Myoepithelial Carcinoma of the Salivary Glands: A Clinicopathologic Study of 29 Patients

Carcinomas with clear cell features and EWSR1 rearrangements: a report of 3 cases

Salivary gland and odontogenic neoplasms with extensive clear cell change are rare lesions but have been increasingly characterized over the past decade. Among this heterogeneous group of neoplasms, hyalinizing clear cell carcinoma (HCCC), clear cell odontogenic carcinoma (CCOC), and clear cell myoepithelial carcinoma (CCMC) share a monophasic clear cell morphology and an EWSR1 gene rearrangement. While HCCC is relatively well characterized, there are a limited number of EWSR1-reaarranged CCMC of salivary glands reported, and its clinicopathologic features in relation to HCCC and nonclear cell myoepithelial carcinoma (MC) have not been clarified. This report describes the clinical, morphologic, and immunophenotypic features of 3 carcinomas composed predominantly of clear cells and with EWSR1 rearrangements by fluorescence in situ hybridization. A comparative literature analysis suggests that HCCC, CCMC, and nonclear cell MC of salivary glands are clinically, histopathologically, and molecularly distinct.

Clinicopathological features and prognostic factors of salivary gland myoepithelial carcinoma: institutional experience of 42 cases

Myoepithelial carcinoma (MECA) is a rare type of carcinoma for which the clinicopathological features and prognostic factors have not yet been fully clarified. A retrospective study of 42 patients diagnosed with salivary gland MECA was performed, focusing on the clinicopathological features and prognostic factors. Of the 42 patients, 20 died of cancer, 20 lived without tumour, one lived with distant metastasis, and one was lost to follow-up. Overall, 69.0% had tumour recurrence, 16.7% had cervical nodal metastasis, and 21.4% had distant metastasis. The 5-year overall survival rate was 70.2%. Kaplan-Meier analysis revealed that patients with pathological positive lymph nodes (pN+), multiple recurrences of tumour, and higher histological grade had worse overall survival. Multivariate Cox analysis indicated pN+ and higher histological grade to be independent predictors of decreased survival. The 5-year overall survival rate in the pN0 group was 87.5%, while that in the pN+ group was 28.6%. In conclusion, myoepithelial carcinoma can be defined as a tumour with a high incidence of recurrence and poor prognosis, especially in pN+ patients. Pathological positive lymph nodes and histological grade may serve as predictors of survival.

Cytopathology of salivary gland myoepithelial carcinoma: A study of 13 cases and review of the literature

INTRODUCTION

Myoepithelial carcinoma (MECA) is an infrequently recognized salivary gland (SG) neoplasm that commonly develops within a preexisting pleomorphic adenoma (MECA ex PA). Fine-needle aspiration (FNA) biopsy reports of this neoplasm are largely restricted to small series and single case reports.

METHODS

Our cytopathology files were searched for examples of SG MECA/MECA ex PA having confirmatory histopathologic verification. Conventional FNA biopsy smears were performed, and exfoliative specimens processed using standard techniques.

RESULTS

Thirteen cases from 9 patients (M:F = 3.5:1; age range: 36 to 95 years, mean age = 60 years) met inclusion criteria. FNA biopsy sites included parotid gland (4), trunk (2), scalp (2), and neck (2). Exfoliative specimens included pleural fluid (1), bronchial brushing (1), and bronchoalveolar lavage (1). Most cases were metastatic deposits (8; 62%), 4 were primary neoplasms, and 1 a local recurrence. FNA diagnoses were MECA ex PA (6; 46%), myoepithelial neoplasm (2), PA (2), basaloid neoplasm (1), atypical myoepithelial cells (1), and myxoma (1). Ancillary testing in 2 cases showed positive staining for myoepithelial markers. Cytologic features were that of a low-grade neoplasm composed principally of epithelioid/polygonal cells exhibiting minimal if any cytologic atypia. Myxoid and chondromyxoid stroma was often the dominant feature in MECA ex PA aspirates.

CONCLUSION

In the primary setting, a cytologic diagnosis of MECA/MECA ex PA is extremely challenging if at all possible. Due to overwhelming amounts of stroma, the diagnosis may be challenging in some cases of metastatic MECA ex PA.

Clinicopathological and survival profile of patients with salivary gland myoepithelial carcinoma: A systematic review

OBJECTIVES

In this systematic review, we aimed to evaluate the clinicopathological and prognosis data of patients with salivary gland myoepithelial carcinoma.

