been presented before, the conclusion is that we need new treatment modalities to improve the outome of this aggressive disease.

Successful Treatment with Nivolumab in a Patient with Metastatic Salivary Duct Carcinoma

Salivary duct carcinoma (SDC) is a rare and highly aggressive malignancy. A 58-year-old man presented with a right-sided submandibular mass and metastatic lesions in the right supraclavicular and inferior internal jugular nodes. He underwent right submandibulectomy and right neck dissection followed by adjuvant chemoradiotherapy. However, relapse occurred in the hilar lymph node and lumbar spine. Although radiotherapy was performed, a second relapse appeared in the hilar lymph nodes and sacral bone. Immunohistochemical analysis revealed negativity for programmed death ligand-1 (PD-L1) in the primary tumor specimen. The patient then received the anti-programmed death-1 (PD-1) antibody nivolumab. His metastatic lesions were completely eliminated after 48 weeks of therapy. This case reveals that anti-PD-1 antibodies are effective even against PD-L1-negative SDC.

Primary and Secondary/ Metastatic Salivary Duct Carcinoma Presenting within the Sinonasal Tract

Traditionally, sinonasal adenocarcinomas have been subdivided into intestinal (ITAC) and non-intestinal (non-ITAC) categories. The latter encompasses salivary-type adenocarcinomas originating from the seromucinous glands of the sinonasal mucosa and non-salivary adenocarcinomas. The non-salivary adenocarcinoma category is further subdivided into low-and high-grade variants. Among salivary-type sinonasal adenocarcinomas, tumors recapitulating salivary duct carcinoma (SDC) are exceedingly rare, but some might have been lumped into the high-grade non-ITAC category. To date, only three primary SDCs originating in the sinonasal tract have been reported. We herein describe 7 cases of SDC including one previously reported case (4 primary sinonasal, 3 metastatic/ extension from parotid gland SDC). The primary tumors affected 3 males and one female aged 60 - 75. Different sites were involved by the primary tumors while the secondary tumors affected the sphenoidal (2) and the frontal + maxillary (1) sinuses. Three primary tumors were de novo high-grade SDC and one was confined to contours of a pre-existing pleomorphic adenoma. All 3 secondary tumors were SDC ex pleomorphic adenoma of the parotid with a long history of recurrences, ultimately involving the sinonasal tract. Androgen receptor was positive in 7/7 cases. Four of 6 cases were strongly HER2/neu + (either score 3 + or with verified amplification). This small case series adds to the delineation of primary sinonasal SDC highlighting that almost half of invasive SDC presenting within sinonasal tract indeed represents extension or metastasis from a parotid gland primary. There is a tendency towards overrepresentation of HER2/neu-positive cases in both categories (primary and metastatic), but this needs clarification in larger studies.

Salivary Duct Carcinoma: An Aggressive Salivary Gland Carcinoma with Morphologic Variants, Newly Identified Molecular Characteristics, and Emerging Treatment Modalities

Salivary duct carcinoma (SDC) is a rare, aggressive salivary gland malignancy with significant mortality. Morphologically, most tumors are characterized by apocrine differentiation with a typical immunophenotype of androgen receptor positive/gross cystic disease fluid protein positive/estrogen receptor negative/progesterone receptor negative. Several morphologic variants of SDC exist, representing diagnostic pitfalls. Several differential diagnoses should be considered because prognosis, treatment, and management may be different from SDC. For SDC, current treatment strategies are aggressive and commonly include surgical excision with lymph node dissection and adjuvant radiotherapy. Continued research is examining the utility of androgen deprivation therapy and targeted molecular therapy.

Increased ERBB2 Gene Copy Numbers Reveal a Subset of Salivary Duct Carcinomas with High Densities of Tumor Infiltrating Lymphocytes and PD-L1 Expression

