Immunohistochemical evaluation of androgen receptor, HER-2/neu, and p53 in benign pleomorphic adenomas

Estrogen Receptor, Progesterone Receptor, and HER-2 Expression in Recurrent Pleomorphic Adenoma

Pleomorphic adenoma (PA) is the most common salivary gland neoplasm and, although mostly benign, recurrences, being called recurrent pleomorphic adenoma (RPA) and malignant transformation to carcinoma ex pleomorphic adenoma (CXPA), do occur. Recently, attention has been focused on molecular targeted cancer therapy in various tumors, including salivary gland tumors. The aim of this study was to investigate the role of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER-2) in PA, RPA, and CXPA. In total, 20 cases of PA, 18 of RPA, and 7 cases of CXPA were immunohistochemically studied for ER, PR, and HER-2. For evaluation of ER and PR, only nuclear expression and greater than 10% positive cells were regarded as cutoff criteria. HER-2 was evaluated semiquantitatively and graded from 0 to 3+. HER-2 amplification was assessed by chromogenic in situ hybridization (CISH). Tumors were negative for ER, PR, and HER-2 in all cases of PA and RPA. A case of CXPA showed moderate and complete membranous staining, and 6 cases were negative. HER-2 amplification was not observed in any case. In conclusion, the lack of ER, PR, and HER-2 expression in PA, RPA, and CXPA suggests that these proteins are not involved in progression, recurrence, or malignant transformation of PA.

BRCA1/2 Mutations in Salivary Pleomorphic Adenoma and Carcinoma-ex-Pleomorphic Adenoma

Objectives:

It is hypothesized that carcinoma-ex-pleomorphic adenoma (Ca-ex-PA) is malignant from the beginning or is a malignant transformation of a recurrent or a long-standing pleomorphic adenoma (PA). The accumulation of genetic instabilities is suggested to be the main reason for malignant transformation in PA. The aim of this study was to determine the prevalence of BRCA1/2 mutations in PA and Ca-ex-PA.

Materials and Methods:

A total of ninety salivary gland tumors (45 Ca ex-PA and 45 PA) were selected. Immunohistochemistry was performed for all samples. Analyses were conducted through SPSS software version 22.0 (SPSS, Inc., Chicago, IL, USA). Chi-square test was used to examine the differences between the variables. Significant level was set at 0.05.

Results:

In general, 93.3% of PA samples showed positive staining for BRCA1 (in myoepithelial cells); however, BRCA2 positivity was found in 60% of samples (in myoepithelial cells). Among 45 samples of Ca-ex-PA, 93.3% of showed positivity for BRCA1 and 80% of samples showed positivity for BRCA2. Chi-square test found differences between PAs and Ca-ex-PAs regarding BRCA1/2 mutations in ductal cells and myoepithelial cells (P = 0.007, 0.000), respectively.

Conclusions:

The present study found a trend toward the presence of BRCA1/2 mutations in PA and Ca-ex-PA samples. Patients with BRCA1/2 mutation carriers are excellent cases for therapies, such as the poly (ADP) ribose polymerase inhibitor.

Expression of Hormone Receptors and HER-2 in Benign and Malignant Salivary Gland Tumors

With the advent of targeted therapies, expression of sex hormone receptors and HER-2 in salivary gland tumors (SGTs) is of clinical interest. Previous reports of estrogen (ER) and progesterone (PR) receptor expression have varied. Androgen receptor (AR) and HER-2 overexpression are frequently reported in salivary duct carcinoma (SDC), but have not been studied systematically in other SGTs. This study examines ER, PR, AR, and HER-2 expression in SGTs. Immunohistochemistry for ER, PR, AR, and HER-2 was performed on 254 SGTs (134 malignant). ER, PR, and AR expression was scored using Allred system. HER-2 expression was scored using Dako HercepTest guidelines. FISH for HER-2 amplification was performed on select cases with HER-2 overexpression (2-3+). No SGT demonstrated strong expression of ER or PR. Combined strong AR and HER-2 expression was seen in 22 carcinomas: 14/25 SDC, 3/16 poorly differentiated, two oncocytic, and one each carcinoma ex pleomorphic adenoma, squamous cell, and intraductal carcinoma. Eighteen additional high grade carcinomas had HER-2 overexpression with absent, weak, or moderate AR expression; eight high grade carcinomas had isolated strong AR expression with 0-1+ HER-2 staining. Of 15 tested cases, six demonstrated HER-2 amplification by FISH, all of which had 3+ immunoreactivity. Neither benign nor malignant SGTs had strong expression of ER or PR. None of the benign SGTs overexpressed AR or HER-2. Coexpression of AR and HER-2 should not define SDC, but immunostaining should be considered in high grade salivary carcinomas, as some show overexpression and may benefit from targeted therapy.

