Case report: Salivary duct carcinoma in a patient with a germline CDH1 pathogenic variant - expanding the spectrum of hereditary cancer predisposition syndromes

Introduction

Recently, an entity known as salivary duct carcinoma with rhabdoid features (SDC-RF) has been associated with somatic CDH1 mutations. Here we present the first known case report of conventional SDC occurring in the setting of a germline CDH1 pathogenic variant accompanied by a somatic loss of heterozygosity at the CDH1 locus.

Case discussion

A 67-year-old man presented with chest and back pain and was found to have osteolytic lesions in the sternum and lumbar spine. Vertebral bone biopsies were positive for metastatic carcinoma of unknown primary. A molecular profiling assay consisting of both whole-exome next-generation sequencing (NGS) as well as immunohistochemistry (IHC) for select clinically-relevant proteins performed on the bone biopsy suggested a triple-negative (ER/PR/ERBB2 negative, by IHC), androgen receptor (AR IHC) positive tumor profile. Additionally, the assay uncovered a coding mutation in the CDH1 gene (c.1792C>T, p.R598*) with genomic loss of the second CDH1 allele. Germline testing returned positive for a heterozygous CDH1 pathogenic variant. PET-CT revealed a tumor in the neck suggestive of the primary malignancy consistent with that of salivary gland origin. The patient was initially treated with carboplatin and paclitaxel, then pembrolizumab, and finally with AR-directed therapy using leuprolide and enzalutamide. These treatments were not successful, and the patient eventually succumbed to his disease.

Conclusion

Molecular testing revealed that our patient had bi-allelic inactivation of the CDH1 gene. We believe our patient developed a somatic mutation in addition to his preexisting germline CDH1 mutation that ultimately predisposed him to SDC. While previous studies have found somatic CDH1 pathogenic variants in SDC-RF, our patient was found to have a germline CDH1 pathogenic variant in the setting of conventional SDC, without rhabdoid features. This case provokes questions regarding tumor genetics and molecular profiling of SDC in patients with germline CDH1 pathogenic variants. Moreover, this case supports the notion that SDC may be the salivary counterpart of other malignancies associated with germline CDH1 pathogenic variants and may possibly expand the spectrum of tumors that arise in this familial cancer-predisposition syndrome.

A 22-year single institution review of 119 cases of salivary duct carcinoma

Objective

Salivary duct carcinoma (SDC) is a rare and aggressive salivary gland malignancy. Herein, we present the largest single-institution review of SDC to date.

Methods

This is a retrospective cohort study of all histologically confirmed cases of SDC seen at our institution from January 1, 2002, to August 1, 2022. Patient demographics, treatment, histological characteristics, tumor staging, and outcomes were extracted from the electronic medical record. Kaplan-Meier and Cox regression survival analyses were performed.

Results

This study included 119 patients with a mean age of 66.2 years. Most primary tumors arose from the parotid gland (72.3%), and 23.5% were noted to be carcinoma ex-pleomorphic adenoma. 57.1% of patients presented with regional lymph node metastasis, whereas 23.5% presented with distant disease. Kaplan-Meier analysis demonstrated a 62.4% 5-year overall survival (OS) and a 69.0% 5-year disease-specific survival (DSS). Univariate analyses indicated that presence of regional lymph node disease (p<.001), distant metastasis (p<.001), perineural invasion (p = .027), and lymphovascular invasion (p = .018) were predictive of decreased OS and DSS. Trastuzumab administration was not associated with survival in HER-2-positive patients receiving chemotherapy. Multivariate analyses demonstrated that presence of nodal disease (HR 30.337, 95% CI 2.782-330.851, p = .005) and carcinoma ex pleomorphic adenoma (HR 5.54, 95% CI 1.024-29.933, p = .047) were associated with decreased OS.

Conclusion

Our patients had more favorable survival rates compared to prior studies, which may be due to lower incidence of nodal disease. Factors associated with worse survival included nodal and distant metastases, perineural invasion, lymphovascular invasion, and tumor size.

Level of Evidence

Level 3.

Brain metastases in patients with salivary duct carcinoma: A retrospective study

BACKGROUND

Salivary duct carcinoma (SDC) is a high-grade adenocarcinoma with a 5-year survival rate of 40%. Although drug therapy has improved patients' prognosis, the impact of brain metastasis (BM) remains poorly understood. We aimed to retrospectively examine the incidence of BM in patients with SDC (n = 464) and develop a tool to estimate their prognoses.

METHODS

We retrospectively examined 464 patients with SDC enrolled in a multicenter study. We investigated the incidence of BM, overall survival (OS) rates, and factors affecting prognosis in patients with BM. We also developed an SDC-graded prognostic assessment (GPA) score for disease prognostication.

RESULTS

Sixty-five (14%) patients had BM. The median OS (mOS) was 13.1 months. On univariate and multivariate analyses, factors such as Eastern Cooperative Oncology Group Performance Status >1, human epidermal growth factor receptor 2-negative status, and locoregional uncontrolled disease were associated with poor OS. SDC-GPA scores according to the prognostic factors were 0, 1, 2, and 3 points, and mOS estimates were 50.5, 16.1, 3.9, and 1.2 months, respectively (p < 0.001).

CONCLUSION

The SDC-GPA score emerged as a useful prognostication tool for patients with BM.

Gastric Metastasis from Salivary Duct Carcinoma Mimicking Scirrhous Gastric Cancer

A 59-year-old man underwent submandibular gland excision for salivary duct carcinoma (SDC). One year later, esophagogastroduodenoscopy indicated gastric diffuse mucosal thickening with luminal contraction, mimicking scirrhous gastric carcinoma. Biopsy specimens showed dense proliferation of neoplastic cells expressing androgen receptor and human epidermal growth factor 2, indicating SDC. Gastric diffuse infiltrative metastasis is generally characteristic of gastric metastasis from invasive ductal carcinoma, which shows histologic features similar to SDC. This is the first known report of gastric diffusely infiltrating metastasis in an SDC patient. Rapidly progressing, diffuse gastric wall thickening should also be considered indicative of salivary tumor-associated gastric metastasis.

Analysis of B7-H4 Expression Across Salivary Gland Carcinomas Reveals Adenoid Cystic Carcinoma-Specific Prognostic Relevance

B7-H4 (VTCN1), a member of the B7 family, is overexpressed in several types of cancer. Here we investigated the pattern of expression of B7-H4 in salivary gland carcinomas (SGC) and assessed its potential as a prognostic marker and therapeutic target. Immunohistochemistry (IHC) analyses were performed in a cohort of 340 patient tumors, composed of 124 adenoid cystic carcinomas (ACC), 107 salivary duct carcinomas (SDC), 64 acinic cell carcinomas, 36 mucoepidermoid carcinomas (MEC), 9 secretory carcinomas (SC), as well as 20 normal salivary glands (controls). B7-H4 expression was scored and categorized into negative (<5% expression of any intensity), low (5%-70% expression of any intensity or >70% with weak intensity), or high (>70% moderate or strong diffuse intensity). The associations between B7-H4 expression and clinicopathologic characteristics, as well as overall survival, were assessed. Among all tumors, B7-H4 expression was more prevalent in ACC (94%) compared with those of SC (67%), MEC (44%), SDC (32%), and acinic cell carcinomas (0%). Normal salivary gland tissue did not express B7-H4. High expression of B7-H4 was found exclusively in ACC (27%), SDC (11%), and MEC (8%). In SDC, B7-H4 expression was associated with female gender (P = .002) and lack of androgen receptor expression (P = .012). In ACC, B7-H4 expression was significantly associated with solid histology (P < .0001) and minor salivary gland primary (P = .02). High B7-H4 expression was associated with a poorer prognosis in ACC, regardless of clinical stage and histologic subtype. B7-H4 expression was not prognostic in the non-ACC SGC evaluated. Our comparative study revealed distinct patterns of B7-H4 expression according to SGC histology, which has potential therapeutic implications. B7-H4 expression was particularly high in solid ACC and was an independent prognostic marker in this disease but not in the other SGC assessed.

TRPS1 immunohistochemical expression in salivary gland tumors: A pilot study

OBJECTIVES

TRPS1 is a new, sensitive marker for breast carcinoma (BC). Salivary glands and breasts are both exocrine glands; thus, their tumors may share similar morphology and immunophenotype. Among salivary gland-type BC, TRPS1 is reported to be positive in secretory carcinomas (SCs) but negative in acinic cell carcinomas (AciCCs) and most adenoid cystic carcinomas (AdCCs). A subset of salivary duct carcinomas (SDCs) is positive for TRPS1. Herein, we investigate TRPS1 immunohistochemical expression in salivary gland tumors (SGTs).

METHODS

A retrospective search yielded 110 SGTs (97 primary and 13 metastatic). TRPS1 immunohistochemistry was scored as negative, low positive, intermediate positive, or strongly positive.