MATERIALS AND METHODS

MEDLINE/PubMed, Scopus, and Embase search was performed with the keywords "myoepithelial carcinoma" "malignant myoepithelioma," and "salivary glands." Primary salivary glands myoepithelial carcinoma that fulfilled the World Health Organization diagnostic criteria were included. The Joanna Briggs Institute tool was used to assess the risk of bias.

RESULTS

Forty-three studies (71 patients) met the inclusion criteria. The patients showed a mean age of 56.4 ± 19.6 years with no sex predilection. The parotid was the most affected gland (49.3%). The tumor presented as an asymptomatic (65.1%) mass (84%). The most common histological findings were the presence of clear tumor cells (39.7%) and multinodular growth patterns (60.7%). Multivariate analysis showed plasmacytoid cell type (p = 0.010) and solid growth pattern (p = 0.003) were related to decreased disease-free survival. Surgery alone was the most used treatment (53.5%). Patients with a combination of treatments showed a longer disease-free survival (p = 0.049). The 2-year and 5-year overall survival rates were 67.5% and 46.1%, respectively.

CONCLUSION

Salivary gland myoepithelial carcinoma showed no sex predilection, with a higher incidence in the parotid gland. Cell type, growth pattern, and treatment type may be related to a lower disease-free survival. Overall, salivary gland myoepithelial carcinoma presented low recurrence and metastasis rates. Registration and protocol: This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 checklist and registered in the International Prospective Register of Systematic Reviews (PROSPERO) database (CRD42022311512).

Myoepithelial carcinoma of major salivary glands: Analysis of population-based clinicopathologic and prognostic features

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The demographic features of major salivary glands myoepithelial carcinoma has been analyzed using propensity score-matching.

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The correlation between tumor stage and prognostic for patients with myoepithelial carcinoma is conformed.

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The radiotherapy is a favorable factor for overall survival in patients with myoepithelial carcinoma.

Background

This study aimed to investigate the effect of demographic characteristics and disease stage on the survival outcomes of patients with myoepithelial carcinoma (MECA) of the salivary glands, and to assess the role of radiotherapy in these patients.

Methods

The Epidemiology, Surveillance and End Results database was queried from 2000 to 2018 to identify patients with MECA. Data pertaining to the tumor stage, size, histological grade, and demographic characteristics were analyzed. The relationship between clinicopathological features and overall survival (OS) was assessed using statistical analyses.

Results

In total, 290 patients (137 men and 153 women) were identified. The parotid gland was the most common tumor location (76.6% patients). Approximately half of the patients had locally advanced tumors, and 14.5 and 6.6% had lymph node and distant organ involvement, respectively. The median OS was 142 months, while the survival rates at 120 months and 180 months were 53% and 39%, respectively. In the cohort, 160 patients (55.2%) underwent surgery alone, while 130 patients (44.8%) underwent surgery combined with radiotherapy. Multivariate Cox analysis revealed that histopathological grade, stage, T3 stage (hazard ratio [HR]: 2.47, P = 0.039), T4 stage (HR: 3.33, P = 0.011), N2 stage (HR: 6.59, P = 0.002), and M1 stage (HR: 2.72, 95%confidence interval [CI]: 1.03–7.19; P = 0.044) were associated with poor prognosis. Radiotherapy (HR: 0.58, P = 0.042) was a favorable factor for OS, and it reduced the mortality risk by 42%.

Conclusions

Histological grade, stage, and radiotherapy are independent risk factors for OS. The decision to administer chemotherapy for MECA should be made with caution. Adjuvant radiotherapy is recommended in high-risk patients.

Esophageal myoepithelial carcinoma: Four case reports

BACKGROUND

Myoepithelial carcinoma (MC) is a rare malignant neoplasm that mainly occurs in the salivary gland. MC can be confused with many other tumors when arising outside the salivary glands because it presents with a wide spectrum of cytomorphological and immunohistochemical features. To the best of our knowledge, esophageal MC has not been previously reported. The purpose of this study was to describe the imaging and clinicopathological features of esophageal MC to improve the understanding of the disease.

CASE SUMMARY

Three men and one woman diagnosed with esophageal MC were enrolled in this study. The primary clinical symptom was dysphagia. The mass was mainly located in the middle esophagus. Laboratory tests revealed that two patients who underwent tumor abnormal protein were positive. Radical resection was performed for all patients with no adjuvant therapy. Hematoxylin-eosin staining showed infiltrative growth of epithelial cells with hyperchromatic and pleomorphic nuclei toward the periphery. Immunohistochemistry showed that all patients were positive for P63, and most patients were positive for SOX-10, AE1/AE3, P40, and calponin. The Ki-67 values were all higher than 60%. Patient one died one month after discharge from an unknown cause. Patient two lost to follow-up. At patient three’s four-month review, enhanced computed tomography (CT) showed anastomosis recurrence and bilateral lung metastases. He abandoned treatment and lost to follow-up. Patient four attended review appointments regularly and remained in a good general condition.

