Cytopathologic Features of Secretory Carcinoma of Salivary Gland: Report of Two Cases

Salivary Gland Secretory Carcinoma; Review of 13 Years World-Wide Experience and Meta-Analysis

OBJECTIVES

Secretory Carcinoma is a malignant salivary gland tumor, initially described in 2010. This rare tumor is associated with the translocation t(12;15) (p13;q25), resulting in the fusion gene ETV6-NTRK3. Since this tumor is quite rare, most publications describe only small cohorts of patients. We aimed to investigate the clinical, pathological, and prognostic features of this newly defined malignant entity.

DATA SOURCES

Pubmed, Google Scholar, and Web of Science databases.

REVIEW METHODS

All published articles between 2010 and 2023 were reviewed. Search terms included the terms "Mammary Analogue Secretory Carcinoma" and "Secretory Carcinoma". All articles published in English reporting on Secretory Carcinoma of salivary glands were retrieved.

RESULTS

One-hundred and 12 retrospective articles reporting a total of 674 patients were included, with 52% males and a mean age of 44.9 ± 18.9. The event rate for patients with advanced-stage disease (Stage 3/4) at presentation was 24.1% (95% CI 17.6%-31.9%, I2  = 9.2%), 14.6% for regional metastases (95% CI 10.5%-20%, I2  = 12%), and the event rate of distant metastasis was 8.4% (95% CI 5.5%-12.7%, I2  = 4.2%). Adjuvant radiotherapy was administered for 30.3% of patients (95% CI 24.1%-37.2%, I2  = 21.5%). The recurrence rate was 19% (95% CI 15.1%-23.8%, I2  = 5%). Survival outcomes showed a 17.2% death of disease rate for Secretory Carcinoma patients (95% CI 13.5%-21.8%, I2  = 7.3%).

CONCLUSIONS

Secretory Carcinoma is a rare and relatively newly defined entity arising in the parotid gland most commonly. Characterized as a low-grade tumor, the majority of patients are diagnosed at an early stage, without regional or distant disease, and the prognosis is relatively good.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:1716-1724, 2024.

Prognostic factors in mammary analogue secretory carcinomas of the parotid gland: Systematic review and meta-analysis

Mammary analogue secretory carcinomas (MASCs) of the parotid gland are considered as low-grade malignancies with good clinical outcome but lacking data regarding prognostic factors. We performed meta-analysis assessing prognostic factors for disease-free survival (DFS) and overall survival (OS) in 256 patients with MASCs of the parotid gland. A total of 73 studies have met the inclusion criteria and 76.3% of patients were seen with T1 and T2 tumors and negative neck nodes. Lymph node metastasis (57.4%) and distant recurrences (46.2%) were particularly found in T4 tumors (p < 0.001). DFS at 5 and 10 years was 77.9% and 47.2% compared to 88.1% and 77.2% for OS at the same time points. Male sex, T3-T4 tumors, and recurrent disease represented independent worse prognosticators for survival outcome. Altogether, parotid gland MASCs show good long-term outcome, but T4 tumors behave significantly more aggressive and require extended treatment strategies along with close follow-ups.

A systematic review of secretory carcinoma of the salivary gland: where are we?

OBJECTIVE

The aim of this systematic review was to describe the epidemiology, diagnostic criteria, differential diagnosis, treatment, prognostic factors, and treatment outcomes of secretory carcinoma.

STUDY DESIGN

A comprehensive search of Lilacs, PubMed, Science Direct, and Web of Science databases was conducted to identify all case reports, letter to the editor, and histopathologic reclassifications regarding salivary gland secretory carcinoma published in English, Spanish, French, and Portuguese.

RESULTS

The final analysis included 119 studies, which totaled 642 secretory carcinoma diagnoses, with 239 case reports and 403 diagnostic reclassifications, mostly in the United States. The age range was 5 to 87 years, and cases were predominantly in males (58.7%) and mostly affecting the parotid glands (73.7%). The disease usually presents as a slow-growing, painless mass. The main differential diagnosis is acinic cell carcinoma, and the tumor is usually treated with surgery. The prognosis is considered favorable, although there have been reports of local recurrences, distant metastases, and deaths.

CONCLUSIONS

It is important that clinicians become aware of this salivary gland neoplasm and report clinical data, clinical course, management and long-term follow-up. There is an urgent need to conduct more clinical trials, especially on tropomyosin receptor kinase (TRK) inhibitors and other potential target therapy modalities.