Salivary duct carcinoma (SDC) commonly expresses androgen receptor (AR) and HER2, giving rise to treatment implications. SDC may also express programmed-death-ligand-1 (PD-L1), a predictive marker of response to checkpoint inhibitors. PD-L1 can be associated with genomic instability and high density of tumor infiltrating lymphocytes (TILs). Evaluation of HER2 immunohistochemistry (IHC) in SDC is not standardized, and relationships between ERBB2 copy numbers, PD-L1 expression and TILs in SDC are unknown. We evaluated 32 SDCs for HER2, AR and PD-L1 expression (IHC), ERBB2 status (FISH) and TILs (slide review). HER2 was scored with three different systems (breast, gastric, proposed salivary gland). PD-L1 was evaluated with the combined positive score. Most patients were older men, presenting at advanced clinical stage with nodal or distant metastases. During follow-up (mean 5 years, range 6 months to 21 years), 25 of the 32 patients (78%) died of SDC. We propose a HER2 IHC scoring system which accurately predicts underlying ERBB2 amplification or increased copy numbers in SDC. Most tumors had increased ERBB2 copy numbers (19/32 amplification, 6/32 aneusomy), a finding associated with higher TIL densities (p = 0.045) and PD-L1 expression (p = 0.025). Patients with TILs ≥ 40% had better prognoses (Log-Rank p = 0.013), with TILs being favorable prognosticators in univariate analysis (Hazard ratio: 0.18, p = 0.024). A subset of SDCs with increased ERBB2 copy numbers have higher TILs and PD-L1 expression. TILs ≥ 40% are associated with better prognosis.

The significance of tyrosine kinase receptor B and brain-derived neurotrophic factor expression in salivary duct carcinoma

Salivary duct carcinoma (SDC) is a high-grade salivary gland neoplasm. It may occur de novo or secondarily from pleomorphic adenoma (ex-PA), with secondary development accounting for more than 50% of the cases. In recent years, the expression of tyrosine kinase receptor B (TrkB), which is in the same family as HER2, has been confirmed in various types of carcinomas. However, there are a few studies on SDC. In order to examine the expression and role of TrkB in SDC, we investigated it. Immunohistochemistry was used to detect the expression of TrkB and its ligands, brain-derived neurotrophic factor (BDNF) and neurotrophin-4 (NT-4) in 20 patients with SDC. The mRNA levels of TrkB, BDNF, and NT-4 were analyzed using quantitative polymerase chain reaction. TrkB was negative in 10 cases and positive in 10 cases, BDNF was negative in 11 cases and positive in 9 cases, and NT-4 was positive in all cases. There was a high number of TrkB-positive cases in the pT4 group and The H-score of TrkB was also significantly higher in the stage III and IV groups. There was a high number of BDNF-positive cases in the ex-PA group and Histo-score of BDNF had a trend of high expression in ex-PA. There were no significant differences or correlations in mRNA expression. Our results suggest that TrkB may be involved in SDC tumor growth.

Systemic therapy in the management of recurrent or metastatic salivary duct carcinoma: A systematic review

BACKGROUND

Salivary duct carcinoma (SDC) is an aggressive subtype of salivary gland cancer. Approximately half of SDC patients will develop recurrences or metastases. Therapeutic palliative therapy is therefore often needed. The majority of SDC tumors expresses the androgen receptor (AR) and one-third expresses human epidermal growth factor receptor 2 (HER2), both are potential therapeutic targets. The aim of this paper is to systematically review and summarize the evidence on systemic palliative therapy for SDC and to provide treatment recommendations.

MATERIALS AND METHODS

Electronic libraries were systematically searched with a broad search strategy to identify studies where SDC patients received systemic therapy. Due to the rarity of SDC no restrictions were placed on study designs.

RESULTS

The search resulted in 2014 articles of which 153 were full-text analyzed. Forty-five studies were included in the analysis, which included in total 256 SDC patients receiving systemic therapy. Two phase 2 trials primarily including SDC patients were identified. The majority of the studies were case series or case reports, resulting in an overall low quality of available evidence. Based on studies including ≥ 5 SDC patients, objective responses to HER2 targeting agents were observed in 60-70%, to AR pathway agents in 18-53% and to chemotherapy in 10-50%.

CONCLUSION

For AR or HER2 positive SDC, agents targeting these pathways are the cornerstone for palliative treatment. Regarding chemotherapy, the combination of carboplatin combined with a taxane is best studied. Regarding other targeted agents and immunotherapy evidence is anecdotal, limiting formulation of treatment recommendations for these antineoplastic agents.

A Case of Salivary Duct Carcinoma Intracranial Invasion due to Perineural Invasion Through the Facial Nerve

BACKGROUND

Salivary duct carcinoma (SDC) is a rare parotid tumor that often develops as a rapidly growing mass with a poor prognosis. It has a high rate of distant metastases, sometimes with infiltration along nerves. We describe a case of SDC that originated outside the cranium and extended into the cranium along the path of the facial nerve.