CONCLUSION

Here, we present the first report of esophageal MC and review the relevant literature. Esophageal MC is more likely to occur in the middle esophagus in older patients with male dominance. A fungating type observed on CT scanning may help narrow down the differential diagnosis. Cystic change or necrosis may occur in larger lesions. The final diagnosis should be made according to the pathological examination. The treatment for MC is surgical resection, and the efficacy of chemotherapy needs to be determined with future studies.

Esophageal myoepithelial carcinoma: Four case reports

BACKGROUND

Myoepithelial carcinoma (MC) is a rare malignant neoplasm that mainly occurs in the salivary gland. MC can be confused with many other tumors when arising outside the salivary glands because it presents with a wide spectrum of cytomorphological and immunohistochemical features. To the best of our knowledge, esophageal MC has not been previously reported. The purpose of this study was to describe the imaging and clinicopathological features of esophageal MC to improve the understanding of the disease.

CASE SUMMARY

Three men and one woman diagnosed with esophageal MC were enrolled in this study. The primary clinical symptom was dysphagia. The mass was mainly located in the middle esophagus. Laboratory tests revealed that two patients who underwent tumor abnormal protein were positive. Radical resection was performed for all patients with no adjuvant therapy. Hematoxylin-eosin staining showed infiltrative growth of epithelial cells with hyperchromatic and pleomorphic nuclei toward the periphery. Immunohistochemistry showed that all patients were positive for P63, and most patients were positive for SOX-10, AE1/AE3, P40, and calponin. The Ki-67 values were all higher than 60%. Patient one died one month after discharge from an unknown cause. Patient two lost to follow-up. At patient three’s four-month review, enhanced computed tomography (CT) showed anastomosis recurrence and bilateral lung metastases. He abandoned treatment and lost to follow-up. Patient four attended review appointments regularly and remained in a good general condition.

CONCLUSION

Here, we present the first report of esophageal MC and review the relevant literature. Esophageal MC is more likely to occur in the middle esophagus in older patients with male dominance. A fungating type observed on CT scanning may help narrow down the differential diagnosis. Cystic change or necrosis may occur in larger lesions. The final diagnosis should be made according to the pathological examination. The treatment for MC is surgical resection, and the efficacy of chemotherapy needs to be determined with future studies.

Myoepithelial Carcinoma Ex-Pleomorphic Adenoma: A Rare Pathology Misdiagnosed as Pleomorphic Adenoma; With a Novel TERT Promoter Mutation and High PD-L1 Expression

Myoepithelial carcinoma (MECA) is a rare salivary gland (SG) neoplasm (0.1-0.45% of all SG tumors) that often presents with bland cytomorphology and can be misclassified as cellular pleomorphic adenoma (PA) or myoepithelioma. This is particularly challenging in MECA ex-PA cases, especially if tumor shows minimal to no capsular invasion. We report a rare case of a 76-year-old female; history of left superficial parotidectomy with diagnosis (outside hospital) of cellular PA, who re-presented 9 months post surgery with enlarging left parotid mass, neck lymphadenopathy and facial nerve deficits. FNAB of parotid and neck lymph node revealed cellular aspirates with loosely cohesive clusters of myoepithelial cells with occasional chondromyxoid stroma. Prior resection slides were reviewed, and diagnosis of MECA ex-PA was made. Patient underwent left radical parotidectomy, selective neck dissection, with facial nerve sacrifice (due to extensive encasing by tumor). Histology showed a multinodular tumor with pushing borders, zonal arrangement comprising of a hypocellular, necrotic/myxoid center, and a peripheral rim of myoepithelial cells, confirmed by positive S100, and p63. Tumor extensively infiltrated peri parotid soft tissues with multiple foci of lymphovascular and perineural invasion; and metastatic neck lymph nodes. Next generation sequencing revealed a novel TERT promoter mutation (c.-124C > T), not usually described in SG neoplasms. Further, PD-L1 immunohistochemistry showed positive expression, making patient eligible for anti-PDL-1 immunotherapy. This case highlights importance of recognizing the subtle malignant features of MECA in distinguishing it from benign mimics like PA. In addition, presence of TERT mutation opens a new arena for future research to explore potential treatment targets.

