Dedifferentiated epithelial-myoepithelial carcinoma: analysis of a rare entity based on a case report and literature review

Epithelial-Myoepithelial Carcinoma of the Maxilla Arising From Minor Salivary Glands of Hard Palate: A Rare Case Report

Epithelial-myoepithelial carcinoma is a rare malignant neoplasm of salivary glands. It is specifically found in the major salivary glands. The cases that emerge from minor salivary glands are rarely described. Histologically, it commonly exhibits a characteristic biphasic pattern consisting of epithelial and myoepithelial components. The histopathological resemblance to other benign and malignant neoplasms that also display myoepithelial characteristics makes the differential diagnosis challenging. Each differential diagnosis requires a very different management approach. Considering the difficulties of anatomopathological diagnosis and the rarity of epithelial-myoepithelial carcinomas emerging from minor salivary glands, we report a rare epithelial-myoepithelial carcinoma case of minor salivary glands in a 58-year-old woman. She was referred for a palatal swelling, evolving for more than 35 years, and reported recent pain and nasal obstruction. The mucosal swelling was located in the left maxilla within the hard palate, of a 45-mm-long axis crossing the medial line and extending to the premaxilla, without cervical lymph node involvement. A computed tomography scan revealed a palatal lesion involving the left and the right maxilla. Furthermore, the superior alveolar process, both left and right maxillary sinuses, the nasal cavities, and the nasal septum were included in the lesion. The final diagnosis was difficult to confirm despite multiple biopsies and was determined only from the excised specimen. The diagnosis of this tumor was challenging due to the clinical and histological similarities with other salivary tumors. The aim of this case report is to shed light on the distinctive features of these tumors and explore optimal screening and related management strategies.

Histopathological Aspects of the Prognostic Factors for Salivary Gland Cancers

Salivary gland cancers (SGCs) are diagnosed using histopathological examination, which significantly contributes to their progression, including lymph node/distant metastasis or local recurrence. In the current World Health Organization (WHO) Classification of Head and Neck Tumors: Salivary Glands (5th edition), malignant and benign epithelial tumors are classified into 21 and 15 tumor types, respectively. All malignant tumors have the potential for lymph node/distant metastasis or local recurrence. In particular, mucoepidermoid carcinoma (MEC), adenoid cystic carcinoma (AdCC), salivary duct carcinoma, salivary carcinoma, not otherwise specified (NOS, formerly known as adenocarcinoma, NOS), myoepithelial carcinoma, epithelial-myoepithelial carcinoma, and carcinoma ex pleomorphic adenoma (PA) are relatively prevalent. High-grade transformation is an important aspect of tumor progression in SGCs. MEC, AdCC, salivary carcinoma, and NOS have a distinct grading system; however, a universal histological grading system for SGCs has not yet been recommended. Conversely, PA is considered benign; nonetheless, it should be cautiously treated to avoid the development of metastasizing/recurrent PA. The aim of this review is to describe the current histopathological aspects of the prognostic factors for SGCs and discuss the genes or molecules used as diagnostic tools that might have treatment target potential in the future.

Epithelial-myoepithelial carcinoma of the maxillofacial and sinonasal region: a systematic review of presenting characteristics, treatment modalities, and associated outcomes

Epithelial-myoepithelial carcinoma (EMC) is a rare salivary gland malignancy. Controversy exists in the literature regarding the effectiveness of treatment modalities employed in the management of EMC. This systematic review was undertaken to understand the presenting characteristics of EMC and identify the most common treatment modalities and their associated outcomes, in order to help guide an evidenced-based approach to the algorithm of care. The MEDLINE (PubMed) and Embase databases were searched (up to February 23, 2022), and the review was performed in accordance with the PRISMA statement. Fifty-seven studies (51 case reports and six case series) describing 91 cases of EMC were included in this review. In the included studies, a slow-growing painless mass was the most common presenting clinical feature. EMC was most frequently treated with surgery alone (65%). Local disease recurrence occurred in 24% of the cases and metastatic disease in 11%. A positive surgical margin was found to be associated with a higher risk of recurrence (P < 0.001), while adjuvant radiotherapy was associated with a decreased risk of local disease recurrence (P = 0.034). Metastatic disease and multimodal therapy were found to be associated with decreased disease-free and overall survival (all P < 0.05). The current literature supports surgery with clear margins as the mainstay of treatment for EMC of the salivary and seromucous glands of the head and neck. In certain situations, radiotherapy may improve disease-free survival.