CASE DESCRIPTION

A 74-year-old man underwent magnetic resonance imaging at a local hospital, which revealed a tumor in the left internal acoustic canal; the patient was referred to our department. A left facial schwannoma was suspected, and magnetic resonance imaging was performed again 6 months later. Rapid tumor growth was confirmed, and the tumor was resected. The tumor displayed atypical epithelial cells with comedo necrosis and cribriform structure and was diagnosed as SDC. All residual intracranial tumors were removed using the middle fossa approach. The tumor, which was considered to be a primary tumor, was found near the stylomastoid foramen, and it was removed with the parotid gland. Five months after the initial surgery, metastasis to the trigeminal nerve was observed, and this was removed using a retrosigmoid approach, followed by radiation therapy.

CONCLUSIONS

All 4 surgical specimens of this case were presented, and the path of tumor progression was examined in detail. Although the primary lesion was small, intracranial invasion along the facial nerve occurred. SDC should be considered as a tumor that can extend into the cranium, even with a small primary lesion.

Salivary Duct Carcinoma with Late Distant Brain and Cutaneous Metastasis: A Case Report

Salivary duct carcinoma (SDC) is a rare and highly aggressive salivary gland tumor with poor prognosis, rapid growth, distant metastasis, early regional metastasis, and a high rate of recurrence. The parotid gland is the most common site of involvement, and the lungs and the bones are the most common sites of distant metastasis of SDC. Herein, we present a case of SDC of the parotid gland in a 62-year-old male patient with an unusual metastasis to the skin of the primary site and brain 6 years after primary treatment, which comprised of total parotidectomy and radical neck dissection followed by radiotherapy. It is noteworthy that in few cases of SDC with infiltration, (and not in low-grade intraductal carcinoma of the salivary glands), routine treatment may not suffice, and long-term follow-up is highly recommended.

Clinicopathological study of intraductal carcinoma of the salivary gland, with emphasis on the apocrine type

Intraductal carcinoma (IC) is a rare salivary gland tumor with low- to intermediate-grade cytological features. It is further classified into intercalated duct type and apocrine type based on its distinct histologic and immunohistochemical expression. Conventional salivary duct carcinoma (SDC) is an aggressive carcinoma with high-grade features and is usually associated with poor prognosis. In this study, immunohistochemistry and mutation analyses (including HRAS/PIK3CA mutations, RET rearrangement, and human epidermal growth factor receptor 2 [HER2] amplification) of 9 ICs (including 3 pure ICs, 6 ICs with invasive carcinoma) and 24 conventional SDCs were performed and the results were compared. Four intercalated duct-type cases were positive for SOX10 and S100 and negative for AR; five apocrine-type cases showed opposite results. All five apocrine-type cases had cysts with relatively circumscribed tumor borders and morphologically mimicking breast low-grade ductal carcinoma in situ or papillary carcinoma. RET fusion is detected in half of the 4 intercalated duct-type IC but not in the apocrine-type or conventional SDC. HER2 amplification was only observed in conventional SDC. The monoclonal antibody (clone RBT-NRAS) against NRAS Q61R is a sensitive and specific marker used for detecting HRAS Q61R mutation in the salivary gland tumors. The apocrine-type IC had different cytological grades, distinct tumor growth patterns, and no evidence of low- to high-grade transition, suggesting that apocrine-type IC should be distinguished from apocrine SDC with an in situ component.

The clinicopathological significance of the adipophilin and fatty acid synthase expression in salivary duct carcinoma

Salivary duct carcinoma (SDC) is an aggressive, uncommon tumor histologically comparable to high-grade mammary ductal carcinoma. SDCs are usually androgen receptor (AR)–positive and often HER2-positive. Recently, therapies targeting these molecules for SDC have attracted attention. Lipid metabolism changes have been described in association with biological behavior in various cancers, although no such relationship has yet been reported for SDC. We therefore analyzed the clinicopathological relevance of the immunohistochemical expression of adipophilin (ADP) and fatty acid synthase (FASN), representative lipid metabolism–related proteins, in 147 SDCs. ADP and FASN were variably immunoreactive in most SDCs (both 99.3%), and the ADP and FASN expression was negatively correlated (P = 0.014). ADP-positive (≥ 5%) SDCs more frequently exhibited a prominent nuclear pleomorphism and high-Ki-67 labeling index than those ADP-negative (P = 0.013 and 0.011, respectively). In contrast, a high FASN score, calculated by the staining proportion and intensity, (≥ 120) was correlated with the high expression of AR and FOXA1 (P < 0.001 and = 0.003, respectively). The ADP and FASN expression differed significantly among the subtypes based on biomarker immunoprofiling, as assessed by the AR, HER2, and Ki-67 status (P = 0.017 and 0.003, respectively). A multivariate analysis showed that ADP-positive expression was associated with a shorter overall and progression-free survival (P = 0.018 and 0.003, respectively). ADP was associated with an aggressive histopathology and unfavorable prognosis, and FASN may biologically interact with the AR signaling pathway in SDC. ADP may, therefore, be a new prognostic indicator and therapeutic target in SDC.

