Secretory Carcinoma of the Parotid: Making the Correct Diagnosis of a Rare Salivary Gland Carcinoma When Molecular Biology Testing Is Not Available

Secretory Carcinoma of the Parotid Gland Presenting as a Persistent Cystic Parotid Mass: A Case Report

Secretory carcinoma (SC) of the salivary glands, previously termed mammary analog secretory carcinoma (MASC), is a rare, low-grade malignant tumor of the salivary glands that closely resembles SC of the breast. This case report discusses parotid SC in a 40-year-old female patient who presented with recurrent parotid swelling. The report aims to demonstrate the importance of recognizing this rare tumor, raising awareness, and adding this case to world literature.

MASC Gets UNMASKED: Visiting a Rare Tumor with Emphasis on Cytomorphological Features

Background

Secretory carcinoma (SC) is a newly described entity which has been often misdiagnosed earlier as acinic cell carcinoma on cytology. Diagnosing SC was initially based upon identifying the ETV6:NTRK3 fusion gene with the help of fluorescence in situ hybridization (FISH). Lately, with more knowledge of the reliable histomorphology, cytology, and immunohistochemistry features, definitive diagnosis can be confidently made without the help of FISH in almost every case.

Materials and Methods

Six histologically confirmed cases of SC were studied. The cytology slides of all the six cases were retrieved and reviewed to identify the characteristic features which could have helped in raising the possibility of SC on fine needle aspiration cytology itself. Cell blocks were also studied, wherever available.

Results

Patients were all male with average age of 35.2 years. The six cases in the current study demonstrated at least focal cytoplasmic vacuolization of varying sizes, papillae formations, and bland nuclear features on fine needle aspirate smears. It was also seen that S-100 and mammaglobin immunohistochemistry (IHC) are very helpful in confirming the diagnosis.

Conclusions

The results of the current study highlight the cytomorphological features which may help in clinching the diagnosis SC on cytology itself. They also highlight certain cytological features which help to rule out the other differential diagnoses.

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.

Mammary Analogue Secretory Carcinoma of Submandibular Gland: A Case Report with Review of the Literature

Secretory carcinoma (SC) is a rare salivary gland tumor and has been recently included in the fourth edition of the World Health Organization classification of head and neck tumors. To understand the histopathologic findings and clinical behavior of mammary analogue secretory carcinoma (MASC) of the submandibular gland in a 23 year old female. MASC is an intriguing and rare malignant salivary gland tumor first described in 2010. It shares histologic, immunohistochemical and genetic features with secretory carcinoma of the breast. The clinical behavior of MASC ranges from slowly growing tumors to aggressive tumors that can cause widespread metastasis. Many cases of MASC were discovered in archived cases previously classified as pleomorphic adenoma, acinic cell carcinoma, mucoepidermoid carcinoma, and adenocarcinoma. They are only a few reported in submandibular gland. MASC is a newly recognized variant of salivary gland malignancy. Further research is needed to better delineate its overall prevalence and to define an appropriate treatment algorithm for this new clinical entity.

Clinicopathological investigation of secretory carcinoma cases including a successful treatment outcome using entrectinib for high-grade transformation: a case report

Background

Secretory carcinoma (SC) of the salivary gland is a recently described malignant tumor harboring characteristic ETV6-NTRK3 gene fusion. SC generally has a favorable clinical course, and is currently regarded as a low-grade carcinoma. However, a small subset of SCs demonstrates aggressive clinical features with histologically high-grade transformed morphology, the molecular pathogenesis of which has not yet been elucidated. In this study, we performed a clinicopathological and molecular genetic study of patients with SC of the head and neck displaying various clinical characteristics to investigate the differences of pathological and molecular genetics between low-grade and high-grade components of SC.

Case presentation

Three cases with SC of the head and neck, including a conventional low-grade SC and two high-grade transformed SCs are described. High-grade transformed SCs with histological features such as nuclear polymorphism, distinctive nucleoli and increased mitotic activity developed locoregional recurrence and distant metastasis. Immunohistochemical analysis revealed that low- and high-grade components showed different expression patterns for S-100 protein and mammaglobin, whereas all examined components were positive for p-STAT5. p53-positive cell population was markedly higher in one case with high-grade transformed SC. The proliferative activity of high-grade components was markedly increased, with the Ki-67 labeling index ranging up to 30–32%. A fluorescence in situ hybridization study with an ETV6 (12p13) break apart probe revealed split signals in the nuclei in all 3 cases. A targeted next-generation sequencing-based fusion assay demonstrated that all 6 clinical samples from the 3 patients showed the presence of the ETV6-NTRK3 fusion transcripts. One patient with high-grade transformed SC showed a dramatic clinical response to the pan-TRK inhibitor, entrectinib, for the treatment of locoregional recurrence and pulmonary metastasis.