High-grade Transformation/Dedifferentiation in Salivary Gland Carcinomas: Occurrence Across Subtypes and Clinical Significance

High-grade transformation (HGT) or dedifferentiation has been described in a variety of salivary gland carcinomas, including acinic cell carcinoma, secretory carcinoma, adenoid cystic carcinoma, epithelial-myoepithelial carcinoma, polymorphous adenocarcinoma, low-grade mucoepidermoid carcinoma, and hyalinizing clear cell carcinoma. High-grade (HG) transformed tumors are composed of a conventional low-grade component characterized by specific microscopic and immunohistochemical features for the given entity, intermingled with or juxtaposed to areas of HG morphology. This is usually either poorly differentiated adenocarcinoma, carcinoma not otherwise specified, or undifferentiated carcinoma, in which the original line of differentiation is lost. The HG component is composed of solid nests of anaplastic cells with large vesicular pleomorphic nuclei, prominent nucleoli, and abundant cytoplasm. Frequent mitoses and extensive necrosis may be present. The Ki-67 labeling index is consistently higher in the HG component. The molecular genetic mechanisms responsible for HGT of salivary gland carcinomas are largely unknown, though p53 inactivation and human epidermal growth factor receptor 2 overexpression and/or gene amplification have been demonstrated in the HG component in a few examples, the frequency varies for each histologic type. Salivary gland carcinomas with HGT are more aggressive than conventional carcinomas, with a higher local recurrence rate and a poorer prognosis. They have a high propensity for cervical lymph node metastasis suggesting a need for a wider resection and neck dissection. HGT of salivary gland carcinoma can occur either at initial presentation or less commonly at the time of recurrence, sometimes following postoperative radiotherapy. The potential for HGT in almost any type of salivary gland carcinoma warrants a thorough sampling of all salivary gland malignancies to prevent oversight of a HG component.

Dedifferentiation of oncocytic epithelial-myoepithelial carcinoma to mucoepidermoid carcinoma in parotid gland: A rare case report

Epithelial-myoepithelial carcinomas (EMCs) account for <1% of all salivary gland malignancies. Till now, 23 cases of dedifferentiated EMC have been reported to the best of our knowledge. However, dedifferentiation of oncocytic EMC to mucoepidermoid carcinoma is extremely rare. A 38-year-old female presented with right post aural swelling 4 cm × 2 cm in size for 6 months. Surgical excision was carried out, and we received partly skin-covered tissue 5 cm × 2 cm in size. Sections examined showed features of oncocytic EMC dedifferentiating into mucoepidermoid carcinoma. Myoepithelial component showed oncocytic change which was highlighted by p63.

Epithelial-myoepithelial carcinoma with high-grade transformation of parotid gland: A case report and literature review

RATIONALE

Epithelial-myoepithelial carcinoma (EMC) is regarded as a rare low-grade malignant tumor of the salivary gland, accounting for 0.4% to 1% of all salivary gland tumors. However, epithelial-myoepithelial carcinoma with high-grade transformation (EMC with HGT) is extremely rare, therefore it is easily to be inappropriately diagnosed and treated. Herein, we report an unusual case of EMC with HGT involving the parotid gland and discuss the clinical features and histological characteristic of EMC with HGT, in order to remind the doctors to take appropriate diagnosis and treatment.

PATIENT CONCERNS

A 77-year-old female sought for treatment in our hospital due to pain mass in the left parotid gland for 6 months with rapid growth recently.