Low-grade Apocrine Intraductal Carcinoma: Expanding the Morphologic and Molecular Spectrum of an Enigmatic Salivary Gland Tumor

Intraductal carcinoma (IDC) is the current designation for a salivary gland neoplasm previously referred to as "low-grade salivary duct carcinoma" and "low-grade cribriform cystadenocarcinoma," among others. IDC is conceptually believed to be similar to ductal carcinoma in-situ of the breast. Although IDC is one entity in the current WHO Classification of Head and Neck Tumors, recent studies have suggested that at least three subtypes exist: a low-grade, intercalated duct-like variant with frequent RET rearrangements; a high-grade apocrine variant with complex, salivary duct carcinoma-like genetics; and a mixed variant. We sought to characterize an unusual form of low-grade, purely apocrine IDC. Three cases of apocrine-type IDC with low-grade histology were retrieved from the authors' consultation files. Immunohistochemistry for androgen receptor, GCDFP-15, S100, smooth muscle actin, and p40 was performed. A custom, targeted next generation sequencing (NGS) panel including 1425 cancer-related genes was also done on all cases. All three cases developed in the parotid glands of men, aged 51, 63, and 73 years (mean, 62 years). All cases consisted of large, rounded macrocysts surrounded by smaller nests which were lined by cells with abundant granular eosinophilic cytoplasm and large round nuclei with prominent nucleoli. Pleomorphism was mild, the mitotic rate was low, and necrosis was absent. No cases had any invasive foci or areas of intercalated duct-like morphology. By immunohistochemistry, all cases were diffusely positive for androgen receptor and GCDFP-15, surrounded entirely by an intact layer of small myoepithelial cells positive for S100, smooth muscle actin, and p40. Targeted NGS results were obtained from two cases: both harbored HRAS mutations and copy number losses in TP53, while one case each harbored mutations in PIK3CA, SPEN, and ATM. Fusions were absent in both cases. All three patients were treated by surgery alone, and are currently free of disease (follow up 12-190 months). This study confirms the existence of a low-grade, purely apocrine form of IDC. In its pure form, i.e., without an intercalated duct-type component, low-grade apocrine IDC is genetically similar to high-grade salivary duct carcinoma, with frequent HRAS and PI3K pathway mutations. Despite its molecular similarities to the aggressive salivary duct carcinoma, low-grade apocrine IDC appears to behave in a very indolent manner, supporting is classification as a non-invasive neoplasm, and underscoring the need to distinguish these tumors from each other.

68Ga-PSMA-HBED-CC PET/CT imaging for adenoid cystic carcinoma and salivary duct carcinoma: a phase 2 imaging study

Rationale: Treatment options for recurrent and/or metastatic (R/M) adenoid cystic carcinoma (ACC) and salivary duct carcinoma (SDC), major subtypes of salivary gland cancer, are limited. Both tumors often show overexpression of prostate-specific membrane antigen (PSMA). In prostate cancer, PSMA-ligands labeled with ⁶⁸Ga or ¹⁷⁷Lu are used for imaging and therapy, respectively. Primary aim of this study in R/M ACC and SDC patients was to systematically investigate ⁶⁸Ga-PSMA-uptake by PET/CT imaging to determine if PSMA radionuclide therapy could be a treatment option.

Methods: In a prospective phase II study, PET/CT imaging was performed 1 h post injection of ⁶⁸Ga-PSMA-HBED-CC in 15 ACC patients and 10 SDC patients. Maximum standardized uptake values (SUV) were determined in tumor lesions. Immunohistochemical PSMA expression was scored in primary tumors and metastatic tissue. Standard imaging (MRI or CT) was performed for comparison.