Glial Fibrillary Acidic Protein Expression Helps Distinguish Pleomorphic Adenoma from Histologic Mimics

Pleomorphic adenoma (PA) is the most common biphasic type of salivary gland tumour to arise in adults. It is a biphasic tumour composed of both luminal (ductal) cells and abluminal (basal and myoepithelial) cells. Other biphasic salivary gland type tumours, both benign and malignant, can mimic PA, especially on small biopsies. Previous studies have shown that glial fibrillary acidic protein (GFAP) is preferentially expressed in PA and can be useful in the distinction from other salivary gland tumours. However, most of these studies were performed on a small subset of tumour types at a time when the classification of salivary gland type tumours was less refined. The purpose of this study was to assess the expression of glial fibrillary acidic protein (GFAP) in a broad group of both benign and malignant salivary gland tumours. The expression of GFAP was assessed in 99 tumours including 54 PAs, 5 basal cell adenomas, 1 myoepitheliomas, 5 adenoid cystic carcinomas, 6 epithelial-myoepithelial carcinomas (EMCA), 6 mucoepidermoid carcinomas, 7 salivary duct carcinomas, 1 adenocarcinomas NOS, 2 myoepithelial carcinomas, 4 basal cell adenocarcinomas, 5 acinic cell carcinomas and 3 polymorphous adenocarcinomas. Of the malignant cases, 8 were classified as carcinomas ex PA. GFAP was also assessed in 19 concurrent biopsy specimens. GFAP was expressed in the resections of 51 PAs examined (94%). Expression was predominantly strong and diffusely seen in myoepithelial cells. Strong and diffuse GFAP expression was also seen in two EMCAs (33%) and one myoepithelial carcinoma (50%). On biopsy specimens, 100% of PAs and basal cell adenomas expressed GFAP. GFAP was also seen in 1 out of 3 carcinomas ex PAs on biopsies. Almost all PAs show strong and diffuse expression of GFAP. In contrast, most malignant neoplasms that can mimic PA on biopsies show only rare, focal expression. Other benign tumours composed of abluminal/myoepithelial cells also show focal expression of GFAP, highlighting the spectrum these tumours share with PA. Overall, the presence of strong and diffuse GFAP expression can favour a benign neoplasm, specifically a PA, on limited biopsy specimens.

A tree-based machine learning model to approach morphologic assessment of malignant salivary gland tumors

Malignant salivary gland tumors represent a challenge for pathologists due to their low frequency and morphologic overlap. In recent years machine learning techniques have been applied to the field of pathology to improve diagnostic performance. In the present work, we fitted a machine learning algorithm to approach the diagnosis of malignant salivary gland tumors. Twelve morphologic variables were scored across 115 samples representing the most commonly encountered malignant salivary gland tumors. The sample was randomly split into a discovery and validation set. A recursive partitioning algorithm was used to systematically screen and organize candidate variables into a classification tree using the discovery set. A cross-validation strategy was used to tune the algorithm hyperparameters. Inter-observer concordance was calculated by independent evaluation of 26 randomly selected cases. The five-tiered tree built, required the evaluation of 6 morphological variables. Basaloid appearance, presence of mucous cells, necrosis, cribriform pattern, clear cells and keratinization were selected by the algorithm to build the tree. This diagnostic tool correctly classified 89.9% and 84.6% of the samples in the discovery and validation sets respectively. Misclassification pattern was consistent between both sets. Misclassified tumors belonged to one of three histologic types: epithelial-myoepithelial, polymorphous and mucoepidermoid carcinomas. Other histotypes demonstrated perfect recall in both the discovery and validation sets. Overall inter-observer concordance was good, with median kappa scores between the expert evaluator and training pathologists being 0.81. Overall, our classification tool developed using a recursive partitioning algorithm can effectively guide the morphological approach to malignant salivary gland tumors.

The Decline of Salivary Adenocarcinoma Not Otherwise Specified as a Tumor Entity: Reclassification Using Contemporary Immunohistochemical Profiling and Diagnostic Criteria