Histological, immunohistological and molecular characteristics of intraductal precursor of carcinoma ex pleomorphic adenoma support a multistep carcinogenic process

In recent years, multistep carcinogenesis of carcinoma ex pleomorphic adenoma (CEPA) has been identified, starting with intraductal neoplasia within pre-existent pleomorphic adenoma (PA). However, as yet there is no consensus regarding clinical relevance and appropriate terminology of precursor lesions in CEPA. We therefore decided to investigate precursor lesions, especially intraductal carcinoma, in a series of 85 cases of CEPA. Intraductal carcinoma confined by benign myoepithelial cells was found in 60 cases and mostly exhibited high-grade cellular atypia, increased cellular proliferation and frequent genetic alterations (TP53, Her2-neu, androgen receptor). Intraductal carcinoma was absent only in the myoepithelial type of CEPA. In 26 cases, purely intraductal CEPA with extensive intraductal expansion was found. This suggests that there is a long period of intraductal growth before extraductal intracapsular infiltration of the PA. We identified two different histomorphological types of intraductal carcinoma, which we call 'clinging' and 'solid' types. In summary, combined histological, immunohistological and molecular data strongly support multistep carcinogenesis starting with intraductal carcinoma for all non-myoepithelial types of CEPA. The clinical significance of our finding of two histomorphological types of intraductal carcinoma (clinging and solid) is not yet clear. Intraductal carcinoma, intracapsular invasive CEPA and minor extracapsular invasive CEPA (up to about 6 mm) all show favourable prognosis and together comprise half of the cases in our study.

Cytology of the Salivary Glands

Common usage of fine-needle aspirate (FNA) for salivary gland lesions is the preoperative determination of whether a lesion is neoplastic, its lineage, and if neoplastic, whether it is low grade/benign, or high grade. Immunohistochemical stains can be performed on cell blocks to determine lineage and help refine diagnosis, although their performance is not always equivalent to that seen in surgical specimens. Several characteristic translocations have been described in various entities in these categories, and these can be evaluated using fluorescence in situ hybridization. In the future, high-throughput next-generation sequencing panels may further refine cytologic diagnosis in salivary tumors.

p53 expression in pleomorphic adenoma of salivary glands: A systematic review and meta-analysis

OBJECTIVE

There are conflicting data regarding immunohistochemical expression of p53 in pleomorphic adenoma. This systematic review and meta-analysis aimed to examine whether p53 expression has a role in the pathogenesis of pleomorphic adenoma.

DESIGN

A comprehensive literature search for relevant studies published from 2000 up to end of 2014 was performed using PubMed, EMBASE and the Cochrane Library Databases. Only articles in which p53 detected by immunohistochemical staining were included. The meta-analysis was done using Comprehensive Meta-Analysis software.

RESULTS

Eighteen eligible studies were included in this meta-analysis. Heterogeneity measures showed a statistically significant Cochrane Q value (P-value<0.001). The random effects model showed an effect size of 0.254 with a 95% CI (0.139-0.417). The overall p53 positivity is 25.4%.

CONCLUSION

Mutant p53 has to be detected by more precise techniques to emphasize on its role in development of pleomorphic adenoma of salivary gland.