RESULTS

TRPS1 was expressed in 78% (14/18) of pleomorphic adenoma (PA) cases but negative/low positive in all Warthin tumors (6/6 [100%]). In basal cell adenoma (BCA), TRPS1 expression was intermediate to strong (13/14 [92%]) in the stromal cells, whereas ductal or basal cells showed low expression. TRPS1 expression varied in malignant SGTs, with intermediate to strong staining in 100% (15/15) of AdCCs, 100% (5/5) of basal cell adenocarcinoma, 100% (3/3) of intraductal carcinoma, 89% (8/9) of polymorphous adenocarcinoma, and 89% (7/8) of SDCs; negative/low positive expression was observed in 100% (3/3) of SCs, 89% (8/9) of AciCCs, and 50% (3/3) of mucoepidermoid carcinomas. In addition, strong and intermediate TRPS1 expression was observed in metastatic SGT to the lungs, lymph nodes, and soft tissue.

CONCLUSIONS

Overall, TRPS1 is strongly expressed in PA as well as malignant and metastatic SGT. In addition, TRPS1 is positive in stromal cells of BCA but negative or low positive in ductal and basal cells.

A phase 2 multicenter study of docetaxel-PM and trastuzumab-pkrb combination therapy in recurrent or metastatic salivary gland carcinomas

BACKGROUND

Salivary duct carcinoma (SDC) is uncommon but is the most aggressive subtype of salivary gland carcinomas. The high positivity rate for human epidermal growth factor receptor 2 (HER2) led to an investigation of the efficacy of HER2-targeted agents. Docetaxel-PM (polymeric micelle) is a low-molecular-weight, nontoxic, biodegradable, and docetaxel-loaded micellar formulation. Trastuzumab-pkrb is a biosimilar to trastuzumab.

METHODS

This was a multicenter, single-arm, open-label phase 2 study. Patients with HER2-positive (immunohistochemistry [IHC] score of ≥2+ and/or HER2/chromosome enumeration probe 17 [CEP17] ratio of ≥2.0) advanced SDCs were enrolled. Patients received docetaxel-PM (75 mg/m2 ) and trastuzumab-pkrb (8 mg/kg in the first cycle and 6 mg/kg in subsequent cycles) every 3 weeks. Primary end point was objective response rate (ORR).

RESULTS

A total of 43 patients were enrolled. The best objective responses were partial response in 30 (69.8%) patients and stable disease in 10 (23.3%) patients, leading to an ORR of 69.8% (95% confidence interval [CI], 53.9-82.8) and a disease control rate of 93.0% (80.9-98.5). Median progression-free survival, duration of response, and overall survival were 7.9 (6.3-9.5), 6.7 (5.1-8.4), and 23.3 (19.9-26.7) months, respectively. Patients with HER2 IHC score of 3+ or HER2/CEP17 ratio ≥2.0 demonstrated better efficacies compared to those with HER2 IHC score of 2+. Thirty-eight (88.4%) patients experienced treatment-related adverse events (TRAE). Because of TRAE, nine (20.9%), 14 (32.6%), and 19 (44.2%) patients required temporary discontinuation, permanent discontinuation, or dose reduction, respectively.

CONCLUSIONS

The combination of docetaxel-PM and trastuzumab-pkrb demonstrated promising antitumor activity with a manageable toxicity profile in HER2-positive advanced SDC.

PLAIN LANGUAGE SUMMARY

Salivary duct carcinoma (SDC) is uncommon but is the most aggressive subtype of salivary gland carcinomas. SDC shares morphological and histological similarities with invasive ductal carcinoma of breast, which led to an investigation of hormonal receptor and human epidermal growth factor receptor 2 (HER2)/neu expression status in SDC. In this study, patients with HER2-positive SDC were enrolled and treated with combination of docetaxel-polymeric micelle and trastuzumab-pkrb. Promising antitumor activities were shown with objective response rate of 69.8%, disease control rate of 93.0%, median progression-free survival of 7.9 months, median duration of response of 6.7 months, and median overall survival of 23.3 months.

ERBB2 Amplification and HER2 Expression in Salivary Duct Carcinoma: Evaluation of Scoring Guidelines and Potential for Expanded Anti-HER2 Therapy

Salivary duct carcinoma (SDC) is aggressive with limited therapeutic options. A subset of SDC display human epidermal growth factor receptor 2 (HER2) protein overexpression by immunohistochemistry, and some show ERBB2 gene amplification. Guidelines for HER2 scoring are not firmly established. Recent advances in breast carcinoma have established a role for anti-HER2 therapies in lesions with low HER2 expression lacking ERBB2 amplification. Delineating HER2 staining patterns in SDC is critical for evaluating anti-HER2 treatments. In total, 53 cases of SDC resected at our institution between 2004 and 2020 were identified. Androgen receptor (AR) and HER2 immunohistochemistry and ERBB2 fluorescence in situ hybridization were performed in all cases. AR expression was scored for percentage positive cells and categorized as positive (>10% of cells), low positive (1%-10%), or negative (<1%). HER2 staining levels and patterns were recorded, scored using 2018 ASCO/CAP guidelines, and categorized into HER2-positive (3+ or 2+ with ERBB2 amplification), HER2-low (1+ or 2+ without ERBB2 amplification), HER2-very low (faint staining in <10% of cells), or HER2-absent types. Clinical parameters and vital status were recorded. Median age was 70 years, with a male predominance. ERBB2-amplified tumors (11/53; 20.8%) presented at lower pT stages (pTis/pT1/pT2; P = .005, Fisher exact test) and more frequently had perineural invasion (P = .007, Fisher exact test) compared with ERBB2 nonamplified tumors; no other pathologic features differed significantly by gene amplification status. In addition, 2+ HER2 staining by 2018 ASCO/CAP criteria was most common (26/53; 49%); only 4 cases (8%) were HER2-absent status; 3+ HER2 staining was found in 9 tumors, and all were ERBB2 amplified. Six patients with HER2-expressing tumors received trastuzumab therapy, including 2 with ERBB2-amplified tumors. Overall survival and recurrence-free survival did not differ significantly based on ERBB2 status. This work suggests that 2018 ASCO/CAP guidelines for HER2 evaluation in breast carcinoma could be applied to SDC. Our findings also show broad overexpression of HER2 in SDC raising the possibility that more patients may benefit from anti-HER2-directed therapies.

Salivary Duct Carcinoma with Rhabdoid Features of the Parotid Gland with No E-Cadherin Expression: A Report with Anti-HER2 Therapy and Review of the Literature

Salivary duct carcinoma with rhabdoid features (SDC-RF) is a rare form of salivary gland neoplasm that was recently described. We report a case of SDC-RF of the parotid gland with loss of E-cadherin and decreased β-catenin expression in a 73-year-old male who presented with right facial/neck swelling and intermittent pain. Morphologically, the tumor presented with a discohesive infiltrate of isolated and cords of pleomorphic round cells containing moderate amount of eosinophilic to fine-vacuolated cytoplasm and hyperchromatic nuclei infiltrating through fibroadipose tissue and salivary parenchyma. Immunophenotypically, the tumor was positive for Cytokeratins Oscar and 7, GATA3, GCDFP, HER2, and an androgen receptor but negative for CK20, S100, p40, Melan A, CDX2, TTF1, ER, SATB2, DOG1, synaptophysin, and chromogranin. Due to its diffuse infiltrating pattern, involvement of the parapharyngeal space, supraclavicular fat pad, dermis, and skin without a defined surgical target, the tumor was deemed unresectable. Anti-HER2 therapy (Herceptin and Pertuzumab) was utilized. At the last follow-up, the patient is alive, with complete locoregional control and brain metastases. An electronic search was performed in the following registries for papers published up to June 2023: PubMed, Embase, and Web of Science. For the database searches, the keywords searched were "salivary gland", "salivary duct carcinoma", and "salivary duct carcinoma with rhabdoid features". Our review of the literature identified 30 cases of SDC-RF that reveal there is a predilection for males (83%), parotid gland (72%), and patients older than the 6th decade of life (83%). Immunophenotypically, all SDC-RF cases except one were positive for AR and GCDFP (97%), 81% were positive for HER2, and loss or decreased expression of E-cadherin in 93% of cases. In conclusion, we described a rare case of SDF-RF of the parotid gland with no E-cadherin expression, decreased β-catenin expression, and its immunophenotypic profile.

Targeted treatment in a case series of AR+, HRAS/PIK3CA co-mutated salivary duct carcinoma

Background and purpose

A subgroup of salivary duct carcinoma (SDC) harbor overexpression of the androgen receptor (AR), and co-occurring mutations in the HRAS- and PIK3CA-genes. The impact of genomic complexity on targeted treatment strategies in advanced cancer is unknown.

Materials and methods

We analyzed molecular and clinical data from an institutional molecular tumor board (MTB) to identify AR+, HRAS/PIK3CA co-mutated SDC. Follow-up was performed within the MTB registrational study or retrospective chart review after approval by the local ethics committee. Response was assessed by the investigator. A systematic literature search was performed in MEDLINE to identify additional clinically annotated cases.