Conclusions

High-grade transformed SC showed aggressive clinical and pathological features with increased Ki-67 labeling index. Molecular genetic study of gene rearrangement appears to be beneficial treatment as the presence of ETV6-NTRK3 translocation may represent a therapeutic target in SC, particularly the high-grade transformed type.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01155-6.

A case of "ETV6-FISH-negative" secretory carcinoma of the parotid gland: immunohistochemical study

Secretory carcinoma of the salivary glands is a relatively new disease concept, and is characterized by "morphological resemblance to mammary secretory carcinoma and ETV6-NTRK3 gene fusion." Herein we describe a confusing case and briefly discuss practical diagnostic problems. The patient was a 71-year-old Japanese man who had a tumor consistent with secretory carcinoma at the microscopic and immunohistochemical levels. Immunohistochemically, EMA and S100 protein were noted to be positive along with various cytokeratins as well as mammaglobin and pSTAT5. Moreover, vimentin was focally positive. Smooth muscle actin, p63, p40, and androgen receptor were negative. However, a search using fluorescence in situ hybridization did not reveal a definite split signal for the ETV6 gene. It is presumed that confirming the diagnosis of secretory carcinoma without genetic retrieval will be accepted as a diagnostic method, and we hope that worldwide general recognition may earlier reach "gradual acceptance."

Primary acinic cell carcinoma of mandible, report of a case and literature review

Introduction and importance

Acinic cell carcinoma (ACC) is a rare low-grade salivary gland malignancy that accounts for approximately 17% of all salivary gland malignancies. The most common site affected by ACC is the parotid gland followed by the submandibular glands, minor salivary glands, and sublingual glands. Also, it could hardly be observed in unusual sites such as the jaw bones.

Case presentation

This case is an example of a central acinic cell carcinoma in a 73-year-old man who came up with a painless gradual swelling for 15 months. Based on clinico-radio-pathologic findings, the diagnosis of a solid variant Intraosseous Acinic Cell Carcinoma was established. Subsequently, the patient underwent hemimandibulectomy and modified radical neck dissection, followed by postoperative radiotherapy. Within a six-month follow-up period, no evidence of residual tumor was found.

Clinical discussion

Central salivary gland carcinoma is a rare entity and intraosseous ACC is more scarcely observed. Based on our findings, a total of 17 cases of primary intraosseous ACC have been reported so far. Etiology and clinical presentations of this tumor are still vague due to its rarity.

Conclusion

Dentists and oral surgeons must be aware of such a rare malignant lesion when encountering a radiolucent lesion within the jaws. The early diagnosis and a complete surgical excision to achieve tumor-free surgical margins and a long-term follow-up could result in significantly improved survival rates.

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ACCs are a type of uncommon salivary gland tumors and the intra-osseous counterparts are extremely rare.

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Due to clinical and radiologic similarities to benign tumors, histopathologic and IHC findings should also be considered.

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Primary surgical design should be wide enough and en bloc resection should be suggested.

Secretory carcinoma of the breast limited to the dermis: Cutaneous or breast primary?

We offer a case of a 22-year-old woman who presented with a painless breast mass. Physical examination of the breast was unrevealing other than a palpable mass in close proximity to the nipple areolar region. No lymphadenopathy was noticed in the axilla or supraclavicular region. Sonographic assessment was performed and the findings were classified as Breast Imaging Reporting and Data System category 4. Because of the proximity of the mass to the skin surface, an excisional biopsy was performed. Final pathology disclosed a 5-mm invasive carcinoma. On pathologic examination, histopathologic and immunophenotypes supported the diagnosis of secretory carcinoma; however, whether the origin was from the breast parenchyma or skin tissue was not clearly discernable. Therefore, the patient was scheduled for sentinel lymph node biopsy with plans for axillary dissection if positive. While the overall prognosis for secretory carcinoma is good, with a low chance of metastasis, any ambiguity in breast mass diagnosis should be discussed in a multidisciplinary tumor board and should be treated aggressively particularly in younger patients.

Secretory Carcinoma of the Oral Cavity: A Retrospective Case Series with Review of Literature

Secretory carcinoma (SC) is an uncommon salivary gland neoplasm of the oral cavity that microscopically may mimic acinic cell carcinoma (ACC) and mucoepidermoid carcinoma (MEC). This study describes a series of SC in minor glands with a literature review. We performed a retrospective search for oral SC, within the archives of the University of Florida, Oral Pathology and Surgical Pathology Biopsy services from 2010 to 2018. A total of 10 SCs were identified in the oral and maxillofacial region, four of which were in the minor salivary glands. The demographic, clinical, histological, and molecular findings were aggregated for all 4 cases. Patient age varied from 30 to 60 years, with an average of 45 years. Two cases each were in female and male patients. Two cases presented on the labial mucosa, and one each on the hard and soft palate. Immunohistochemical (IHC) staining showed mammaglobin positivity in all cases, GATA3 positivity in two cases, S100 positivity in three cases, and SOX10 positivity in only one case. Fluorescence in situ hybridization demonstrated positivity for ETV6-NTRK3 fusion in 4 cases. Although oral SC is rare, pathologists should be aware of the histologic overlap between the SC and other salivary gland neoplasms such as ACC and MEC. A judicious application of IHC staining would aid in diagnosis. SC should be considered in the differential diagnosis for intraoral salivary gland tumors.