A novel cell line derived from pleomorphic adenoma expresses MMP2, MMP9, TIMP1, TIMP2, and shows numeric chromosomal anomalies

Pleomorphic adenoma is the most common salivary gland neoplasm, and it can be locally invasive, despite its slow growth. This study aimed to establish a novel cell line (AP-1) derived from a human pleomorphic adenoma sample to better understand local invasiveness of this tumor. AP-1 cell line was characterized by cell growth analysis, expression of epithelial and myoepithelial markers by immunofluorescence, electron microscopy, 3D cell culture assays, cytogenetic features and transcriptomic study. Expression of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) was also analyzed by immunofluorescence and zymography. Furthermore, epithelial and myoepithelial markers, MMPs and TIMPs were studied in the tumor that originated the cell line. AP-1 cells showed neoplastic epithelial and myoepithelial markers, such as cytokeratins, vimentin, S100 protein and smooth-muscle actin. These molecules were also found in vivo, in the tumor that originated the cell line. MMPs and TIMPs were observed in vivo and in AP-1 cells. Growth curve showed that AP-1 exhibited a doubling time of 3.342 days. AP-1 cells grown inside Matrigel recapitulated tumor architecture. Different numerical and structural chromosomal anomalies were visualized in cytogenetic analysis. Transcriptomic analysis addressed expression of 7 target genes (VIM, TIMP2, MMP2, MMP9, TIMP1, ACTA2 e PLAG1). Results were compared to transcriptomic profile of non-neoplastic salivary gland cells (HSG). Only MMP9 was not expressed in both libraries, and VIM was expressed solely in AP-1 library. The major difference regarding gene expression level between AP-1 and HSG samples occurred for MMP2. This gene was 184 times more expressed in AP-1 cells. Our findings suggest that AP-1 cell line could be a useful model for further studies on pleomorphic adenoma biology.

Massive transcranial parotid pleomorphic adenoma: recurrence after 30 years

Pleomorphic adenoma, also known as benign mixed tumor, is the most common tumor affecting the parotid gland and can reach massive size; however, intracranial invasion is rare. Recurrence of pleomorphic adenoma after excision is a well-known phenomenon and can present decades after resection of the primary tumor. Here we present the case of a 53-year-old man who presented to our clinic with ear fullness, otalgia, and hearing loss 30 years after undergoing total parotidectomy and external beam radiotherapy for pleomorphic adenoma. Magnetic resonance imaging revealed a massive transcranial tumor invading the mastoid cavity, the dura of the posterior fossa, the fallopian and semicircular canals, the jugular foramen, the lateral infratemporal fossa skull base, the sigmoid and transverse sinuses, and the superior parapharyngeal region. Gross examination and histopathological studies confirmed that the mass was a recurrent pleomorphic adenoma. Here we discuss the features of recurrent pleomorphic adenoma and review the current literature.

Carcinoma ex pleomorphic adenoma, with particular emphasis on early lesions

Carcinoma ex pleomorphic adenoma (CXPA) is a broad category of carcinomas of the salivary glands which includes at least 2 clinically relevant categories; one is referred here as early CXPA (ECXPA), the other as widely invasive CXPA. The former includes several histological patterns ranging from non-invasive/in situ/intraductal/intratubular, early invasive/extratubular/intracapsular and extracapsular (up to 6 mm). The latter includes any CXPA with invasion of >6 mm. The clinical behaviour of ECXPA is not aggressive and tends to overlap that of a pleomorphic adenoma (PA) which makes the histological report of carcinoma contradictory. These early malignant changes in PA are known since the 1970s but it has been the use of immunohistochemical and molecular genetic analysis for HER-2 and TP53 gene in the last decade that has clarified the genuine malignant nature of the cells. HER-2 and TP53 gene and protein are involved in the early stages of malignant transformation of PA. Moreover the immunohistochemical over-expression HER-2, p53 protein and Mib-1 proliferation marker may be useful markers to identify malignant areas in PA.