Results

4 patients with AR+ HRAS/PIK3CA co-mutated SDC and clinical follow-up data were identified from the MTB. An additional 9 patients with clinical follow-up were identified from the literature. In addition to AR overexpression and HRAS and PIK3CA-alterations, PD-L1 expression and Tumor Mutational Burden > 10 Mutations per Megabase were identified as additional potentially targetable alterations. Among evaluable patients, androgen deprivation therapy (ADT) was initiated in 7 patients (1 Partial Response (PR), 2 Stable Disease (SD), 3 Progressive Disease (PD), 2 not evaluable), tipifarnib was initiated in 6 patients (1 PR, 4 SD, 1 PD). One patient each was treated with immune checkpoint inhibition (Mixed Response) and combination therapies of tipifarnib and ADT (SD) and alpelisib and ADT (PR).

Conclusion

Available data further support comprehensive molecular profiling of SDC. Combination therapies, PI3K-inhibitors and immune therapy warrant further investigation, ideally in clinical trials. Future research should consider this rare subgroup of SDC.

Effect of HER2-targeted therapy on PDX and PDX-derived organoids generated from HER2-positive salivary duct carcinoma

BACKGROUND

We previously established a patient-derived xenograft (PDX) model, patient-derived organoids (PDOs), and PDX-derived organoids (PDXOs) for salivary duct carcinoma (SDC). Using these models, this study examined the therapeutic effect of human epidermal growth factor receptor 2 (HER2) blockade on HER2-positive SDC.

METHODS

The therapeutic effect of lapatinib was assessed in SDC PDXOs with regards to cell growth, receptor/downstream signaling molecule expression, phosphorylation levels, and apoptosis. Effect of lapatinib treatment was evaluated in vivo in SDC PDX mice.

RESULTS

The siRNA knockdown of HER2 and lapatinib suppressed cell proliferation in SDC PDXOs. Lapatinib inhibited the phosphorylation of HER2 and its downstream targets, and induced apoptosis in SDC PDXOs. Lapatinib also significantly reduced tumor volumes compared with that of the control in SDC PDX mice.

CONCLUSION

For the first time, we demonstrated the efficacy of anti-HER2 therapy in HER2-positive SDC using preclinical models of SDC PDX and PDXO.

Salivary Duct Carcinoma Originated from the Inferior Turbinate: A Rare Case Report

Salivary duct carcinoma (SDC) is an uncommon but highly aggressive tumor with a poor prognosis. SDC mainly arises from the major salivary glands, typically the parotid gland. Here, we report a rare case of sinonasal SDC in a 54-year-old male patient that might have originated from the inferior turbinate. The patient presented with left nasal congestion and rhinorrhea. Following an endoscopic intervention, the histopathological examination revealed a diagnosis of SDC, characterized by the formation of solid cancer nests and central comedo-type necrosis. Given the highly aggressive nature and unfavorable prognosis of SDC, it is essential to consider it as a differential diagnosis for unilateral nasal tumors.

A molecular guide to systemic therapy in salivary gland carcinoma

Salivary gland carcinomas (SGC) are a rare and variable group of head and neck cancers with historically poor response to cytotoxic chemotherapy and immunotherapy in the recurrent, advanced, and metastatic settings. In the last decade, a number of targetable molecular alterations have been identified in SGCs including HER2 upregulation, androgen receptor overexpression, Notch receptor activation, NTRK gene fusions, and RET alterations which have dramatically improved treatment outcomes in this disease. Here, we review the landscape of precision therapy in SGC including current options for systemic management, ongoing clinical trials, and promising future directions.

Role of HER2 in Prognosis of Salivary Duct Carcinoma: A Systematic Review and Meta-Analysis

OBJECTIVES

Salivary duct carcinoma (SDC) is a rare, aggressive malignancy with a poor prognosis. These tumors frequently stain positive for HER2/ErbB2, but data on the prognostic significance of HER2 status in SDC are mixed. We sought to determine whether HER2 status affects survival outcomes in SDC.

METHODS

PubMed, Embase, and Web of Science databases were searched from inception to October 2020. Eligibility was restricted to studies reporting HER2/ErbB2 overexpression in histologically confirmed de novo SDC or SDC ex pleomorphic adenoma, with corresponding overall (OS) and disease-free (DFS) survival measures. Separate multivariable and univariable meta-analyses were performed using random-effects models. Statistical heterogeneity was estimated by Cochran's Q and I² tests. Funnel plots were generated and Egger's test was used to assess for publication bias. The risk of bias was assessed with the Newcastle-Ottawa Scale.

RESULTS

Of 183 unique citations, 14 studies of 663 patients were included. Most included studies determined HER2 status according to ASCO/CAP guidelines. The univariable meta-analysis did not reveal an effect between HER2 status and OS (HR 1.09, 95% CI 0.84-1.42). In the multivariable analysis, HER2 positivity was associated with a HR of 1.49 for OS (95% CI 0.96-2.30). Fewer studies reported data for DFS than OS, with no relationship between HER2 status and DFS found on multivariable or univariable meta-analyses.

CONCLUSION

In patients with salivary duct carcinoma, HER2 positivity was not found to be associated with worse overall survival. This information may be useful when counseling patients and considering treatment options. Laryngoscope, 133:476-484, 2023.

Patterns of Lymph Node Metastasis in Parotid Cancer and Implications for Extent of Neck Dissection

OBJECTIVE

The role and extent of neck dissection in primary parotid cancer are controversial. Herein, we characterize patterns of lymph node metastasis in parotid cancer.

STUDY DESIGN

Retrospective analysis.

SETTING

National Cancer Database.

METHODS

Patients with the 6 most common histologic subtypes of parotid cancer were selected. Primary outcomes were the distribution of positive lymph nodes by level and overall survival assessed by Cox analysis. Secondary outcomes included predictors of extended lymph node involvement (≥3 lymph nodes or Level IV/V involvement), via logistic regression.

RESULTS

Six thousand nine hundred seventy-seven patients with acinic cell carcinoma, adenocarcinoma, adenoid cystic carcinoma, carcinoma ex pleomorphic adenoma (CExPA), mucoepidermoid carcinoma, and salivary duct carcinoma (SDC) were included. Among cN0 patients, 8.2% of low-grade tumor patients had occult nodal metastasis versus 30.9% in high-grade tumor patients. Elective neck dissection was not associated with an overall survival benefit (adjusted hazard ratio: 1.10; 0.94-1.30, p = .238). Among cN+ tumors, CExPA (odds ratio [OR]: 1.88, 1.05-3.39, p = .034) and high-grade pathology (OR: 3.03, 1.87-4.93, p < .001) were predictive of having ≥3 pathologic nodes. CExPA (OR: 2.13, 1.22-3.72, p = .008), adenocarcinoma (OR: 1.60, 1.11-2.31, p = .013), SDC (OR: 1.92, 1.17-3.14, p < .01), and high-grade pathology (OR: 3.61, 2.19-5.97, p < .001) were predictive of Level IV/V neck involvement.

CONCLUSIONS

In parotid malignancy, nodal metastasis distribution is dependent on histology and grade. High-grade tumors and certain histologies (SDC and adenocarcinoma) had a higher incidence of occult nodes. Comprehensive neck dissection should also be considered for node-positive high-grade tumors, SDC, and adenocarcinoma.

HER2 status in recurrent/metastatic androgen receptor overexpressing salivary gland carcinoma patients

Background

Overexpression of human epidermal growth factor receptor type 2 (HER2) occurs in almost 25-30% of androgen receptor (AR)-positive salivary gland carcinomas (SGCs), notably salivary duct carcinoma (SDC) and adenocarcinoma not otherwise specified (NOS). In the last years, several studies have reported the clinical benefit of HER2 directed therapies in this setting. This work aims at describing the natural history of AR-positive recurrent/metastatic (R/M) SGC patients, based on HER2 amplification status.

Methods

Consecutive R/M AR-positive SGC patients accessing our Institution from 2010 to 2021 were analyzed. Descriptive statistics and survival analyses were performed to present the clinical characteristics of the selected patients and the outcomes, based on HER2 status. A specific focus was dedicated to patients developing metastases to the central nervous system (CNS).

Results

Seventy-four R/M AR-positive SGC patients (72 men) were analyzed. Median follow-up was 36.18 months (95% CI 30.19-42.66). HER2 status was available in 62 cases (84%) and in 42% the protein was overexpressed (HER2+). Compared with patients with HER2- SGCs, in patients with HER2+ disease, HR for disease recurrence was 2.97 (95% CI 1.44-6.1, p=0.003), and HR for death from R/M disease was 3.22 (95% CI 1.39-7.49, p=0.007). Moreover, the HER2+ group showed a non-significant trend towards a higher prevalence of CNS metastases (40% vs. 24%, p=0.263). Patients developing CNS metastases had shorter survival than those who did not; at bivariate analysis (covariates: CNS disease and HER2 status), HER2 status demonstrated its independent prognostic significance.

Discussion

In our patient population, HER2 amplification was a negative prognostic factor, and it was associated with a non-statistically significant higher risk of developing CNS metastasis. Further studies are needed to explore the potential clinical benefit of tackling the two biological pathways (AR and HER2) in patients affected by this rare and aggressive malignancy.