Results: In ACC patients, SUV_max ranged from 1.1 to 30.2 with a tumor/liver-ratio >1 in 13 out of 14 evaluable patients (93%). In SDC patients, SUV_max ranged from 0.3 to 25.9 with a tumor/liver-ratio >1 in 4 out of 10 patients (40%). We found a large intra-patient inter-metastatic variation in uptake of ⁶⁸Ga-PSMA, and immunohistochemistry did not predict ligand uptake in ACC and SDC. Finally, PSMA-PET detected additional bone metastases compared to CT in 2 ACC patients with unexplained pain.

Conclusion: In 93% of ACC patients and 40% of SDC patients we detected relevant PSMA-ligand uptake, which warrants to study PSMA radionuclide therapy in these patients. Additionally, our data provide arguments for patient selection and treatment timing. Finally, PSMA-PET imaging has added diagnostic value compared to CT in selected patients.

Immunohistochemical Reactivity of Prostate-Specific Markers for Salivary Duct Carcinoma

OBJECTIVES

NKX3.1, a transcription factor related to androgen expression, has recently been introduced as a diagnostic marker of prostate adenocarcinoma. Salivary duct carcinoma (SDC) is typically positive for androgen receptor (AR). Therefore, we hypothesized that NKX3.1 is a new immunohistochemical marker for SDC and aimed to investigate whether NKX3.1 staining in combination with other immunomarkers of prostate carcinoma could have a diagnostic or prognostic value in SDC.

METHODS

Materials obtained from 42 resected SDCs were examined by immunohistochemistry using antibodies against AR, NKX3.1, α-methylacyl-CoA racemase (AMACR), prostatic acid phosphatase (PAP), and prostate-specific antigen (PSA).

RESULTS

In immunoreactivity among SDC cases, 81.0, 35.7, 58.5, 33.3, and 0% were positive for AR, NKX3.1, AMACR, PAP, and PSA, respectively. AMACR and PAP immunoreactivity rates were higher in recurrence cases than in cases with no recurrence.

CONCLUSIONS

NKX3.1 expression is useful for SDC diagnosis, but decreased NKX3.1 expression was not correlated with SDC progression. The immunoreactivity of AMACR and PAP could be useful for assessing prognosis in SDC, but immunohistochemical staining of prostate-specific markers should be interpreted with caution when determining whether a metastatic tumor is of prostate origin, especially when patients have a history of SDC.

Salivary Duct Carcinoma of the Submandibular Gland: A Case Report and Review of the Literature

We report a patient who presented with swelling to the left submandibular region. Imaging studies revealed an expansive heterogeneous process. The patient underwent tumor resection and a biopsy confirmed the presence of a salivary duct carcinoma. Additional treatment included chemotherapy and the patient is currently receiving palliative and supportive care for advanced metastatic disease.

Advances and challenges in precision medicine in salivary gland cancer

Salivary gland cancer (SGC) is a rare malignancy consisting of 22 subtypes with different genetic, histological and clinical characteristics. This rarity and heterogeneity makes systemic treatment of recurrent or metastatic (R/M) disease challenging. Use of chemotherapy is scarcely studied and chemotherapy at best has moderate effects. New therapeutic strategies are therefore warranted, but advances made in SGC are lagging behind on advances made in more common cancers. By unraveling tumor characteristics of SGC, such as genetic alterations and protein expression profiles, therapeutic strategies tailored to the patient's tumor can be rationalized. This genomic profiling and mapping of immunohistochemical expression profiles is essential in the search for a suitable treatment approach. Thereby, it alleviates the paucity in systemic treatment options and can significantly alter the prognosis of patients with R/M SGC. This review aims to give a comprehensive overview of known genetic alterations and expression profiles amenable for targeted therapy in every histological subtype of SGC. We discuss the remaining knowledge gaps and the implications of these targets for future studies and personalized treatments, thereby aiding clinicians faced with this rare and heterogeneous type of cancer.

[Clinicopathological analysis of 40 cases of salivary duct carcinoma]