The classification of salivary gland carcinomas has become increasingly specific over the last decade with the definition of new tumor types, documentation of novel molecular and immunohistochemical findings, and development of more refined diagnostic criteria. In this setting, it is unclear how many salivary tumors still cannot be easily categorized-and whether such tumors represent undifferentiated malignancies or include additional definable entities. Relying largely on current classification schemes and contemporary immunohistochemical panels, we reassessed salivary tumors previously diagnosed as adenocarcinoma, not otherwise specified (ACA NOS) from 2 large academic medical centers. Fifty-seven ACA NOS (72%) could be reclassified as more specific entities including 31 salivary duct carcinomas (39%), 7 polymorphous adenocarcinomas (9%), 5 epithelial-myoepithelial carcinomas (6%), 4 myoepithelial carcinomas (5%), 4 secretory carcinomas (5%), 1 acinic cell carcinoma (1%), 1 basal cell adenocarcinoma (1%), 1 intraductal carcinoma (1%), and 1 clear cell carcinoma (1%) as well as 2 metastatic squamous cell carcinomas (3%). Of reclassified cases, 21 (37%) represented variant histologies within these categories. ACA NOS comprised 11% of salivary malignancies before reclassification, but only 4% after reclassification. The remaining 22 ACA NOS demonstrated heterogeneous features, with an association between histologic grade and clinical outcome. In effect, ACA NOS is becoming a bygone entity as modern classification schemes and ancillary techniques now permit more specific typing of a majority of these tumors, potentially facilitating more specific prognostication and treatment. Additional distinctive entities such as mucinous adenocarcinoma may still be definable within the ACA NOS category.

Molecular Profiling of Clear Cell Myoepithelial Carcinoma of Salivary Glands With EWSR1 Rearrangement Identifies Frequent PLAG1 Gene Fusions But No EWSR1 Fusion Transcripts

Myoepithelial carcinoma of salivary glands is an underrecognized and challenging entity with a broad morphologic spectrum, including an EWSR1-rearranged clear cell variant. Myoepithelial carcinoma is generally aggressive with largely unknown genetic features. A retrospective review of Salivary Gland Tumor Registry in Pilsen searching for the key words "clear cell myoepithelial carcinoma," "hyalinizing clear cell," and "clear cell malignant myoepithelioma" yielded 94 clear cell myoepithelial carcinomas (CCMCs) for molecular analysis of EWSR1 rearrangement using fluorescence in situ hybridization (FISH). Tumors positive for EWSR1 gene rearrangement were tested by next-generation sequencing (NGS) using fusion-detecting panels. NGS results were confirmed by reverse-transcription polymerase chain reaction or by FISH. Twenty-six tumors originally diagnosed as CCMC (26/94, 27.6%) revealed split signals for EWSR1 by FISH. Six of these tumors (6/26, 23%) displayed amplification of the EWSR1 locus. Fifteen cases were analyzable by NGS, whereas 9 were not, and tissue was not available in 2 cases. None of the CCMCs with EWSR1 rearrangements detected by FISH had an EWSR1 fusion transcript. Fusion transcripts were detected in 6 cases (6/15, 40%), including LIFR-PLAG1 and CTNNB1-PLAG1, in 2 cases each, and CHCHD7-PLAG1 and EWSR1-ATF1 fusions were identified in 1 case each. Seven cases, including those with PLAG1 fusion, were positive for PLAG1 rearrangement by FISH, with notable exception of CHCHD7-PLAG1, which is an inversion not detectable by FISH. One single case with EWSR1-ATF1 fusion in NGS showed ATF1 gene rearrangement by FISH and was reclassified as clear cell carcinoma (CCC). In addition, another 4 cases revealed ATF1 rearrangement by FISH and were reclassified as CCC as well. Moreover, 12/68 (17%) CCMCs with intact EWSR1 gene were selected randomly and analyzed by NGS. PLAG1 fusions were found in 5 cases (5/12, 41.6%) with LIFR (2 cases), FGFR1 (2 cases), and CTNNB1 (1 case) as partner genes. Overall, PLAG1 gene rearrangements were detected in 10/38 (26%) tested cases. None of the tumors had SMARCB1 loss by immunohistochemistry as a possible explanation for the EWSR1 abnormalities in FISH. Novel findings in our NGS study suggest that EWSR1-FISH positive CCMC is a gene fusion-driven disease with frequent oncogenic PLAG1 fusions, including LIFR-PLAG1 and CTNNB1-PLAG1 in most cases. Productive EWSR1 fusions are found only in a minority of EWSR1-ATF1-rearranged cases, which were in part reclassifiable as CCCs. Detectable EWSR1-FISH abnormality in CCMCs without gene fusion perhaps represents a passenger mutation with minor or no oncologic effect.

NUT Carcinoma Arising from the Parotid Gland: A Case Report and Review of the Literature

NUT carcinoma is an aggressive carcinoma with an overall poor survival outcome. The mediastinum and head and neck area, especially the sinonasal region, are among the common sites of disease. Histopathological diagnosis of NUT carcinoma is often very challenging due to its overlapping features with other poorly differentiated carcinomas. We report a case of NUT carcinoma arising from the parotid gland of a young female patient. Primary NUT carcinoma of salivary gland is very rare, with only 15 such cases reported in the literature to date. Our case highlights the diagnostic challenges associated with such lesions.