Survival benefit of HER2-targeted or androgen deprivation therapy in salivary duct carcinoma

Background

The efficacy and safety of human epidermal growth factor receptor 2 (HER2)-targeted therapy and androgen deprivation therapy (ADT) for locally advanced or recurrent or metastatic (LA/RM) salivary duct carcinoma (SDC) have been reported in prospective studies. However, the survival benefit of these therapies to conventional therapy remains controversial, and whether HER2-targeted therapy or ADT should be chosen in HER2- and androgen receptor (AR)-positive SDC patients remains unknown.

Methods

Overall, 323 LA/RM SDC patients treated at seven institutions between August 1992 and June 2020 were retrospectively enrolled. The primary aim was to analyze the effect of HER2-targeted therapy and ADT on overall survival from the diagnosis of LA/RM disease to death from any cause (OS1). The secondary indicators included the overall response rate (ORR), clinical benefit rate (CBR), overall survival from therapy initiation for LA/RM disease (OS2), progression-free survival (PFS), time to second progression (PFS2), duration of response (DoR), and duration of clinical benefit (DoCB) of HER2-targeted therapy or ADT as first-line therapy for HER2-positive/AR-positive SDC.

Results

Patients treated with HER2-targeted therapy or ADT had longer OS1 than those treated without these therapies (Median OS1: historical control, 21.6 months; HER2-targeted therapy, 50.6 months; ADT, 32.8 months; HER2-targeted therapy followed by ADT, 42.4 months; and ADT followed by HER2-targeted therapy, 45.2 months, p < 0.001). Among HER2-positive/AR-positive SDC patients, although HER2-targeted therapy had better ORR, CBR, and PFS than those of ADT as first-line therapy, we found no significant differences between HER2-targeted therapy and ADT regarding OS2, PFS2, DoR, and DoCB.

Conclusion

Patients treated with HER2-targeted therapy and ADT showed longer survival in LA/RM SDC. HER2-targeted therapy can be recommended prior to ADT for HER2-positive/AR-positive SDC. It is warranted to establish a biomarker that could predict the efficacy of clinical benefit or better response in ADT.

Cystic Salivary Duct Carcinoma Penetrated by Facial Nerve

Salivary duct carcinoma is a rare malignant salivary gland tumor that mainly has solid features. When it occurs in the parotid gland, it can invade the facial nerve and cause facial nerve paralysis. However, in our case, the salivary duct carcinoma exhibited cystic features on computed tomographic imaging, and the facial nerve passed through the cyst. Total parotidectomy with level-I to -III dissections was performed and nerve passing through the tumor was sacrificed. The patient received postoperative radiotherapy and was clinically and radiologically followed-up for every 3 months. Recurrence or distant metastasis was not reported. To the best of our knowledge, this is the first case involving a salivary duct carcinoma with cystic features and facial nerve invasion. Here, we report a first case of cystic salivary duct carcinoma of the parotid gland which uncommonly undergo cystic change and penetrated by facial nerve and successfully resected without causing facial nerve injury.

The implicated clinical factors for outcomes in 304 patients with salivary duct carcinoma: Multi-institutional retrospective analysis in Japan

Background

Salivary duct carcinoma (SDC) is a high‐grade salivary malignancy that frequently occurs as the carcinomatous component of carcinoma ex pleomorphic adenoma. We herein examined the clinical factors affecting outcomes in a large cohort of SDC.

Methods

We selected 304 SDC cases and investigated clinical characteristics and the factors affecting outcomes.

Results

The median age of the cases examined was 68 years, the most common primary site was the parotid gland (238 cases), and there was a male predominance (M/F = 5:1). Outcomes were significantly worse when the primary tumor site was the minor salivary glands (SG) than when it was the major SG. Outcomes were also significantly worse in pN(+) cases (161 cases) than in pN0 cases, particularly those with a metastatic lymph node number ≥11. The cumulative incidence of relapse and distant metastases was significantly higher in stage IV cases than in stage 0–III cases.

Conclusions

The absolute number of lymph node metastases, higher stages, and the minor SG as the primary tumor site were identified as factors affecting the outcome of SDC.

Salivary duct carcinoma: A report of 70 FNA cases and review of the literature

BACKGROUND

Although usually recognized as malignant, fine-needle aspiration (FNA) biopsy of salivary duct carcinoma (SDC) has been confused with other primary salivary gland (SG) neoplasms. This article undertook an analysis of a large collection of SDC FNA cases to assess diagnostic accuracy, specificity, and cytopathology.

METHODS

Cytopathology files were searched for SDC with histopathologic validation. FNA biopsy smears were performed using standard techniques.

RESULTS

Seventy cases from 56 patients (M:F, 1.9:1; age range, 26-92 years; mean age, 65 years) met inclusion criteria. All had tissue confirmation of SDC. FNA sites included: parotid gland (42, 60% cases), neck (10), submandibular gland (7), pre-/post-auricular area (5), face/cheek (3), mediastinal lymph nodes (2), and clavicle (1). Aspirates were from primary (52, 74%), metastatic (12, 17%), and locally recurrent (6, 9%) neoplasms. FNA diagnoses included: SDC (19, 27%), favor/suspicious for SDC (7, 10%), high-grade carcinoma (11), adenocarcinoma (9), carcinoma (6), malignant (6), SG neoplasm (5), atypia (3), SDC versus another malignancy (2), and pleomorphic adenoma (2). Large polygonal cells in groups and single forms showed cribriforming, variable necrosis, pseudopapillae, and oncocytic change. Androgen receptor staining was positive in all cases.

CONCLUSIONS

FNA biopsy is accurate and reliable in classifying SDC as a malignant neoplasm, but much less so for identification as a specific tumor type. Using the Milan system, 86% of aspirates were classified as either malignant or suspicious for malignancy. A recurring pitfall includes sampling error in cases of SDC ex pleomorphic adenoma.

Evaluation of the Clinical Utility of Genomic Profiling to Inform Selection of Clinical Trial Therapy in Salivary Gland Cancer

For most patients with salivary gland cancer, there are no effective standard systemic therapies. Although clinical trials of biomarker-led drug therapies have delivered significant recent advances, there remains a need to understand the clinical utility of genomic profiling of cancer as a means to match patients with recurrent or metastatic salivary gland cancer to clinical trial therapies. In total, 209 patients with salivary gland cancers were profiled with 24 gene (n = 209)) and >325 gene (n = 32) DNA-based next-generation sequencing panels. A retrospective systematic evaluation was performed to identify the frequency of available matched drug therapies within clinical trials based on the results. The matches were then stratified based upon the level of evidence supporting the drug−biomarker combination being investigated using the ESMO Scale for Clinical Actionability of Molecular Targets (ESCAT) to determine the strength of the clinical rationale for each gene−drug match identified. DNA-based next generation sequencing (NGS) analysis was successful in 175/209 (84%) patients with salivary gland cancer. Using the 24-gene NGS panel, actionable alterations were identified in 27% (48/175) patients. Alterations were most frequent in salivary duct carcinoma (88%) characterized by TP53 and/or PIK3CA mutations, with matched trials available for 63% (10/16). In ACC, biomarker-matched trials were available for 7% (8/115), and no genomic alterations were found in 96/115 (83%) of ACC patients. TP53 was the most frequently altered gene across all subtypes; however, there were no trials recruiting based on TP53 status. In 32 ACC patients with no genomic alterations using the 24-gene panel, a broader (>325 gene) panel identified alterations in 87% (27/32) of cases with biomarker-matched trials available in 40% (13/32) cases. This study identified that genomic profiling using focused (24-gene) NGS panels has potential utility in matching to trial therapies for most patients with non-ACC salivary gland cancer. For patients with ACC, broader genomic profiling has demonstrated added clinical utility. We describe the application of an approach to classification of levels of evidence which may be helpful to inform the clinician and patient decision making around the selection of clinical trial therapies.

Nonconvulsive Status Epilepticus Caused by Cerebrospinal Fluid Dissemination of a Salivary Duct Carcinoma: A Case Report

Salivary duct carcinoma (SDC) is a rare and highly aggressive salivary gland tumor with rapid growth, distant metastasis, and a high recurrence rate. Moreover, the parotid gland is the most common site with a poor prognosis. A lower frequency of distance metastasis to the liver, skin, and brain has also been reported, although the lungs, bones, and lymph nodes are the most common sites of SDC metastasis. We report a case of nonconvulsive status epilepticus (NCSE) in a 73-year-old male comatose patient having SDC of the parotid gland with an unusual metastasis to the skin and brain diagnosed by frequent cerebrospinal fluid examinations. Meningeal carcinomatosis usually has a poor prognosis, and NCSE is a reversible cause of altered mentation. Clinicians should know the unique set of epilepsy etiologies in patients with malignant tumors.

[Salivary duct carcinoma in the inferior turbinate: a case report]

Salivary duct carcinoma（SDC） is an uncommon malignant tumor, which occurs rarely in the inferior turbinate. This study present a rare case of a 75-year-old man with right-sided nasal obstruction and rhinorrhagia. The patient elected to have a local excision of the lesion. Histopathology and immunohistochemistry confirmed sinonasal SDC. The patient gave up further treatment. SDC characterized by aggressive behavior and poor prognosis, it is a extremely rare but important differential to consider in patients with unilateral nasal mass.