DIAGNOSES

EMC with HGT was confirmed by final pathology, and then the result showed there were 2 distinctly different areas in the tumor, including the typical EMC component and intensive spindle cells component.

INTERVENTIONS

The extensive resection surgery was performed.

OUTCOMES

The patient was uneventful after surgery and no recurrence or metastasis has been observed after follow-up of 4 years.

LESSONS

A review of literature suggested that EMC with HGT patients trend to be more aged, more aggressive and poorer prognosis than typical EMC patients. In order to avoid misdiagnosis and inappropriate treatment, it is necessary to accurately recognize the differences between the EMC with HGT and typical EMC.

Cytomorphologic Attributes of Epithelial Myoepithelial Carcinoma of Nasal Cavity - A Rare Tumor with Unusual Clinical Presentation

Epithelial-Myoepithelial Carcinoma (EMC) is a rare low grade epithelial malignancy of major Salivary Glands (SG). Though the histomorphology of this tumor is distinct, unusual location and clinical presentation may pose diagnostic difficulties especially when this lesion is first encountered at cytology. We report a case of 60-year-old female presenting with nasal obstruction of three months duration. At FNAC the diagnosis of EMC was suggested and it was confirmed on histopathology. We present this case highlighting the cytomorphologic attributes of this rare tumor occurring at an extremely uncommon location - Nasal cavity.

High-grade epithelial-myoepithelial carcinoma of the parotid gland with mucous cell differentiation

Epithelial-myoepithelial carcinoma (EMC) is a rare salivary gland tumor with a low-grade malignancy, and EMC with high-grade histopathological features is exceedingly rare. Furthermore, EMC with intracellular mucin is also extremely rare. We report an uncommon case of a high-grade EMC of the parotid gland with mucous cell differentiation in a 66-year old Japanese woman who noticed a right palpable parotid mass increasing in size within a one-year period. The cytological specimen showed a focally biphasic structure and included isolated or discohesive piled-up clusters with hyaline globules surrounded by neoplastic cells with nuclear atypia. The gross examination revealed a relatively well-demarcated, multinodular gray-whitish and solid mass. Histologically, the tumor consisted of variably sized solid nests or trabeculae with central necrosis and increased mitotic activity, and invaded into adjacent skeletal muscles. Immunohistochemically, the biphasic ductal and myoepithelial differentiation of this tumor confirmed the diagnosis of high-grade EMC. Furthermore, numerous small nests with d-PAS and alcian blue-positive mucous cells predominated in about 5% of the whole tumor, and these mucous cells were encompassed by neoplastic myoepithelial cells. We should recognize this variant of EMC because we can't rule out the possibility of EMC even in the presence of mucous cells.

Primary epithelial-myoepithelial carcinoma of the lung: A case report demonstrating high-grade transformation-like changes

Primary salivary gland-type tumors of the lung are rare; among them, epithelial-myoepithelial carcinomas (EMC) represent a minor histological subtype. The present case documents an EMC that occluded the B8 segment of the left lung in a 72-year-old woman. Macroscopically, the tumor was well-demarcated; however, microscopic examination demonstrated that it had infiltrated the lung parenchyma. The majority of the tumor mass was composed of a myoepithelial overgrowth in conjunction with conventional bilayered ductal structures comprising epithelial and myoepithelial cells. At the advancing edge of the tumor, the myoepithelial overgrowth was observed to be gradually transitioning to a higher-grade component, which demonstrated venous invasion. The Ki-67 labeling index was reduced compared with high-grade transformation (HGT) of salivary gland EMC; p53 was sparsely observed on immunostaining. However, cyclin D1, which is reported to be overexpressed in certain subtypes of salivary gland carcinomas with HGT, was overexpressed in the higher-grade component of the tumor, indicating a potential HGT initiation. The surgical margin was tumor free, and no recurrence has been observed for 4 months. A thorough follow-up is required considering the HGT-like changes and venous invasion of the tumor. Additional studies are required to elucidate the characteristics of pulmonary EMC, with an emphasis on detecting HGT or HGT-like changes.