Myoepithelial Tumors of Salivary Gland: A Clinicopathologic and Immunohistochemical Study of 15 Patients with MIB-1 Correlation

Myoepithelial neoplasms are rare tumors of the salivary glands with predominant myoepithelial differentiation and a broad histologic spectrum. Their histological features, immunohistochemical profile and biological behavior are not well characterized and pose a diagnostic challenge. A total of 15 myoepithelial tumors, diagnosed during 2012 and 2019 were subcategorized and correlated with MIB-1 labeling index (LI) and various histological parameters. Immunohistochemical stains for MIB-1 and other antibodies were performed. Statistical analysis was done by chi-square test, Fisher's exact test and Kaplan Meier curve. Nine patients were male and six were female with the median age of 44 years (range 21-83 years). Of the 15 patients, 6 cases were classified as myoepithelioma (ME) and 9 cases as myoepithelial carcinoma (MECA). Parotid gland was the most common site (46.7%) followed by the palate. MEs showed well circumscribed tumor borders whereas MECAs exhibited focal capsular to extensive invasion into adjacent tissues. Epithelioid cell morphology was most common followed by mixed cell morphology. MIB-1 LI was significantly associated with invasive tumor borders, necrosis and high mitosis. Increased frequency of recurrence was noted with high MIB-1 LI, though it was not statistically significant. MIB-1 LI was high in nearly all MECAs with focal capsular to extensive invasion while low in MEs. Myoepithelial tumor with multinodular growth pattern and focal capsular invasion may have an indolent behavior if mitotic activity and MIB-1 LI is low. Early diagnosis and treatment of MECAs significantly improves the patient's survival and prognosis.

Metastatic Cutaneous Basal Cell Carcinoma: Report of 2 Cases Preceding the Hedgehog Pathway Antagonists Era

Basal cell carcinoma (BCC) of the skin is the most common type of malignant human tumor. However, metastatic BCC is a very rare event with weakly effective therapeutic options and a poor prognosis, until a few years ago. In 2012, small-molecule therapies, capable of inactivating the hedgehog signaling pathway and thus reducing tumor growth and progression, were introduced into clinical practice for the treatment of patients with advanced BCC. We present retrospectively 2 personal cases of metastatic BCC of the skin, from the premolecular therapy era, from primary tumors that arose years before in the head and neck area. The former case occurred in a 45-year-old woman with a history of recurrent BCC of the retroauricular skin who eventually died due to diffuse metastatic spread. The latter case concerned a 70-year-old man also with a history of recurrent BCC of the nasal-perinasal skin who developed multiple subcutaneous and lymph node metastases in the neck. In both cases, the diagnoses were based on biopsies of the metastatic sites. The first patient died 5 months after the diagnosis of metastatic disease, while the second was alive and disease-free 2 years after neck lymph node dissection and external radiation therapy, and then lost to follow-up. We extensively discuss several tumor entities with basal or basaloid features that may enter the differential diagnosis with BCC in metastatic sites. In addition, we briefly summarize the advances in clinical therapeutics using small molecules, which are now an integral part of the treatment of such advanced BCC cases.

Misinterpreted Myoepithelial Carcinoma of Salivary Gland: A Challenging and Potentially Significant Pitfall

Myoepithelial carcinoma (MECA) is an underrecognized challenging entity with a broad morphologic spectrum. Misinterpreting MECA is not uncommon as distinguishing it from its mimics, especially cellular myoepithelial-rich pleomorphic adenoma (PA), can be difficult. We described 21 histologically challenging cases of MECAs (16 MECA ex-PA and 5 MECA de novo). All MECAs ex-PA were intracapsular or minimally invasive except for 3 cases. Eighteen (86%) were initially misinterpreted as benign neoplasms, including PA (10), atypical PA (5), and myoepithelioma (3). The remaining 3 were initially diagnosed as malignant (MECA ex-PA) but were histologically challenging. Histologic features that were found most helpful in recognizing the malignant nature of MECA included: uniformly cellular myoepithelial proliferation with an expansile nodular lobulated pattern (all cases) and alternate hypocellular and hypercellular zonal distribution (76% of cases). Among the 16 MECA patients with follow-up, 14 (87.5%) progressed: 10 developed local recurrence and 5 distant metastases. In contrast, only one of 33 patients with cellular PA (control group) recurred locally. Ten of the 14 MECAs that progressed were MECA ex-PA, and 12 (85%) had an initial benign diagnosis. Two patients with MECA ex-PA died of their disease; one had an initial diagnosis of PA. MECA is a histologically challenging entity that closely mimics PA and seems to carry a significant risk of recurrence. Areas of clonal appearing cellular myoepithelial growth with an expansile nodular lobulated pattern and zonal cellular distribution distinguish the majority of MECAs and may serve as useful diagnostic histologic features to differentiate MECA from its benign mimics.