Case Report: Two Cases of Salivary Duct Carcinoma in Workers With a History of Chromate Exposure

Background: Salivary duct carcinoma (SDC), one subtype of the 22 different salivary gland cancers, is a rare malignancy. Risk factors for the development of salivary gland cancer and SDC are largely unknown, although pollution has been described as one of the risk factors. In other cancers, especially in lung cancer, the carcinogenicity of chromium VI [Cr(VI)] is well-known. Here we report on two SDC patients who were occupationally exposed to Cr(VI) and discuss a potential relation between their Cr(VI) exposure and the occurrence of SDC. Case Presentation: The work history of two SDC patients was analyzed for chemical exposures. Both patients had a history of Cr(VI) exposure, with maintenance of military equipment considered as the source for this exposure. Inhalation of Cr(VI) containing particles from the removal of old paint by mechanical abrasion was identified as a probable source of exposure for both patients, and one of these patients also applied new paint. Both patients reported not to have used any respiratory protection which may have resulted in substantial inhalation of Cr(VI)-containing chromates. Furthermore, in one patient inhalation of fumes from soldering may have resulted in relevant co-exposure. Conclusion: A causal relation between Cr(VI) exposure and SDC, a rare cancer, cannot be demonstrated on an individual basis but detection in a population-based study is also unlikely because of the extremely low prevalence. Nevertheless, the work history is considered a relevant risk factor in the onset of SDC as occupational exposures to Cr(VI) occurred in poorly ventilated working environment and without using appropriate respiratory protective equipment.

Hybrid Carcinoma of the Parotid Gland: An Extremely Rare Three Cases with an Immunohistochemical Analysis and a Review of the Literature

Salivary hybrid carcinoma (HC) is defined as when two or more kinds of carcinoma exist at the same location in a single mass. We reestimated and examined three cases of salivary gland HC. Case 1 involved a 76-year-old male. Case 2 involved a 74-year-old female. Case 3 involved a 66-year-old male. Histologically, case 1 involved a combination of salivary duct carcinoma (SDC) and squamous cell carcinoma (SqCC). Immunohistochemically, the former was positive for gross cystic disease fluid protein (GCDFP)-15 and androgen receptor (AR). Case 2 involved a combination of SqCC and neuroendocrine carcinoma. Immunohistochemically the latter was positive for synaptophysin and neural cell adhesion molecule (NCAM). Case 3 involved a combination of SDC and epithelial-myoepithelial carcinoma (EMC). Immunohistochemically, the former was positive for GCDFP-15 and AR, whereas the inner cells of the latter were positive for cytokeratin 7, and the outer cells of the latter were positive for actin. Because of the transitional zone between SDC and EMC, it was speculated that high-grade SDC arose from low-grade EMC.

Contribution of pre-existing neoantigen-specific T cells to a durable complete response after tumor-pulsed dendritic cell vaccine plus nivolumab therapy in a patient with metastatic salivary duct carcinoma

Although immune checkpoint inhibitors (ICIs) have emerged as new therapeutic options for refractory cancer, they are only effective in select patients. Tumor antigen-pulsed dendritic cell (DC) vaccine therapy activates tumor-specific cytotoxic T lymphocytes, making it an important immunotherapeutic strategy. Salivary ductal carcinoma (SDC) carries a poor prognosis, including poor long-term survival after metastasis or recurrence. In this study, we reported a case of refractory metastatic SDC that was treated with a tumor lysate-pulsed DC vaccine followed by a single injection of low-dose nivolumab, and a durable complete response was achieved. We retrospectively analyzed the immunological factors that contributed to these long-lasting clinical effects. First, we performed neoantigen analysis using resected metastatic tumor specimens obtained before treatment. We found that the tumor had 256 non-synonymous mutations and 669 class I high-affinity binding neoantigen peptides. Using synthetic neoantigen peptides and ELISpot analysis, we found that peripheral blood mononuclear leukocytes cryopreserved before treatment contained pre-existing neoantigen-specific T cells, and the cells obtained after treatment exhibited greater reactivity to neoantigens than those obtained before treatment. Our results collectively suggest that the rapid and long-lasting effect of this combination therapy in our patient may have resulted from the presence of pre-existing neoantigen-specific T cells and stimulation and expansion of those cells following tumor lysate-pulsed DC vaccine and ICI therapy.

Salivary Duct Carcinoma in the External Auditory Canal Causing Ipsilateral Hearing Loss

Background: Salivary duct carcinoma (SDC) is a rare aggressive tumor. Most tumors are not confined to the salivary ducts; rather, they invade the major and minor salivary glands. Only a few case reports on such tumors in other primary sites have appeared. Case presentation: A 40-year-old male complained of right hearing loss (a common condition), but we made an extremely rare diagnosis of an SDC in the external auditory canal (EAC). EAC cancers are frequently misdiagnosed. In our patient, the otoscope revealed a smooth, bulging subcutaneous lesion with a non-epithelial defect suggestive of a benign lesion. However, an SDC of the EAC was confirmed through pathological and immunohistochemical analysis. Conclusions: We suggest detailed evaluation of even smooth EAC subcutaneous lesions to avoid erroneous diagnoses. To the best of our knowledge, this is the first report of SDC in the EAC.

Predictive and Prognostic Biomarker Identification in a Large Cohort of Androgen Receptor-Positive Salivary Duct Carcinoma Patients Scheduled for Combined Androgen Blockade

Patients suffering from recurrent or metastatic (R/M) salivary duct carcinoma (SDC) are often treated with combined androgen blockade (CAB). However, CAB frequently fails, resulting in a worse prognosis. Therefore, biomarkers that can predict treatment failure are urgently needed. mRNA from 76 R/M androgen receptor (AR)-positive SDC patients treated with leuprorelin acetate combined with bicalutamide was extracted from pre-treatment tumor specimens. AR, Notch, MAPK, TGFβ, estrogen receptor (ER), Hedgehog (HH), and PI3K signaling pathway activity scores (PAS) were determined based on the expression levels of target genes. Additionally, 5-alpha reductase type 1 (SRD5A1) expression was determined. These markers were related to clinical benefit (complete/partial response or stable disease ≥6 months) and progression-free and overall survival (PFS/OS). SRD5A1 expression had the highest general predictive value for clinical benefit and positive predictive value (PPV: 85.7%). AR PAS had the highest negative predictive value (NPV: 93.3%). The fitting of a multivariable model led to the identification of SRD5A1, TGFβ, and Notch PAS as the most predictive combination. High AR, high Notch, high ER, low HH PAS, and high SRD5A1 expression were also of prognostic importance regarding PFS and SRD5A1 expression levels for OS. AR, Notch PAS, and SRD5A1 expression have the potential to predict the clinical benefit of CAB treatment in SDC patients. SRD5A1 expression can identify patients that will and AR PAS patients that will not experience clinical benefit (85.7% and 93.3% for PPV and NPV, respectively). The predictive potential of SRD5A1 expression forms a rational basis for including SRD5A1-inhibitors in SDC patients' treatment.

HER2 Positivity in Histological Subtypes of Salivary Gland Carcinoma: A Systematic Review and Meta-Analysis

Background

HER2 aberrations in salivary gland carcinomas (SGC) as well as benefit of HER2 directed therapy have been reported in small studies. However, reliable estimates of the prevalence of HER2 positivity in SGC and its various histological subtypes are lacking.

Objective

To assess the prevalence of HER2 positivity in histological subtypes of salivary gland carcinomas (SGC).

Methods

Studies were identified by a systematic review of the literature. Data on in situ hybridization (ISH) and immunohistochemistry (IHC) were extracted to derive pooled prevalence estimates calculated by a random effects model. Characteristics of the studies were extracted for subgroup analysis.

Results

Fifty studies including 3372 patients were identified, providing data on sixteen histological subtypes. Based on the meta-analysis, the estimated prevalence of HER2 positivity were 43% (95% CI: 36% – 51%) in salivary duct carcinoma (SDC), 39% (95% CI: 32% – 45%) in carcinoma ex pleomorphic adenoma (CEP), 17% (95% CI: 7.5% – 33%) in squamous cell carcinoma (SCC), 13% (95% CI: 7.6% – 21%) in adenocarcinoma NOS (ADC), 6.7% (95% CI: 0.17%-32%) in poorly differentiated carcinoma, 5.5% (95% CI: 2.9% – 9.6%) in mucoepidermoid carcinoma, 4.3% (95% CI: 1.4% – 13%) in myoepithelial carcinoma, 1.8% (95% CI: 0.04%-9.6%) in epithelial-myoepithelial carcinoma, 0.45% (95% CI: 0.0097% – 18%) in acinic cell carcinoma and 0.15% (0.037% – 5.4%) in adenoid cystic carcinoma. Estimates for five additional subtypes were assessed.

Conclusion

Prevalence of HER 2 positivity in SGC varies greatly based on histological subtype, with SDC, CEP, SCC, and ADC displaying the highest rates.