Global transcriptome and sequenome analysis of formalin-fixed salivary epithelial-myoepithelial carcinoma specimens

Diverse microarray and sequencing technologies have been widely used to characterize molecular changes in malignant epithelial cells in salivary neoplasms. Such gene expression studies to identify markers and targets in tumor cells are, however, compromised by the cellular heterogeneity of these tumors and by the difficulties to accrue matching controls representing normal salivary glands. Seventeen samples of primary salivary epithelial-myoepithelial carcinoma along with tissue from six normal major salivary glands were microdissected from paraffin-embedded tissue. Pools of RNA from highly enriched preparations of these cell types were subjected to expression profiling using a whole-transcriptome shotgun sequencing experiment. In parallel, extracted genomic DNA was used for the 50 gene hotspot panel sequenome. KRAS mutations in three patients (18%), NRAS mutations in one patient (6%), but no HRAS, MET, PIK3CA, or BRAF mutations. Using strict and conservative criteria, 220 differentially expressed transcripts were found, with 36% up- and 64% downregulated. The transcripts were annotated using NCBI Entrez Gene, and computationally analyzed with the Ingenuity Pathway Analysis program. From these significantly changed expressions, the analysis identified 26 cancer-related transcripts and 16 transcripts related to mitochondrial dysfunction overlapping with three cancer-related genes. These 220 differentially expressed genes including microRNAs provide here a sufficiently large set to specifically define epithelial-myoepithelial carcinoma and to identify novel and potentially important targets for diagnosis, prognosis, and therapy of this cancer.

Case study of a parotid gland adenocarcinoma dedifferentiated from epithelial-myoepithelial carcinoma

Dedifferentiation is defined as high-grade malignant tumor development out of a low-grade malignant tumor. We present an adenocarcinoma tumor of the parotid gland that was dedifferentiated from a low-grade epithelial-myoepithelial carcinoma and was followed up for 3 years. Our patient, a 46-year-old female, presented with a left parotid mass of 20-year duration. Histopathologic results showed that there was only one area of typical epithelial-myoepithelial carcinoma, with foci of poorly differentiated adenocarcinoma (not otherwise specified; NOS) and clear cytoplasm in the parotid gland. Immunohistochemical staining results showed SMA (+), P63 (+), CK8 (+), and S100 (+) on epithelial cells. A review of the literature revealed 22 previously reported cases of dedifferentiated epithelial-myoepithelial carcinoma. In these cases, the malignant tumors that dedifferentiated from epithelial-myoepithelial carcinoma were adenoid cystic carcinoma, actinic cell carcinoma, polymorphous low-grade adenocarcinoma, mucoepidermoid carcinoma, and intraductal carcinoma. In our case, the malignant tumor that dedifferentiated from the epithelial-myoepithelial carcinoma was a poorly differentiated adenocarcinoma. Histopathological results showed that metastases were not seen in the neck-dissection material. As a result, our case will make a contribution to the literature in terms of prognosis, because there are very few reported cases of dedifferentiated adenocarcinoma development arising from epithelial-myoepithelial carcinoma.

Epithelial-myoepithelial carcinoma of the parotid gland: Clinicopathological aspect, diagnosis and surgical consideration

The present paper describes the clinical and pathological features of epithelial-myoepithelial carcinoma (EMC) of the parotid gland. This rare tumor represents <1% of all salivary gland tumors and arises most commonly in the parotid gland, but it has also been described in the submandibular gland, minor salivary glands and palate. EMC is considered to be a low-grade malignant tumor that may commonly recur locally after resection in 23-50% of cases. The complex and varied morphological expression of this neoplasm has attracted numerous investigators, who have presented valuable but often contradictory data. After an in-depth analysis of the clinicopathological aspects of EMC, we speculate that adequate resection with negative soft-tissue margins is the minimum recommended and necessary therapy.