3D printed titanium prosthesis reconstruction following subtotal maxillectomy for myoepithelial carcinoma - a case report

We present the case of a 43 year old male with a myoepithelial carcinoma of the hard palate who underwent a subtotal maxillectomy, resulting in a significant midfacial defect. The defect was successfully reconstructed with a titanium prosthesis using Additive Manufacturing (AM), better known as 3D printing; the process used to manufacture the prosthesis being Direct Metal Laser Sintering (DMLS). A maxillary denture was fitted onto the titanium DMLS frame post-operatively. This method of reconstruction of a large midfacial defect proved to be successful both functionally and cosmetically, and resulted in a good quality of life 3 years post-operatively.

The key radiologic and cytomorphologic features of oncocytic and oncocytoid lesions of the salivary gland

Oncocytic and oncocytoid lesions represent a distinct subset of salivary gland lesions. True oncocytic lesions of the salivary gland are entirely composed of oncocytes. These are characterized by the presence of abundant eosinophilic granules due to the presence of abundant cytoplasmic mitochondria. Oncocytic lesions of the salivary gland include oncocytosis, oncocytoma, and oncocytic carcinoma. In addition to the true oncocytic lesion, there exists another group of salivary gland lesions, which demonstrate cells with abundant and occasionally granular cytoplasm. These are often termed as "oncocytoid" lesions. The recently proposed Milan System for reporting salivary gland cytology clearly states that fine-needle aspiration specimens representing oncocytic/oncocytoid lesions of salivary gland cannot effectively distinguish between a nonneoplastic lesion, benign and malignant neoplasms. Therefore, most lesions lacking classic cytomorphologic features will be classified under the umbrella diagnostic term of "Salivary Gland Neoplasm of Uncertain Malignant Potential" (SUMP). In this review, we discuss and illustrate key clinicopathologic and radiologic features that can help the practicing cytopathologist narrow down the differential and provide the best management based diagnosis.

Clear Cell Myoepithelial Carcinoma Arising from the Hard Palate with Metastasis to the Lungs

Myoepithelial carcinoma is an uncommon tumor of the salivary glands, most commonly the parotid gland. Clear cell myoepithelial carcinoma is a rare variant with an aggressive behavior. Here, we describe a case of clear cell myoepithelial carcinoma arising from the hard palate in an elderly male who underwent resection of the tumor and postop radiation. Posttreatment imaging demonstrated bilateral pulmonary nodules and a C2 body lesion concerning for metastasis. Biopsy of the lung lesions revealed a monomorphous population of optically clear cells with hyperchromatic and pleomorphic nuclei which were morphologically similar to the prior resection specimen. There are few reported cases of clear cell myoepithelial carcinoma arising from the hard palate, and there are even fewer reports on metastases to the lungs. Due to the low number of reported cases, prognosis and treatment of this neoplasm is not well defined.

High-grade myoepithelial carcinoma can show histologically undifferentiated/anaplastic features

High grade malignant tumors with a poorly-/un-differentiated morphology pose significant diagnostic challenges. Increasingly, the use of adjunct immunohistochemical and molecular tests to characterize and delineate the histopathologic phenotype of these tumors has become necessary, particularly in head and neck tumors. Recently, several entities with a poorly-/un-differentiated light microscopic morphology have been defined based on specific immunohistochemical and genetic characteristics. We herein describe two cases of high-grade myoepithelial carcinoma, one occurring in the submandibular gland and the other occurring in the left nasal cavity, both showing undifferentiated histological and anaplastic cytomorphological features. This led to very broad differential diagnostic considerations and the diagnosis was only established after extensive immunohistochemical studies. Molecular testing for HPV was negative in both cases. Gene fusion analysis using a targeted sequencing assay (Archer® FusionPlex® system) did not identify fusions involving PLAG1, HMGA2, EWSR1 or ALK genes in either case. The submandibular tumor showed an aggressive clinical course, with diffuse pulmonary metastases at presentation, whilst the nasal cavity tumor showed only localized disease. Awareness of a subcategory of high-grade myoepithelial carcinomas with undifferentiated light microscopical features is of significant importance in antibody selection for immunohistochemical investigation of poorly-/undifferentiated malignant tumors in the head and neck region. This histological variant of myoepithelial carcinoma adds to the growing list of differential diagnoses in this diagnostically complex and multifaceted field.