Objective: To investigate the clinical manifestations and pathological changes of salivary duct carcinoma (SDC) and the relationship between them, so as to provide reference for the diagnosis of SDC. Methods: In this retrospective analysis 40 cases of SDC diagnosed from January 2012 to August 2018 in the Department of Pathology of the First Affiliated Hospital of Zhengzhou University were enrolled and the clinical and pathological characteristics were analyzed, 29 were male and 11 were female, the ratio of male to female was 2.64∶1, the median age was 59.0 years, the average course of disease was 3.5 years. The reported cases of SDC were reviewed and compared with patients of this study. Results: Among the 40 patients, 24 cases occurred in parotid gland, 9 cases in submandibular gland and 7 cases in small salivary glands; 24 cases had cancer cell infiltration and invasion of adjacent tissues, 11 cases had lymph node metastasis and 9 cases had distant metastasis at the time of diagnosis. Pathological results showed that 27 cases belonged to primary salivary duct carcinoma, 13 cases belonged to malignant transformation of pleomorphic adenoma; 10 cases invaded local nerve, 22 cases invaded glandular lobules and ducts. Immunohistochemical results showed that 33 cases were positive for androgen receptor, 27 cases were positive for cytokeratin-7, 22 cases were positive for human epidermal growth factor receptor-2, 8 cases were positive for gross cyst disease fluid protein 15. The proliferation index of nuclear antigen Ki-67 ranged from 10% to 90%. Among them 18 cases were over 50% and 22 cases were below 50%. Conclusions: Salivary duct carcinoma is a rare and highly malignant tumor of the salivary gland. Accurate pathological diagnosis is helpful to inhibit the early local recurrence, distant metastasis and improve survival rate of salivary duct carcinoma.

Biomarker immunoprofile and molecular characteristics in salivary duct carcinoma: clinicopathological and prognostic implications

Salivary duct carcinoma (SDC) is one of the most aggressive salivary gland tumors, and prognosis remains poor for most patients. The aim of this study was to investigate the prognostic implications of biomarker immunoprofile in a cohort of SDC and to identify molecular characteristics through next-generation sequencing (NGS) in a subset of cases. Clinicopathological and follow-up information of 25 cases diagnosed as SDC was collected. Immunoexpression of AR, HER-2/neu, GATA3, CK5/6, and MIB1 was analyzed, and ERBB2 (HER-2/Neu) gene amplification was investigated by fluorescence in situ hybridization. Cases were classified under the "SDC revised classification system." Eight SDC cases were analyzed by targeted NGS for detection of gene fusions and variants. Overall survival and disease-free survival were analyzed with Kaplan-Meier curves and Cox regression. Most cases expressed AR (100%), GATA3 (73%), and CK5/6 (76.5%), and 42% expressed HER-2/neu. ERBB2 gene amplification was proven by fluorescence in situ hybridization in 7 of 15 (46%) cases. Apocrine HER2 (AR+/HER2+) subtype was significantly associated with lower overall survival (P = .05). NGS analysis revealed 9 pathogenic mutations in 7 SDC cases, and the most frequently mutated gene was HRAS (4/9) followed by PIK3CA (2/9) and TP53 (2/9). One case (1/9) presented homozygous deletion of locus 9p21 (CDKN2A), and another case (1/9) showed MDM2 amplification. In conclusion, we demonstrated that Apocrine HER2 (AR+/HER2+) is a potential biomarker of poor outcome in SDC. Furthermore, NGS analysis revealed recurrent mutations in SDC.

Androgen receptor immunohistochemistry in salivary duct carcinoma: a retrospective study of 188 cases focusing on tumoral heterogeneity and temporal concordance

Salivary duct carcinoma (SDC) is a high-grade salivary gland carcinoma that is associated with frequent metastasis and poor outcome. Androgen receptor (AR) immunoexpression in SDC is reported in 69% to 100% of SDC. Androgen deprivation therapy (ADT) has shown a response rate of 18% to 42% in SDC. Therefore, AR immunoexpression may serve as a diagnostic and predictive marker for ADT response in SDC. We investigated AR immunopositivity and staining pattern in a large retrospective cohort of 188 SDCs from 163 patients, including 22 paired primary and metastatic SDCs from the same patients, focusing specifically on staining heterogeneity and concordance. A control cohort of 61 non-SDC salivary gland carcinomas was also included. AR immunopositivity defined as ≥1% of tumor cell nuclear staining was found in 94% (177/188) of SDCs, including 95% of primary tumors, 100% of regional metastases, and 90% of distant metastases. Most of the cases (75%, 86/114) showed homogeneous and diffuse AR positivity. However, a subset (25%) exhibited focal or heterogeneous AR staining pattern. Although most metastases (21/22, 95%) had concordant AR expression with the primary tumors, one treatment-naïve tumor (5%) had complete loss of AR immunoexpression in the metastasis without detectable molecular alterations in AR or AR co-regulators. AR positive staining in non-SDC salivary carcinomas was infrequent (15%, 9/61), and mostly heterogeneous or focal. AR immunoexpression is highly prevalent in SDC, in both primary (94%) and metastatic tumors (93%). The cumulative AR immunopositivity rate in SDC is 90% based on data from the current study and previous literature. A small subset may show intratumoral AR heterogeneity and discordant AR expression in metastasis. AR immunoexpression may be seen in non-SDC salivary gland carcinomas but it is uncommon and usually focal.