Clinical outcome of patients with carcinoma ex pleomorphic adenoma of the parotid gland: a comparative study from a single tertiary center

BACKGROUND

Carcinoma ex pleomorphic adenoma (CXPA) of the parotid gland is a high-grade cancer and the prognosis of this cancer has not been compared with non-CXPA high-grade primary parotid cancer.

METHODS

Retrospective medical chart review of patients with surgically treated high-grade primary parotid cancer (21 CXPA and 52 non-CXPA) was performed with correlation with disease-specific survival, locoregional recurrence, and distant recurrence.

RESULTS

Despite having similar stage of cancer and extent of surgical resection, patients with CXPA had a lower disease-specific survival compared to non-CXPA high-grade primary parotid cancer (p = .02). Salivary duct cancer (SDC) was the commonest histologic variant in both cohorts and around 40% of patients with SDC died of distant recurrence that occurred within 3 years from diagnosis.

CONCLUSION

CXPA of the parotid gland is a more aggressive cancer compared to non-CXPA high-grade primary parotid cancer. SDC was associated with a high chance of delayed distant recurrence, which contributed directly to the mortality of this cancer.

"Dedifferentiation" and high-grade transformation in salivary gland carcinomas

"Dedifferentiation" and/or high-grade transformation (HGT) has been described in a variety of salivary gland carcinomas, including acinic cell carcinoma, adenoid cystic carcinoma, epithelial-myoepithelial carcinoma, polymorphous low-grade adenocarcinoma, myoepithelial carcinoma, low-grade mucoepidermoid carcinoma and hyalinizing clear cell carcinoma, although the phenomenon is a rare event. Recent authors tend to preferably use the term HGT instead of "dedifferentiation" in these cases. HGT-tumors are composed of conventional carcinomas juxtaposed with areas of HG morphology, usually either poorly differentiated adenocarcinoma or "undifferentiated" carcinoma, in which the original line of differentiation is no longer evident. The HG component is generally composed of solid nests, sometimes occurring in cribriform pattern of anaplastic cells with large vesicular pleomorphic nuclei, prominent nucleoli and abundant cytoplasm. Frequent mitoses and extensive necrosis is evident. The Ki-67 labeling index is consistently higher in the HG component. p53 abnormalities have been demonstrated in the transformed component in a few examples, but the frequency varies by the histologic type. HER-2/neu overexpression and/or gene amplification is considerably exceptional. The molecular-genetic mechanisms responsible for the pathway of HGT in salivary gland carcinomas largely still remain to be elucidated. Salivary gland carcinomas with HGT have been shown to be more aggressive than conventional carcinomas with a poorer prognosis, accompanied by higher local recurrence rate and propensity for cervical lymph node metastasis, suggesting the need for wider resection and neck dissection.

Oncocytic and apocrine epithelial myoepithelial carcinoma: novel variants of a challenging tumor

Epithelial myoepithelial carcinoma (EMCa) is a rare but well characterized biphasic salivary gland malignancy with several variant morphologies. Oncocytic and apocrine EMCa are uncommon variants that constitute up to 8 % of all EMCa. Both variants invoke an eosinophilic or oncocytic differential diagnosis and challenge the traditional requirement of clear myoepithelial cells for EMCa. Oncocytic EMCa occurs in patients a decade older than conventional EMCa. This variant is often papillary with calcification and associated with sebaceous components and occurs in older individuals. Apocrine EMCa is named for its apocrine ductal component, which may be mistaken for salivary duct carcinoma. In this variant, the epithelial component often shows overgrowth in a cribriform or even solid pattern and is immunophenotypically defined by androgen receptor and gross cystic disease fluid protein 15 positivity. The most important aspect of differentiating both oncocytic and apocrine EMCa from other salivary oncocytic tumors is recognition of the biphasic nature of these variants and confirmation that the abluminal outer layer consists of plump, 'activated' myoepithelial cells, regardless of tinctorial characteristics. Both oncocytic and apocrine EMCa behave very indolently in the limited literature to date.