Synchronous occurrence of IgG4-related sialadenitis and ductal carcinoma of the parotid gland: a case report

Immunoglobulin G4-related disease (IgG4-RD) is a rare chronic systemic inflammatory pathology that poses a diagnostic challenge since it can simulate malignancy when it affects a salivary gland as a mass-like lesion. Here, the authors report an unusual clinical case of a 42-year-old man who presented with a painless, slow-growing swelling located in the right parotid gland with a 12-month evolution. Based on imaging tests and open biopsy, a diagnosis of chronic parotitis was presumed and oral methylprednisolone was prescribed. Due to poor response to medication, a total parotidectomy preserving the facial nerve was performed. The final pathology described a unilateral IgG4-related sialadenitis (IgG4-RS) in the parotid gland in combination with a poorly differentiated multifocal ductal carcinoma. The postoperative course was uneventful except for a temporary facial paresis (grade III according to the House-Brackmann classification system) that resolved completely within 5 months. There were no systemic manifestations on the whole-body 18F-FDG PET/CT. Adjuvant radiotherapy was administered without complications. Twenty-four months follow-up after surgery showed no recurrence or evidence of systemic involvement. This clinical report highlights the importance of considering the synchronous occurrence of a carcinoma underlying an isolated parotid gland mass in the context of IgG4-RS, especially if there is no response to prior steroid medication.

Androgen Deprivation Therapy for Patients with Androgen-Receptor-Positive Metastatic Salivary Duct Carcinoma: A Case Report and Review of the Literature

Salivary duct carcinoma (SDC) is a rare and aggressive malignancy with high rates of recurrence and metastasis. There are no standard treatment options available for patients with recurrence and metastases. The case of a 61-year-old male with SDC of the left parotid gland is presented in this study. The results revealed that the patient’s tumour had strong positive staining for androgen receptor (AR) expression, mutations in HRAS and PIK3CA but not in other related genes, and no gene amplification of HER-2. After the primary therapy of parotidectomy with neck dissection and postoperative radiation, bone metastases were found in the ribs, pelvis and spine. Androgen deprivation therapy (ADT) involving combined androgen blockade (CAB) was effective as the first-line therapy for the patient’s metastases and resulted in a progression-free survival (PFS) of over 7 months to date. In conclusion, androgen deprivation therapy is recommended for patients with recurrent or metastatic SDC positive for androgen receptor expression.

Educational Case: Diagnostic Approach to Salivary Gland Neoplasms

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, seehttp://journals.sagepub.com/doi/10.1177/2374289517715040. ¹

Diagnostic discrepancy in second opinion reviews of primary epithelial neoplasms involving salivary gland: An 11-year experience from a tertiary referral center focusing on useful pathologic approaches and potential clinical impacts

AIMS

In the era of precision medicine, accurate pathologic diagnoses are crucial for appropriate management.

METHODS

We herein described the histologic features and clinical impacts of 66 salivary gland epithelial neoplasms in which the diagnosis was altered after expert review.

RESULTS

The most common revised diagnosis was that of salivary duct carcinoma (SDC, n = 12), adenoid cystic carcinoma (n = 12), and myoepithelial carcinoma (n = 10). The most common initial diagnosis was mucoepidermoid carcinoma (n = 19) with SDC being the most common revised diagnosis (7/19). Thirteen salivary gland carcinomas were initially diagnosed as benign entities, whereas five benign tumors were initially interpreted as carcinoma. The change in diagnosis was considered to be clinically significant in 65 (97%) cases.

CONCLUSIONS

Given their rarity, salivary gland neoplasms are prone to diagnostic inaccuracy and discrepancy. A constellation of histologic features and ancillary studies are useful in reaching the correct diagnosis, which can have significant clinical impacts.

Parotid Salivary Duct Carcinoma With a Prominent Squamous Component: Immunohistochemical Profile, Diagnostic Pitfalls, and Therapeutic Implications

Salivary duct carcinoma of the parotid gland is a highly aggressive epithelial malignancy morphologically resembling high-grade, invasive, and in situ breast carcinoma. It can occasionally present with variable morphology making it diagnostically challenging in cases with unusual morphological components. Ancillary testing, particularly androgen receptor (AR) positivity on immunohistochemistry, can be very helpful in cases that demonstrate extensive squamous morphology, since AR positivity is uncommon in both the primary salivary gland and metastatic squamous cell carcinomas to the parotid. In this report, we describe a case of salivary duct carcinoma that showed only a squamous cell carcinoma component on the initial primary tumor site biopsy, as well as in subsequent contralateral neck lymph node and skin metastases. Apart from the variable morphology, the typical salivary duct and squamous cell carcinoma tumor components also showed significant immunohistochemical differences, including differential staining of human epidermal growth factor receptor 2/neu. The associated diagnostic pitfalls, distinct immunoprofiles of the tumor components, helpful adjuncts for making the correct diagnosis, and associated therapeutic implications are discussed.

Enhanced Angiogenesis in Salivary Duct Carcinoma Ex-Pleomorphic Adenoma

Salivary duct carcinoma (SDC) is morphologically similar to breast cancer, with HER2-overexpression reported. With regard to the pattern of disease onset, SDC can arise from de novo or carcinoma ex-pleomorphic adenoma (Ca-ex-PA). Recently, multiple molecular profiles of SDC as well as breast cancer have been reported, with significant differences in HER2 expression between Ca-ex-PA and de novo. We assessed the differences in gene expression between onset classifications. We conducted immunohistochemical analysis and HER2-DISH for 23 patients and classified SDCs into three subtypes as follows: “HER2-positive” (HER2+/any AR), “Luminal-AR” (HER2-/AR+), and “Basal-like” (HER2-/AR-). We assessed the expression levels of 84 functional genes for 19 patients by using a qRT-PCR array. Ten cases were classified as HER2-positive, seven cases as Luminal-AR, and six cases as Basal-like. The gene expression pattern was generally consistent with the corresponding immunostaining classification. The expression levels of VEGFA, ERBB2(HER2), IGF1R, RB1, and XBP1 were higher, while those of SLIT2 and PTEN were lower in Ca-ex-PA than in de novo. The functions of those genes were concentrated in angiogenesis and AKT/PI3K signaling pathway (Fisher’s test: p-value = 0.025 and 0.004, respectively). Multiple machine learning methods, OPLS-DA, LASSO, and RandomForest, also show that VEGFA can be a candidate for the characteristic differences between Ca-ex-PA and de novo. In conclusion, the AKT/PI3K signaling pathway leading to angiogenesis was hyper-activated in all SDCs, particularly in those classified into the Ca-ex-PAs. VEGFA was over-expressed significantly in the Ca-ex-PA, which can be a crucial factor in the malignant conversion to SDC.

Solitary adrenal metastasis from salivary duct carcinoma of the parotid gland successfully treated by surgery: A case report

RATIONALE

Salivary duct carcinoma (SDC) is a rare and highly aggressive cancer with a poor prognosis. SDC demonstrates a potential for invasive growth with early regional and distant metastasis to organs, such as bone, lung, liver, and brain. Because, adrenal gland metastasis from SDC is rare, its treatment options are not well established. Herein, we report a case of SDC metastasis from the parotid gland to the adrenal gland, which was successfully treated by surgery.

PATIENT CONCERNS

The patient had an abnormal but painless lump on the right parotid gland. The size of the mass had increased over a period of 3 years. The patient underwent complete removal of the right parotid gland and radical neck dissection followed by adjuvant radiotherapy and chemotherapy. Two years later, a mass was identified in the left adrenal gland by computed tomography. As no local recurrence or metastasis to other organs was observed, the patient underwent adrenalectomy.

DIAGNOSES

Metastasis of SDC in the adrenal gland was confirmed by histopathological examination of the adrenalectomized specimen.

INTERVENTIONS

After adrenalectomy, the patient was followed-up without adjuvant therapy.

OUTCOMES

The patient was well and alive during the 13-month postoperative follow-up period without any complications.

LESSONS

Surgical resection of solitary metastatic lesion may show a survival benefit with metastatic SDC.

Efficacy of Pyrotinib in HER2-Overexpressing Salivary Duct Carcinoma With Lung Metastasis: A Case Report

Background: Salivary duct carcinoma (SDC), an aggressive and rare malignancy with poor prognosis, is mostly associated with the overexpression of the androgen receptor (AR) and human epidermal growth factor receptor 2 (HER2). However, limited data are available for the targeting of both HER2 and AR in advanced/metastatic SDC.

Case Presentation: A 62-year-old man with advanced SDC accompanied by lung and lymph node metastasis showed disease progression after two lines of chemotherapy and endocrine therapy. Metastatic lesions from the lung biopsy were obtained, and immunohistochemistry (IHC) indicated the overexpression of AR and HER2 (3+). The patient was administered pyrotinib (a pan-ErbB receptor tyrosine kinase inhibitor) and bicalutamide (an androgen receptor antagonist) as a third-line treatment. During the ten months of follow-up, a durable partial response was achieved with this combination.

Conclusions: This is the first clinical study to report the successful application of pyrotinib in a patient with advanced SDC. We recommend that pyrotinib and bicalutamide be used as salvage therapy for AR and HER2-positive advanced metastases in SDC, given the favorable response and clinical benefit.