Takahashi R, Nagai T, Yoshida M, Suzuki F, Obikane H, Yamashina M, Matsubayashi J. Immunohistochemical analysis of salivary gland tumors: application for surgical pathology practice

Salivary gland tumors are relatively uncommon and there exists a considerable diagnostic difficulty owing to their diverse histological features in individual lesions and the presence of a number of types and variants, in addition to overlapping histological patterns similar to those observed in different tumor entities. The classification is complex, but is closely relevant to the prognostic and therapeutic aspects. Although hematoxylin-eosin staining is still the gold standard method used for the diagnosis, immunohistochemistry (IHC) can enhance the accuracy and be a helpful tool when in cases to investigate the subjects that cannot be assessed by histological examination, such as the cell nature and differentiation status, cell proliferation, and tumor protein expression. This review depicts on the practical diagnostic utility of IHC in salivary gland tumor pathology under the following issues: assessment of cell differentiation, focusing on neoplastic myoepithelial cells; discrimination of histologically mimic tumor groups; diagnosis of specific tumor types, e.g., pleomorphic adenoma, adenoid cystic carcinoma, and salivary duct carcinoma; and evaluation of malignancy and prognostic factors. IHC plays a limited, even though important, role in the diagnosis of salivary gland tumors, but is often useful to support the histological assessment. However, unfortunately few tumor type-specific markers are still currently available. For these reasons, IHC should be considered a method that can be used to assist the final diagnosis, and its results themselves do not directly indicate a definitive diagnosis.

Common Malignant Salivary Gland Epithelial Tumors

Malignant salivary gland epithelial tumors are histologically diverse with at least 24 recognized distinct entities. In general, malignant tumors account for 15% to 30% of parotid tumors, 40% to 45% of submandibular tumors, 70% to 90% of sublingual tumors, and 50% of minor salivary tumors. Common malignancies include mucoepidermoid carcinoma, adenoid cystic carcinoma, acinic cell carcinoma, salivary duct carcinoma, carcinoma ex pleomorphic adenoma, polymorphous lowgrade adenocarcinoma, and myoepithelial carcinoma. Each tumor type has its own unique histologic variants and prognostic pathologic features, and only mucoepidermoid carcinomas have a formalized grading system. The molecular pathogenesis of certain tumors, such as mucoepidermoid carcinoma and adenoid cystic carcinoma, has recently begun to be elucidated.

Rare Malignant and Benign Salivary Gland Epithelial Tumors

Although at least 24 distinct histologic salivary gland carcinomas exist, many of them are rare, comprising only 1% to 2% of all salivary gland tumors. These include epithelial-myoepithelial carcinoma, (hyalinizing) clear cell carcinoma, basal cell adenocarcinoma, cystadenocarcinoma, low-grade salivary duct carcinoma (low-grade cribriform cystadenocarcinoma), oncocytic carcinoma, and adenocarcinoma not otherwise specified. Few tumors (clear cell carcinoma and basal cell adenocarcinoma) have unique molecular correlates. Benign tumors, although histologically less diverse, are far more common, with pleomorphic adenoma and Warthin tumor the most common salivary gland tumors. Many benign tumors have malignant counterparts for which histologic distinction can pose diagnostic challenge.

Carcinoma ex pleomorphic adenoma of the salivary glands: distinct clinicopathologic features and immunoprofiles between subgroups according to cellular differentiation

In carcinoma ex pleomorphic adenoma (CXPA), pleomorphic adenoma (PA) and diverse carcinoma components showing luminal (ductal) or non-luminal (myoepithelial) differentiation coexist. To elucidate the clinicopathological implications of cellular differentiation in CXPA and the potential role of p53, vascular endothelial growth factor (VEGF), c-erbB-2, c-kit, and glucose transporter 1 (Glut-1) in carcinogenesis, we analyzed 11 CXPAs with luminal differentiation (CXPAs-LD) and 6 CXPAs with non-luminal differentiation (CXPAs-NLD) and compared protein expressions in residual PAs and carcinomas by immunohistochemistry. Among the CXPAs-LD, 5 were invasive and 8 were histologically high-grade tumors. The 5-year survival rate was 72.7%. P53, c-erbB-2, VEGF, and Glut-1 were more immunoreactive in carcinoma components than in PAs (P = 0.008, 0.004, 0.002, and 0.024, respectively); c-erbB-2 overexpression was associated with high histological grade (P = 0.024). Carcinoma components frequently lacked c-kit expression (P = 0.009). CXPAs-NLD were all low-grade and invasive with a larger mean tumor size (5.2 cm) than CXPAs-LD (3.3 cm) (P = 0.040). The patients remained disease-free without significant immunohistochemical expression. The immunoprofiles and clinical course of CXPA differed according to cellular differentiation. Therefore, it is important to report the histological subtype and to assess potential biomarkers in diagnostic and therapeutic trials.