MUC4 is a valuable marker for distinguishing secretory carcinoma of the salivary glands from its mimics

AIMS

Secretory carcinoma (SC) (synonym: mammary analogue secretory carcinoma) is a low-grade salivary gland tumour that occurs in both major and minor salivary glands. SC is known for its wide morphological, architectural and immunohistochemical spectrum, which overlaps with those of several salivary gland neoplasms, including acinic cell carcinoma (AciCC) and intercalated duct-type intraductal carcinoma (IDC) in major salivary glands, and polymorphous adenocarcinoma (PAC) in minor salivary glands. These tumours share with SC some morphological features and SOX10 immunoreactivity; also, with the exception of AciCC, they all coexpress S100 and mammaglobin.

METHODS AND RESULTS

We compared MUC4 and mammaglobin expression in 125 salivary gland carcinomas (54 genetically confirmed SCs, 20 AciCCs, 21 PACs, and 30 IDCs) to evaluate the potential of these two markers to differentiate these entities. Moderate to strong diffuse MUC4 positivity was detected in 49 SCs (90.7%), as compared with none of the IDCs and PACs. In contrast, mammaglobin was frequently expressed in SCs (30 of 36 cases; 83.3%), IDCs (24/28; 85.7%), and PACs (7/19; 36.8%). Two of three high-grade SCs lost MUC4 expression in the high-grade tumour component. No significant correlation was found between MUC4 expression and the fusion variant in SC (ETV6-NTRK versus non-ETV6-NTRK).

CONCLUSION

The results of our study identify MUC4 as a sensitive (90.7%) and specific (100%) marker for SC, with high positive (100%) and negative (93.4%) predictive values. Thus, MUC4 may be used as a surrogate for SC in limited biopsy material and in cases with equivocal morphology.

Salivary Gland Carcinoma: Novel Targets to Overcome Treatment Resistance in Advanced Disease

Salivary gland carcinomas (SGCs) account for <5% of head and neck malignant neoplasms, further subcategorized in over 20 histological subtypes. For the most part, treatment for advanced disease is guided by morphology. SGCs in general respond poorly to a wide array of standard chemotherapy, with short durability, and significant toxicity. More recently, next-generation sequencing provided significant input on the molecular characterization of each SGC subtype, not only improving diagnostic differentiation between morphologically similar tumor types but also identifying novel driver pathways that determine tumor biology and may be amenable to targeted therapy. Among the most common histological subtype is adenoid cystic carcinoma, which often harbors a chromosome translocation resulting in an MYB-NFIB oncogene, with various degrees of Myb surface expression. In a smaller subset, NOTCH1 mutations occur, conferring a more aggressive pattern and potential sensitivity to Notch inhibitors. Salivary duct carcinomas may overexpress Her-2 and androgen receptors, with promising clinical outcomes after exposure to targeted therapies approved for other indications. Secretory carcinoma, previously known as mammary analog secretory carcinoma, is distinguished by an ETV6-NTRK3 fusion that can both help differentiate it from its morphologically similar acinar cell carcinoma and make it susceptible to Trk inhibitors. In the present article, we discuss the molecular abnormalities, their impact on tumor biology, and therapeutic opportunities for the most common SGC subtypes and review published and ongoing clinical trials and future perspectives for this rare disease.

Usefulness of immunohistochemistry to distinguish between secretory carcinoma and acinic cell carcinoma in the salivary gland

Secretory carcinoma (SC) of the salivary gland is a relatively newly described disease, separate from acinic cell carcinoma (ACC), which frequently displays ETV6-NTRK3 gene fusion. However, the differences between SC and ACC remain unclear. Here, histological reevaluation of 12 formerly diagnosed ACC cases was performed, which yielded a new diagnosis of SC in four cases due to a lack of obvious acinar-like cells. Immunohistochemically, phosphorylated signal transducer and activator of transcription 5 (p-STAT5) was expressed in SC but not in ACC, whereas discovered on GIST-1 (DOG1) was expressed in ACC but not in SC. Molecular analysis was possible in three SC cases, of which two showed the ETV6-NTRK3 fusion transcript on reverse-transcription polymerase chain reaction, as well as breaks in the ETV6 gene on fluorescence in situ hybridization. However, the remaining SC cases did not show this fusion transcript. Recently, several reports have suggested that SC might not be adequately diagnosed if the focus is placed solely on the ETV6-NTRK3 fusion gene due to genetic diversity. In this regard, immunohistochemistry of p-STAT5 and DOG1 is expected to be a useful alternative diagnostic tool to discriminate SC from ACC.