Mammaglobin and DOG-1 expression in polymorphous low-grade adenocarcinoma: an appraisal of its origin and morphology

Studies on the association of malondialdehyde as a biomarker for oxidative stress and degree of malignancy in dogs with mammary adenocarcinomas

BACKGROUND

Mammary adenocarcinomas are one of the most common tumour diseases in bitches. The relationship between oxidative stress and the degree of malignancy of the tumour has not been sufficiently researched in veterinary medicine.

OBJECTIVES

The main objective was to investigate the potential role of MDA as a practice-relevant biomarker for the assessment of systemic oxidative stress and to determine whether this parameter can indicate the malignancy grade of a mammary adenocarcinoma.

METHODS

In the present pilot study, MDA plasma concentrations were analysed in 55 bitches with (n = 28) and without (n027) malignant adenocarcinomas of the mammary gland using two different measurement methods and the relationship to tumour size was investigated.

RESULTS

The mean MDA concentration measured by enzyme-linked immunosorbent assay (ELISA) was 289 ng/mL (range 365-634 ng/mL) in dogs with grade 1 adenocarcinoma (n = 13), 288.5 ng/mL (range 85-752 ng/mL) in dogs with grade 2 adenocarcinoma (n = 10), 332 ng/mL (range 239-947 ng/mL) in dogs with grade 3 (n = 5) adenocarcinoma and 293 ng/mL (range 175-549 ng/mL) in dogs without a mammary tumour (n = 27). When MDA was measured by HPLC, the average MDA concentration in the study group (n = 11) was 0.24 µmol/L (range 0.16-0.37) and that of the control group (n = 15) was 0.27 µmol/L (range 0.16-1.62). Thus, there were no significant differences between the study group with malignant adenocarcinomas and the control group in both examination methods (p > 0.05). Furthermore, there was no correlation between the MDA concentrations and the approximate volume of the mammary tumour.

CONCLUSION

The results highlight the challenges of providing a prognosis for the malignancy of a mammary adenocarcinoma based on MDA concentrations in plasma using ELISA or HPLC. As a result, histopathological examination remains the gold standard for diagnosing and differentiating adenocarcinomas of the mammary gland.

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.

Mammaglobin protein localization and gene expression in the salivary glands

PURPOSE

This study aims to delve deeper into the hypothesis that normal salivary gland tissue expresses both protein and mRNA of mammaglobin (MGB).

METHODS

Formalin-fixed paraffin-embedded samples of submandibular (10), parotid (5), palatal (5) and labial glands (30) salivary glands were immunohistochemically investigated. The labial samples were used to examine the MGB positive ratio (MGB-PR), and localize MGB by double immunofluorescence staining and quantitative mRNA gene expression. Mann-Whitney U and Kruskal Wallis rank-sum test for group comparison, and Spearman's rank correlation coefficient for correlation analysis were used.

RESULTS

The distribution of MGB-positive cells was variable throughout samples with significantly higher MGB-PR of acini than ducts (P = 0.00376), and there was no difference when compared based on age (P = 0.0646) and gender (P = 0.245). Besides acinar cells, a number of myoepithelial cells and ductal cells also demonstrated strong MGB reactivity with varying MGB mRNA expression levels in 6 of the 7 samples (with MGB-PR > 20%) tested.

CONCLUSION

This novel study shows that unlike aberrant protein expression in some carcinomas, MGB expression in salivary gland neoplasms represents the nature of original cells, giving a better insight into the neoplasms expressing MGB.

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.

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

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

Polymorphous adenocarcinoma of the salivary glands: reappraisal and update

Although relatively rare, polymorphous adenocarcinoma (PAC) is likely the second most common malignancy of the minor salivary glands (MiSG). The diagnosis is mainly based on an incisional biopsy. The optimal treatment comprises wide surgical excision, often with adjuvant radiotherapy. In general, PAC has a good prognosis. Previously, PAC was referred to as polymorphous low-grade adenocarcinoma (PLGA), but the new WHO classification of salivary gland tumours has also included under the PAC subheading, the so-called cribriform adenocarcinoma of minor salivary glands (CAMSG). This approach raised controversy, predominantly because of possible differences in clinical behaviour. For example, PLGA (PAC, classical variant) only rarely metastasizes, whereas CAMSG  often shows metastases to the neck lymph nodes. Given the controversy, this review reappraises the definition, epidemiology, clinical presentation, diagnostic work-up, genetics, treatment modalities, and prognosis of PAC of the salivary glands with a particular focus on contrasting differences with CAMSG.

Characterisation of DOG-1 Expression in Salivary Gland Tumours and Comparison with Myoepithelial Markers

DOG1 is an established diagnostic marker for gastrointestinal stromal tumours (GIST), but has been reported in salivary gland tumours (SGT) as an acinar and intercalated duct marker. However, its specificity and distribution is not well established. The aim of this study was to evaluate the diagnostic utility of DOG-1 expression in SGT in addition to comparing it with myoepithelial markers. Normal salivary tissue and SGT (n = 184) were examined for expression of DOG1 and a range of myoepithelial markers. SGT included: acinic cell carcinoma (ACC, n = 15), secretory carcinoma (SC, n = 9), pleomorphic adenoma (PA, n = 49), carcinoma ex-PA (Ca ex-PA, n = 11), adenoid cystic carcinoma (AdCC, n = 20), polymorphous adenocarcinoma (PAC, n = 6), myoepithelioma (n = 6), myoepithelial carcinoma (MC, n = 2), basal cell adenoma (BCA, n = 14), canalicular adenoma (CA, n = 19), mucoepidermoid carcinoma (MEC, n = 11), oncocytoma (n = 2), adenocarcinoma NOS (AdNOS, n = 4), basal cell adenocarcinoma (BCAC, n = 2), salivary duct carcinoma (SDC, n = 3) and papillary cystadenocarcinoma (PCAC, n = 1). Normal acini and ACC (14/15) showed strong luminal DOG1 staining; SC were largely negative with only focal expression in 3/9 cases. Luminal staining was seen in PA (14/49), PAC (4/6), Ca ex-PA (4/11) and AdCC (6/20). 8/11 MEC showed luminal and/or mucous cell staining. No staining was seen in myoepithelioma, MC, CA, adNOS and BCAC. BCA showed strong staining of myoepithelial cells in some cases (5/14). Variable myoepithelial DOG1 staining was seen in PA, Ca ex PA, BCA, SDC and PCAC which was not as consistent as myoepithelial markers such as calponin, p63 and αSMA. Absence of DOG1 can differentiate ACC from SC, but staining is variable in PA, PLGA and Ca ex-PA. Myoepithelial staining in some tumours but not in normal gland suggests a wider distribution in SGT than originally envisaged.