Update on selected salivary gland neoplasms

CONTEXT

Malignancies of the salivary gland are uncommon and account for 0.3% of all malignancies. In addition to their rarity, diagnosing these tumors can be challenging given the histologic overlap among various subtypes, their morphologic heterogeneity, and the recent recognition of new entities.

OBJECTIVE

To provide an overview of 4 salivary gland malignancies that we often see in consultation, with a focus on essential diagnostic features and the importance of reporting pertinent diagnostic information to ensure appropriate clinical management.

DATA SOURCES

Review of the literature, supplemented by the personal experience of the authors, which is based on their respective institutional experiences and consultation services.

CONCLUSIONS

When diagnosing carcinoma ex pleomorphic adenoma, pathologists must report several important pieces of information to allow for optimal clinical management. In addition to histologic subtype, the degree of differentiation as well as the degree of invasion, if any, must be reported because all have prognostic relevance. Polymorphous low-grade adenocarcinoma can be a challenging diagnosis on biopsy specimens. Evaluation of the tumor periphery and nuclear features should lead to the correct diagnosis in most cases. Salivary duct carcinoma is an aggressive malignancy characterized by histologic resemblance to breast carcinoma, high-grade cytologic features, and expression of androgen receptor. Benign and malignant myoepithelial neoplasms have a broad morphologic spectrum, and immunohistochemistry is important in reaching the correct diagnosis.

New variants of epithelial-myoepithelial carcinoma: oncocytic-sebaceous and apocrine

CONTEXT

Recently described variants of epithelial-myoepithelial carcinoma have not been well characterized but raise a distinct set of differential diagnostic considerations than the classic type.

OBJECTIVE

To report a detailed analysis of oncocytic-sebaceous epithelial-myoepithelial carcinoma (OEMCa) and a similar, but novel, variant, apocrine epithelial-myoepithelial carcinoma (ApEMCa).

DESIGN

Clinical, histologic, and immunophenotypic features of 5 OEMCas and 5 ApEMCas were analyzed. Ultrastructural examination was also performed on 3 OEMCa and 1 ApEMCa tumors.

RESULTS

The mean age for OEMCa (74.4 years; range, 58-82 years) was slightly higher than for ApEMCa (61.6; range, 46-79 years). All tumors arose in the parotid glands and demonstrated a multinodular pattern of growth with an average size of 3.3 cm (range, 2.3-6.5 cm). Available follow-up (n = 6; 3 OEMCas, 3 ApEMCas) shows a favorable course (no evidence of disease; mean, 17.4 months). Both were morphologically similar, but only OEMCa had sebaceous elements. Phosphotungstic acid hematoxylin staining, antimitochondrial antibody immunohistochemistry, and ultrastructural examination confirm the abundance of mitochondria in OEMCa but not in ApEMCa. The ductal component in ApEMCa was distinguished from that of OEMCa by apical snouts, intracytoplasmic vacuoles, nuclear pleomorphism, prominent nucleoli, and androgen receptor immunoreactivity.

CONCLUSIONS

Oncocytic-sebaceous epithelial-myoepithelial carcinoma and ApEMCa should be considered in the differential diagnosis of oncocytic/oncocytoid salivary gland tumors. Oncocytic-sebaceous epithelial-myoepithelial carcinoma morphology may reflect a senescent phenotype, similar to other oncocytic lesions. The ductal component of ApEMCa shares some similarities with salivary duct carcinoma and supports the notion that epithelial-myoepithelial carcinoma can serve as the progenitor tumor for hybrid tumors.