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

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

Malignancies in Patients with IgG4-Related Diseases in Head and Neck Regions

Immunoglobulin G4-related disease (IgG4-RD) is a recently recognized disease, characterized by high serum IgG4 concentrations and IgG4-producing plasma cell expansion with fibrotic or sclerotic changes in affected organs. Recent work has focused on the relationship between IgG4-RD and malignancies, but there is no report of malignancies associated with IgG4-RD in head and neck regions. The aim of this study was to analyze the clinicopathological characteristics of malignancies in patients with IgG4-RD in head and neck regions. We retrospectively analyzed 26 patients with IgG4-RD (12 men and 14 women aged 60.6 ± 11.6 years). The mean follow-up period was 26.6 months (from 12 to 96 months). These patients were divided into single-lesion group (n = 12) with IgG4-RD only in head and neck regions and multiple-lesion group (n = 14) with IgG4-RD in other regions. There was no significant difference in serum IgG4 concentrations between the single-lesion group (459.4 ± 336.4 mg/dL) and the multiple-lesion group (908.0 ± 739.2 mg/dL) (P = 0.07), whereas the IgG4/IgG ratio was significantly lower in the single-lesion group (22.8 ± 11.0%; n = 11) compared with the multiple-lesion group (31.7 ± 15.0%; n = 11, P = 0.02). Among the 26 patients, two patients (7.7%), both in the multiple-lesion group, developed life-threatening malignancies (salivary duct carcinoma in the submandibular gland and lymphoma in the orbital tissue). All physicians need to keep in mind the possible coexistence of malignancies in patients with IgG4-RD with high IgG4/IgG ratio and multiple lesions at the time of diagnosis.

The molecular landscape and microenvironment of salivary duct carcinoma reveal new therapeutic opportunities

Purpose: Salivary duct carcinoma (SDC) is a rare and aggressive salivary gland cancer subtype with poor prognosis. The mutational landscape of SDC has already been the object of several studies, however little is known regarding the functional genomics and the tumor microenvironment despite their importance in oncology. Our investigation aimed at describing both the functional genomics of SDC and the SDC microenvironment, along with their clinical relevance.

Methods: RNA-sequencing (24 tumors), proteomics (17 tumors), immunohistochemistry (22 tumors), and multiplexed immunofluorescence (3 tumors) data were obtained from three different patient cohorts and analyzed by digital imaging and bioinformatics. Adjacent non-tumoral tissue from patients in two cohorts were used in transcriptomic and proteomic analyses.

Results: Transcriptomic and proteomic data revealed the importance of Notch, TGF-β, and interferon-γ signaling for all SDCs. We confirmed an overall strong desmoplastic reaction by measuring α-SMA abundance, the level of which was associated with recurrence-free survival (RFS). Two distinct immune phenotypes were observed: immune-poor SDCs (36%) and immune-infiltrated SDCs (64%). Advanced bioinformatics analysis of the transcriptomic data suggested 72 ligand-receptor interactions occurred in the microenvironment and correlated with the immune phenotype. Among these interactions, three immune checkpoints were validated by immunofluorescence, including CTLA-4/DC86 and TIM-3/galectin-9 interactions, previously unidentified in SDC. Immunofluorescence analysis also confirmed an important immunosuppressive role of macrophages and NK cells, also supported by the transcriptomic data.

Conclusions: Together our data significantly increase the understanding of SDC biology and open new perspectives for SDC tumor treatment. Before applying immunotherapy, patient stratification according to the immune infiltrate should be taken into account. Immune-infiltrated SDC could benefit from immune checkpoint-targeting therapy, with novel options such as anti-CTLA-4. Macrophages or NK cells could also be targeted. The dense stroma, i.e., fibroblasts or hyaluronic acid, may also be the focus for immune-poor SDC therapies, e.g. in combination with Notch or TGF-β inhibitors, or molecules targeting SDC mutations.

What do we know about the cytological features of pure intraductal carcinomas of the salivary glands?

OBJECTIVE

Intraductal carcinomas (IDCs) are rare, poorly characterised salivary gland tumours. The cytological features of IDCs are even less known. In this paper, a systematic literature review of pure IDCs (without stromal invasion, not associated with other histotypes) of low-grade (LG-IDCs) and high-grade (HG-IDCs) was performed.

METHODS

The bibliographic research included multiple databases (PubMed, Scopus, Web of Science). Mild-moderate nuclear atypia favoured LG-IDCs, severe atypia favoured HG-IDCs.

RESULTS

Preoperative fine-needle aspiration cytology (FNAC) was performed in 13/94 published cases (14%): 10 parotid; two oral; one submandibular. All the cases were histologically LG-IDCs, except two parotid IDCs. FNAC results included: negative for malignancy (three of 13 cases, 23%); tumour of uncertain malignant potential (seven of 13, 54%); malignancy (three of 13, 23%). The ductal component was identified in two cases; mucoepidermoid carcinoma was suggested in two additional cases. The grade was underestimated on FNAC evaluation in one HG-IDC as focal high-grade features were present on subsequent histological examination. The cases diagnosed as malignant tumours or describing intermediate atypia resulted in LG-IDCs on subsequent histology. Occasional mitoses were described only in one HG-IDC; this feature may have not been considered in the remaining published cases.

CONCLUSIONS

FNAC and clinico-pathological correlation are important aids for clinicians and pathologists. FNAC could assist surgery even if an accurate diagnosis is sometimes impossible. Discrepancy in grading the nuclear atypia between the FNAC material and the resected specimen can occur, sometimes being unavoidable. Further studies are needed to better characterise this rare tumour.

Intraductal carcinomas of the salivary glands: systematic review and classification of 93 published cases

Intraductal carcinomas (IDCs) are rare, not well-characterized salivary gland tumors. A systematic literature review of pure IDCs (without stromal invasion) of low-grade (LG-IDCs) or high-grade (HG-IDCs) was performed: IDCs were classified using the apocrine (AR+/S100-) vs intercalated (S100+/AR-) classification. Eighty-two LG-IDCs and 11 HG-IDCs were identified (84% parotid; 11% oral; 3% submandibular; 1% lacrimal; and 1% unknown). Out of 11 HG-IDCs, 2 HG-IDCs (18%) recurred as HG-IDC or invasive carcinoma. IDCs were classified as follows: intercalated (30%); mixed apocrine and intercalated (27%); apocrine (11%); oncocytic (6%); intercalated with focal oncocytic features (1%); and unclassifiable (25%). Double AR/S100 expressors (4%) or discrepancies between morphology and immunophenotype (9%) were found. Apocrine features and necrosis were more frequent in HG-IDCs (55%; 45%). Pleomorphism favored HG-IDCs (especially when combined with >10 mitoses/10 HPFs and/or Ki67 index >10%), being associated with apocrine areas at least in 3 HG-IDCs (27%). IDCs were typically mammaglobin+/ER-/PR-/DOG1-. No immunomarker clearly distinguished HG-IDCs from LG-IDCs. About 57% IDCs (16 LG-IDCs, 1 HG-IDC) showed RET rearrangements, including NCOA4-RET (eight intercalated and two unclassifiable IDCs) and TRIM27-RET fusions (two mixed IDCs). No ETV6, ALK-1, ROS, NTRK3, MAML2, MAML3, or PLAG1 rearrangements were identified. Complete excision and total sampling should exclude invasive areas.

Prediction of clinical benefit from androgen deprivation therapy in salivary duct carcinoma patients

Androgen deprivation therapy (ADT) is first‐line palliative treatment in androgen receptor‐positive (AR+) salivary duct carcinoma (SDC), and response rates are 17.6–50.0%. We investigated potential primary ADT resistance mechanisms for their predictive value of clinical benefit from ADT in a cohort of recurrent/metastatic SDC patients receiving palliative ADT (n = 30). We examined mRNA expression of androgen receptor (AR), AR splice variant‐7, intratumoral androgen synthesis enzyme‐encoding genes AKR1C3, CYP17A1, SRD5A1 and SRD5A2, AR protein expression, ERBB2 (HER2) gene amplification and DNA mutations in driver genes. Furthermore, functional AR pathway activity was determined using a previously reported Bayesian model which infers pathway activity from AR target gene expression levels. SRD5A1 expression levels and AR pathway activity scores were significantly higher in patients with clinical benefit from ADT compared to those without benefit. Survival analysis showed a trend toward a longer median progression‐free survival for patients with high SRD5A1 expression levels and high AR pathway activity scores. The AR pathway activity analysis, and not SRD5A1 expression, also showed a trend toward better disease‐free survival in an independent cohort of locally advanced SDC patients receiving adjuvant ADT (n = 14) after surgical tumor resection, and in most cases a neck dissection (13/14 patients) and postoperative radiotherapy (13/14 patients). In conclusion, we are the first to describe that AR pathway activity may predict clinical benefit from ADT in SDC patients, but validation in a prospective study is needed.

What's new?

Androgen deprivation therapy (ADT) is a leading treatment strategy in the palliative care of patients with androgen receptor (AR)‐positive salivary duct carcinoma (SDC). However, while as many as half of patients may respond to ADT, resistance frequently emerges, undermining its use. In this investigation of primary ADT resistance mechanisms, expression of the androgen synthesis enzyme‐encoding gene SRD5A1 and functional activity of the AR pathway were found to predict clinical benefit from ADT in SDC patients. High AR pathway activity scores were further linked to improved disease‐free survival in SDC patients with locally advanced disease who received adjuvant ADT.