Clear cell myoepithelial carcinoma involving vestibule and alveolus: A rare case report with review of literature

Myoepithelial carcinomas (MCs) are difficult to distinguish from their benign counterpart due to diverse morphology. This neoplasm was introduced by Stromeyer et al. in 1975. They comprise of <2% of all salivary gland carcinomas involving most commonly major salivary glands and are characterized by differentiation of tumor cells into myoepithelial cells. The cells may present as epithelioid, plasmacytoid, spindle, clear, stellate and mixed type predominantly. Literature search revealed very few cases reported as clear cell variant of MC. Here, we report a case of clear cell MC involving buccal vestibule extending up to alveolus. The diagnosis was confirmed, and the patient was surgically treated.

Plasmacytoid Myoepithelioma of the Hard Palate: Case Report

Background

Myoepitheliomas are uncommon salivary gland neoplasms consisting entirely or predominantly of cells with myoepithelial phenotype. They commonly involve the parotid gland and the minor salivary glands of the palate.

Aim

A case of plasmacytoid myoepithelioma of the hard palate is described.

Case description and results

A 55-year-old woman presented to her oral surgeon with a tumor on the hard palate. Microscopic examination showed a well-circumscribed but non-encapsulated tumor, consisting mostly of plasmacytoid cells in a loose fibrovascular stroma. Neoplastic myoepithelial cells showed immunoreactivity for S-100 protein, CK AE1/AE3 (Figure 5b), GFAP, calponin, and CD138/Syndecan-1. Total excision of the tumor under local anesthesia was performed and no recurrence was noted 14 months after treatment.

Conclusions

Since plasmacytoid myoepithelioma is uncommon, minor salivary glands, its immunohistochemical features, management and prognosis should be further investigated.

Myoepithelial carcinoma of the vallecula: A case report and review of the literature

Myoepithelial carcinoma (MEC) of the vallecula is relatively rare, and there is no specific surgical guideline for resecting MEC in the vallecula. To the best of our knowledge, the current study reports the first case of MEC involving the vallecula of a 48-year-old female patient. In the present study, the lesion was correctly diagnosed as MEC and successfully managed using lateral pharyngotomy and by the construction of a sternohyoid myofascial flap. The patient was free of local recurrence or metastasis 18 months after surgery. The present study briefly reviews the current knowledge concerning the diagnosis and treatment of MECs in the head and neck area and offers suggestions for managing MEC in the vallecula. To conclude, MEC of the vallecula may be successfully managed by surgical treatment without evident post-surgery complications.

Prognostic Factors in Myoepithelial Carcinoma of the Major Salivary Glands

OBJECTIVES

(1) Identify all cases of myoepithelial carcinoma of the major salivary glands from the National Cancer Data Base (NCDB). (2) Analyze the effect of grade, stage, and regional nodal metastasis on survival in myoepithelial carcinoma of the major salivary glands.

STUDY DESIGN

Retrospective review of NCDB.

SETTING

Multicenter data pooled from 1998 to 2012 in the NCDB.

METHODS

We identified all reported cases of myoepithelial carcinomas of the major salivary glands from the United States from 1998 to 2012 in the NCDB. Clinical parameters were then examined and analyzed for predictors of survival.

RESULTS

A total of 473 cases of myoepithelial carcinoma were identified. Of the reported cases, 38.1% were low grade; 26.7%, intermediate grade; and 35.2%, high grade. When presenting stage was examined, 24.4% were stage I; 30.6%, stage II; 22.5%, stage III; 12.2%, stage IVa; 3.0%, stage IVb; and 4.1%, stage IVc. At presentation, 18.7% of patients had regional nodal disease, and 4.5% had distant metastases. The 3- and 5-year survival rates were 73% and 64%, respectively. The presence of nodal disease significantly reduced mean survival time versus those without (64 vs 108 months, P < .001), as did high-grade disease compared with low grade (67 vs 114 months, P < .001) and stage III/IV compared with stage I/II disease (61 vs 118 months, P < .001).

CONCLUSIONS

The presence of regional nodal disease, high-grade disease, and advanced stage are predictors of lower survival in myoepithelial carcinoma. Further studies based on types of treatment are warranted.