Immunohistochemical expression of mammaglobin in salivary duct carcinomas de novo and salivary duct carcinoma ex pleomorphic adenoma

Mammaglobin is expressed in breast and salivary gland secretory carcinomas; however, its expression in salivary duct carcinomas (SDCs) still not well established. Therefore, the aim of this study was to investigate the presence and distribution of mammaglobin immunoexpression in SDC ex-PA in different phases of the adenoma to carcinoma sequence evaluating its possible involvement in carcinogenesis and tumor progression, as well as to determine its expression in SDC de novo. Mammaglobin immunohistochemistry was performed in 84 SG tumors, including 41 pleomorphic adenomas (PA) without malignant transformation, 13 intracapsular SDC ex-PA, 5 frankly invasive SDC ex-PA, 25 SDC de novo and 10 secretory carcinomas. The reactions were qualitatively analyzed and digitally scored. Positive immunostaining for mammaglobin was observed in 37 out of 84 SG tumors evaluated (44.1%), but strong staining was consistently seen only in secretory carcinomas, SDC de novo and frankly invasive SDC ex-PA, while it was weaker in intracapsular SDC ex-PA and PA. In PA, mammaglobin expression was significantly associated with recurrence. This study has confirmed that the mammaglobin is commonly expressed in SDC de novo and secretory carcinomas. Its expression was higher in SDC ex-PA than in PA, suggesting that mammaglobin may play a role in its malignant transformation.

Sex disparities in salivary malignancies: Does female sex impact oncological outcome?

OBJECTIVE

Previous population-based studies in salivary gland carcinomas have described a relationship between female sex and superior oncological outcome.

PATIENTS AND METHODS

Our institutional database of 884 surgically treated patients with salivary gland malignancies from 1985 to 2015 was analyzed for the impact of sex on oncological outcomes. Histologies were classified in three risk groups, low, intermediate and high. Survival outcomes were determined using the Kaplan-Meier method. Hazard ratios for male sex were determined using the Cox proportional hazards model.

RESULTS

Eight hundred sixty-seven patients were identified; median age was 59 years, and 51% had a minor salivary gland malignancy. Female patients were younger (58 versus 60 years; p = 0.040) and had a lower incidence of high-risk histologies (25% versus 40%, p < 0.001) and T3-T4 tumors compared to men (23% versus 31%, p < 0.001). With a median follow-up of 57 months, female patients had a superior 5-year disease-specific survival (DSS) (90% versus 79%; p < 0.001). The unadjusted hazard ratio showed male patients had a 2.15-fold increased risk of death (HR 2.15; 95% CI, 1.50-3.06, p < 0.001). After adjusting for Charlson comorbidity index, tobacco use, histological risk group, and overall pathological stage, males still had a statistically significant increased risk of death (HR 1.48; 95% CI 1.05-2.17; p = 0.047). Subgroup analysis showed DSS for females was significantly better in the high-risk histological group (5-year 68% versus 49%, p = 0.007).

CONCLUSION

Our study shows that sex has an impact on cancer-specific survival and that female sex favors improved survival.

Parotid salivary duct carcinoma: a single institution's 20-year experience

Purpose

The aim of the study was to assess the treatment results of the parotid gland salivary duct carcinoma (SDC).

Material and methods

A retrospective clinicopathological analysis of 40 patients treated for parotid SDC in 1996–2015 was performed. The impact of following factors on 5-year disease-free survival (DFS) and overall survival (OS) was studied: age, sex, preoperative 7th nerve palsy, skin infiltration, pT, pN, surgical margin, type of parotidectomy and neck dissection, histology (SDC de novo vs. SDC ex pleomorphic adenoma, SDCexPA), intra/periparotid lymph nodes metastases, perineural invasion (PNI), extraparenchymal extension (EPE), and overexpression HER2.