An Underappreciated Cytomorphological Feature of Secretory Carcinoma of Salivary Gland on Fine Needle Aspiration Biopsy: Case Report with Literature Review

Secretory carcinoma (SC) of salivary gland, previously known as mammary analogue secretory carcinoma, is a rare low-grade malignancy harboring a diagnostic ETV6-NTRK3 gene fusion. SC of salivary gland shares histopathological, immunohistochemical and genetic characteristics with SC of the breast. There are several previous cytomorphological characterizations of SC of salivary gland reported in the literature. The most commonly reported patterns are of epithelial clusters with papillary architectural features, or of single dispersed epithelial cells on a background of abundant histiocytes. Tumor cells exhibit vacuolated eosinophilic cytoplasm and round to oval nuclei with regular nuclear contours and inconspicuous or small nucleoli. The cytomorphology of SC may closely mimic that of acinic cell carcinoma or low-grade mucoepidermoid carcinoma. Moreover, when cohesive epithelial clusters do not appear on the smears, it may be very difficult to distinguish dispersed tumor cells from histiocytes. In this article, we review the literature pertaining to SC cytomorphology and we report a fine needle aspiration biopsy case of SC in salivary gland showing well-defined intracytoplasmic hyaline globules, a feature that has not been previously reported. This novel cytomorphological feature may be helpful in distinguishing the tumor cells of SC from histiocytes and from other low-grade salivary gland tumors.

Mammary analogue secretory carcinoma of the minor salivary gland: report of two cases

Mammary analogue secretory carcinoma (MASC) is a recently described salivary gland tumour notable for a balanced chromosomal translocation t(12;15)(p13;q25) that contributes to ETV6 gene rearrangements. It was first reported in 2010 by Skalova et al. with histological features resembling secretory carcinoma of the breast and was acknowledged and referred to as "secretory carcinoma" in the updated 2017 WHO classification. It is reported that MASC accounts for <0.3% of all salivary gland tumours, with a finite number of published reports on it. MASC has a range of histological features and clinical behaviours. The histopathological diagnosis of MASC can be difficult with current immunohistochemical methods. One case was located in the left palate, and 1 case was located in the soft palate. The maximum diameter of the tumour was 1.4~3.7 cm. CT demonstrated a mass that had not invaded into the palate bone, and the patients underwent palate neoplasm expanded ectomy without neck dissection or postoperative radiation therapy. Histopathological examination revealed that the tumour cells consisted of a mixed arrangement of microcystic, papillary-cystic, follicular, and solid lobular growth patterns. Eosinophilic cytoplasm and intraluminal or intracytoplasmic colloid-like secretions were observed. The final pathology confirmed the diagnosis of MASC with immunohistochemically neoplastic cells staining positive for S-100 and mammaglobin. The patients were asymptomatic at their 12-month follow up. More studies are needed to identify the typical behaviour of this tumour and establish the standard treatment regimen. This study aims to reinforce the awareness of this tumour by analysing its clinicopathologic features, immunophenotype, and diagnosis.

Clinical characteristics of acinic cell carcinoma and secretory carcinoma of the parotid gland. Eur Arch Otorhinolaryngol. 2019;276:3461-3466. [PMID: 31440815 DOI: 10.1007/s00405-019-05604-4]

PURPOSE

Mammary analogue secretory carcinoma (SC) of the parotid gland is a relatively uncommon cancer associated with the ETV6-NTRK3 fusion product similar to breast cancer. The clinical characteristics and outcome of treatment were reviewed for patients with this tumor at our hospital.

METHODS

In this retrospective case series, 24 patients with a diagnosis of acinic cell carcinoma (AcCC) of the parotid gland were classified as having either SC or AcCC based on analysis of the ETV6-NTRK3 fusion gene. These two groups were compared with respect to their clinical and imaging characteristics (MRI/US), cytologic findings, accuracy of fine-needle aspiration cytology and frozen section, treatment outcomes, and immunohistochemical findings.

RESULTS

Based on re-classification by ETV6-NTRK3 fusion gene analysis, the diagnosis was SC in 14 patients and AcCC in 10 patients. The SC group had a significantly higher proportion of male patients and was also significantly younger than the AcCC group. Imaging studies revealed that SC was significantly more likely to show internal heterogeneity. Correct grading of both tumors was comparable by fine needle aspiration, with the rate being 60% for AcCC and 50% for SC. Diagnosis by frozen section biopsy diagnosis obtained the correct grade in 90% of the AcCC group and 93% of the SC group.

CONCLUSIONS

In 24 patients previously diagnosed with AcCC, re-analysis of the ETV6-NTRK3 fusion product indicated that 14 patients actually had SC. Although AcCC and SC show similarities of their biological aggressiveness and prognosis, patients with SC were significantly more likely to be male and younger.