Treatment of HER2+ metastatic salivary ductal carcinoma in a pregnant woman: a case report

Salivary duct carcinoma (SDC) is a rare and aggressive malignancy with a high mortality and poor response to treatment in the advanced setting. Human epidermal growth factor 2 (HER2) can be amplified in a fraction of SDC. We describe the case of HER2+ metastatic SDC of the submandibular gland in a young pregnant woman treated by multimodal treatment (chemotherapy, radiotherapy and targeted therapy). During pregnancy, a 27-year-old woman developed SDC of the left submandibular gland with lung and bone metastases. Given the HER2 overexpression, she was treated with trastuzumab, paclitaxel and cisplatin. Since the tumor had arisen during pregnancy, triptorelin was administered after delivery. A complete remission was observed, and after eight cycles of chemotherapy, radiotherapy was started in association with trastuzumab and triptorelin. A prolonged disease control and complete visceral remission were observed. Multimodal therapy based on patient’s tumor characteristics showed good clinical efficacy in the treatment of metastatic SDC.

The immune microenvironment and expression of PD-L1, PD-1, PRAME and MHC I in salivary duct carcinoma

AIMS

Salivary duct carcinoma (SDC) is an aggressive salivary malignancy that results in high mortality rates and is often resistant to chemotherapy. Anti-programmed death-1 (PD-1)/programmed death ligand-1 (PD-L1) checkpoint inhibitors have led to dramatic improvements in patients with various cancers. Other immunotherapeutic approaches, e.g. cancer vaccines, have shown promising results. Cancer testis antigens, e.g. preferentially expressed antigen in melanoma (PRAME), are regarded as promising vaccine targets because of their tumour-specific expression pattern.

METHODS AND RESULTS

We analysed the immunoexpression of PD-L1, PD-1, major histocompatibility complex class I (MHC I) and PRAME in 53 SDCs. The immunoexpression levels of PD-L1 in tumour cells (TCs) and immune cells (ICs), PD-1 in ICs, PRAME in TCs and MHC I in TCs were analysed, and were correlated with outcome. PRAME expression was seen in 83% of SDCs. No PRAME staining was present in normal salivary gland tissue. With the three established diagnostic algorithms proposed for head and neck squamous cell carcinoma, the criteria being a combined positive score of ≥1, TC% ≥1%, and TC% ≥25%, 35 (66%), 17 (32%) and three cases (6%), respectively, were deemed to be positive for PD-L1. PD-1-positive ICs were seen in 35 (66%) cases. MHC I down-regulation was seen in 82% of SDCs. There was a significant correlation among PD-L1 expression in ICs, PD-1 expression in ICs, and PRAME expression in TCs. PD-L1 expression in TCs and lack of PD-1 expression in ICs were associated with decreased disease-specific survival in SDC patients.

CONCLUSIONS

Alterations of the tumour immune microenvironment are common in SDCs, including expression of PD-1/PD-L1 and PRAME, which opens the way to potential novel immune therapies, such as cancer vaccination and PD-1/PD-L1 blockade, in these tumours.

A case of carcinoma ex pleomorphic adenoma arising from multinodular pleomorphic adenoma of the buccal region

In multinodular lesions or tumors with mixed benign and malignant components, malignant elements may be undetectable using fine-needle aspiration biopsy/cytology in preoperative pathological diagnosis of some cases, because of sampling error.

First Line Androgen Deprivation Therapy vs. Chemotherapy for Patients With Androgen Receptor Positive Recurrent or Metastatic Salivary Gland Carcinoma-A Retrospective Study

Objectives: There is a lack of effective therapy for recurrent or metastatic salivary gland carcinoma. Androgen deprivation therapy has demonstrated efficacy in cases of salivary duct carcinoma (SDC) and high-grade adenocarcinoma not otherwise specified (NOS) that express androgen receptor.

Materials and Methods: We conducted a single institution retrospective cohort study examining patients treated for recurrent/metastatic SDC or high-grade adenocarcinoma NOS of the salivary gland. Survival analyses were performed to assess for efficacy of first-line androgen deprivation therapy (ADT) vs. first-line conventional cytotoxic chemotherapy. Efficacy of salvage ADT was also assessed.

Results: Fifty-eight patients were reviewed. Thirty-five patients had recurrent/metastatic disease of which 28 had SDC (80%) and 7 had high-grade adenocarcinoma NOS (20%). Median overall survival for first-line ADT was 25 months compared to 25 months for first-line chemotherapy [RR 0.54 (0.23–1.28, p = 0.16)]. Patients treated with first-line ADT had a response rate of 45% (9/20) and patients treated with first-line chemotherapy had a response rate of 14% (2/14). Six patients received salvage ADT with 1 patient demonstrating complete response and 3 with stable disease as best response (clinical benefit rate 67%).

Conclusion: Overall survival for first line ADT and first line cytotoxic chemotherapy was comparable but response rates to first-line ADT were higher than those with first-line chemotherapy. Salvage ADT is active in recurrent/metastatic salivary gland carcinoma.

Carboplatin and Docetaxel in Patients With Salivary Gland Carcinoma: A Retrospective Study

BACKGROUND/AIM

The aim of this study was to evaluate the efficacy and safety of carboplatin/docetaxel combination therapy in patients with locally advanced and/or recurrent/metastatic (LA/RM) salivary gland carcinoma (SGC).

MATERIALS AND METHODS

This was a retrospective analysis of 24 patients that included six patients with AR-positive salivary duct carcinoma (SDC) after progressive disease treated with combined androgen blockade (CAB). Carboplatin (AUC5) and docetaxel (70 mg/m²) were administered for six courses every three weeks.

RESULTS

The overall response rate was 42%, the median progression-free survival was 8.4 months, and the median overall survival was 26.4 months. Among the six patients with CAB-resistant SDC, two achieved a partial response and two long-term stable disease. Grade 3/4 neutropenia and anemia were observed in 20-30% of the patients; all adverse events were manageable.

CONCLUSION

Carboplatin/docetaxel combination therapy may be a chemotherapeutic option for patients with LA/RM SGC, and a valuable second-line chemotherapy for CAB-resistant, AR-positive SDC.

Metastatic salivary duct carcinoma in cardiac and pleural effusions: A case report with immunocytochemical analysis for androgen receptor and HER2

Salivary duct carcinoma (SDC) is a relatively rare highly aggressive salivary gland tumor. Although SDC shows frequent lymph node and distant metastases, the presence of neoplastic cells in the pleural effusion is extremely rare. In this report, we describe the first documented cytological case of metastatic SDC in cardiac and pleural effusions with immunocytochemical analyses for androgen receptor (AR) and human epidermal growth factor receptor (HER)2. A 52-year-old Japanese male developed cardiac tamponade and respiratory discomfort after surgery and chemo-radiation therapy for SDC of the right submandibular gland. Aspiration of the cardiac and pleural effusions was performed. The Papanicolaou-stained cytological specimens of cardiac and pleural effusions showed that numerous small ball-like or papillary structures were present in an inflammatory background. The neoplastic cells had rich granular cytoplasm and large round to oval nuclei containing conspicuous nucleoli. Immunocytochemical analyses clearly demonstrated positivity for AR and strong membranous expression of HER2 in the neoplastic cells. Accordingly, a cytodiagnosis of metastatic SDC was made. Recently, HER2-targeted or AR deprivation therapy have been introduced for patients with SDC, therefore, determination of expression profiles of AR and HER2 may be crucial for developing a treatment strategy for patients with metastatic SDC. According to the results of the present report, immunocytochemical analyses for AR and HER2 in the effusion specimens may be useful for determination of a treatment strategy for patients with metastatic SDC.

Radiotherapy as salvage treatment of salivary duct carcinoma in major salivary glands without radical operations

Background

Salivary duct carcinoma (SDC) is an extremely rare and highly malignant carcinoma, and surgical radical resection is the most effective therapy. However, there were quite a proportion of patients receiving non-radical resections, and how to treat them remained controversial. Thus, the aim of this study is to evaluate whether postoperative radiotherapy could be a salvage treatment of SDC in major salivary glands without radical operations.

Patients and methods

We identified 40 pathologically diagnosed SDC patients who came to our hospital and did not receive radical operations. Thirty-three patients received at least one treatment (remedial operation, postoperative radiotherapy and chemotherapy), and seven patients only chose observation and received no further treatment. The prognostic indicators of the local-regional control (LRC) and distant disease-free survival were analyzed using the Kaplan-Meier methods and the Cox proportional hazards regression models.

Results

Thirteen patients experienced local-regional recurrence or local progression, and distant metastases were observed in 15 patients. Through multivariate analysis, we found that postoperative radiotherapy was associated with better LRC, but this kind of treatment did not show significant efficacy in the prevention of distant metastasis.

Conclusion

SDC is a rare, aggressive malignancy, and a substantial proportion of these patients experienced inadequate initial treatments. Although postoperative radiotherapy could not decrease distant metastases, it might help to improve LRC in patients with SDC.