Results

The average age of the patients was 62 years (ranged from 39 to 81). Males predominated (57.5%). Patients with the clinical stage IV predominated (82.5%). In 1/3 of patients preoperative, 7th nerve palsy occurred. All patients were treated surgically, and all but one had supplementary radiotherapy. In 28 patients (70%), total radical parotidectomy was performed. A neck dissection was performed in all patients. In 19 cases (47.5%), SDCexPA was diagnosed. Negative microscopic surgical margin was obtained in 60% of patients. The follow-up for the whole analyzed group ranged from 2 to 22 years, average was 11.6 years. In 23 patients (57.5%), the disease recurred. Local recurrence was observed in 10 (25%) and distant metastases in 15 (37.5%) cases. 20 patients (50%) died of cancer. 5-year DSF and OS were 42.5% and 41%, respectively. Univariate analysis proved that the significant influence on the survival had 7th nerve palsy (p = 0.024 and p = 0.017, respectively), higher pT-stage (p < 0.001), radical parotidectomy (p = 0.024 and p = 0.022), radical treatment of the neck (p = 0.001 and p = 0.002), EPE (p = 0.040 and p = 0.028), and histology SDCexPA and PNI (p = 0.036 and 0.048). Multivariate analysis showed that independent prognostic factors were the 7th nerve palsy and the histology SDCexPA, which worsened 5-year DFS, respectively, 3.61 and 3.94 times (p = 0.033 and p = 0.026). On the other hand, on 5-year OS, only 7th nerve palsy had an influence (3.86 times worse prognosis, p = 0.033).

Conclusions

SDC is a clinically aggressive cancer with high risk of local recurrence and distant metastases, however, with a chance of curing of around 40%. In the majority of patients, a radical surgical treatment is necessary due to the high clinical stage of disease. Worse prognosis have patients with preoperative 7th nerve palsy and in whom SDC develops in pleomorphic adenoma.

PD-L1 expression by immunohistochemistry in salivary duct carcinoma

BACKGROUND

Immune checkpoint inhibitors play an increasing role in oncologic care. PD-L1 expression is associated with survival and predicts response to PD-1 or PD-L1 inhibitors in a variety of tumors. Our aim is to evaluate the frequency and prognostic significance of PD-L1 expression in salivary duct carcinoma.

DESIGN

We retrospectively evaluated the expression of PD-L1 by two different antibodies (PD-L1 28-8 and PD-L1 22C3) in salivary duct carcinomas. PD-L1 expression in at least 1% of tumor cells was considered immunoreactive. Kaplan-Meier analysis was performed to determine the impact of PD-L1 expression on survival; differences between survival curves were assessed by the chi-square test, and pairwise comparisons of factors were assessed with the log-rank test.

RESULTS

A total of 113 patients' specimens were evaluated. Seventy-six (76%) of the patients were male. Mean age at time of presentation was 61.2 (SD = 12.4) years. PD-L1 expression was found in 26% of the samples. Median follow-up time was 36.6 months (range = 1.4-249 months). Overall survival at 3, 5 and 10 years were 52.6%, 37.9% and 25.6%, respectively. There was no statistical difference in survival between patients with PD-L1-immunoreactive tumors and those without, regardless of which antibody was used (chi² result for all plots: p = 0.53; log rank test for pairwise comparison: p > 0.256).

CONCLUSION

In our analysis, PD-L1 expression occurred in a small proportion of salivary duct carcinomas, usually at low levels, and did not correlate with survival. Its predictive value and utility in selecting patients with salivary duct carcinoma who might benefit from PD-1/PD-L1 inhibitors warrants further investigation.

Salivary Duct Carcinoma of the Parotid Gland Originating from an Epithelial-Myoepithelial Carcinoma: Report of a Rare Case

Salivary duct carcinoma (SDC) is a high-grade carcinoma with poor prognosis, especially among various salivary carcinomas. In this study, we report a rare case of SDC of the parotid gland originating from an epithelial-myoepithelial carcinoma (EMC). A 71-year-old Japanese man presented with swelling of the right parotid region and a right facial nerve paralysis for 10 months. He underwent extended total parotidectomy and chemoradiotherapy after the surgery. Histologically, a major part of the tumor was an androgen receptor (AR)-positive, human epidermal growth factor receptor 2 (HER2)-positive, gross cystic disease fluid protein-15 (GCDFP-15)-positive SDC, with a focus of a typical EMC component at the periphery of the lesion. In the transitional area of the two components, inner ductal cells of double-layered ducts showed similar morphology and immunophenotype to SDC. These findings suggest that SDC originated from the inner ductal cells of EMC. Because the tumor included an EMC as a low-grade carcinoma and an SDC as a high-grade carcinoma, we can consider our case as a dedifferentiated carcinoma as well as a hybrid tumor.