Myoepithelial carcinoma of the salivary glands: a clinicopathologic study of 25 patients

Histological and imaging features of myoepithelial carcinoma of the bone and soft tissue

OBJECTIVE

To depict histological and imaging features of myoepithelial carcinoma of the bone and soft tissue.

MATERIALS AND METHODS

We retrospectively examined histological features in 22 patients with myoepithelial carcinoma of the bone (4 patients) and soft tissue (18 patients) at a single institution. Imaging analysis of 15 patients (bone, 3 patients; soft tissue, 12 patients;) with preoperative images involved classifying lytic bone lesions via the modified Lodwick-Madewell classification; the growth patterns of soft tissue lesions were classified as well-defined, focally invasive, or diffusely invasive.

RESULTS

Local recurrence occurred in eight out of 22 patients (36.3%). Four of 22 patients (18.2%) had metastasis at presentation, whereas 11 of 22 patients (50.0%) had distant metastasis during follow-up. Severe cytological pleomorphism was observed in 14 of 22 patients (63.6%), and 10 of 22 tumors (45.5%) showed ≥ 10 mitoses/10 high-power fields. Vascular invasion was observed in 10 of 22 patients (45.5%). Extracapsular/extraskeletal infiltration into the surrounding tissues was assessed in 20 patients, with 14 of them (70%) showing infiltration beyond the tumor border. Regarding imaging of bone lesions, two patients had Ludwick type IIIB, whereas one patient had type II. The growth pattern of soft tissue lesions was well-defined in two patients (16.7%), focally invasive in seven patients (58.3%), and diffusely invasive in three (25.0%) out of 12 patients.

CONCLUSION

Myoepithelial carcinoma of the bone and soft tissue presents high risk of local recurrence and distant metastasis. Histological and imaging features might be important to understand the aggressive behavior of the tumor.

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.

Myoepithelioma- An Uncommon Parotid Tumour in An Adolescent

Myoepitheliomas are uncommon neoplasms of major and minor salivary glands. These tumours are encapsulated and slow growing in nature and are benign in majority of the cases. The mean age of presentation is 40 years and this entity is rarely reported in younger age groups. Here, we seek to report a rare case of a 10-year-old patient who presented with a swelling below the right ear. Clinical and radiological evaluation revealed a mass in the parotid gland. This patient was treated with a superficial parotidectomy and subsequent histopathological examination revealed it to be a myoepithelioma.

Malignant myoepithelioma of the external auditory canal - a rare case report with literature review and clinical importance of foramen of Huschke

BACKGROUND

A malignant myoepithelioma is a rare tumor, mostly arising from the salivary glands. Myoepitheliomas of the ear have rarely been reported. The manuscript reports myoepithelial carcinoma of the external auditory canal (EAC) spreading to the infratemporal fossa. A clinician must be aware of anatomical variation of the bony EAC wall, such as the foramen of Huschke. This rare defect may be a pathway for spreading pathologies between these two anatomical regions.

CASE REPORT

We present a case of osteoma-like stenosis of the EAC, which turned out to be an extremely rare malignant tumor. The preoperative MRI and PET/CT revealed that two parts of the tumor communicated through a defect in the antero-inferior portion of the bony ear canal. No distant metastases were detected. Subsequently, the tumor was resected from the ear canal and the infratemporal fossa en bloc. Perioperatively the defect in the EAC wall was suspected of the foramen of Huschke. After the surgery, the older scans of the patient from the past showed no presence of a congenital EAC wall defect. Therefore, the authors concluded that the tumor aggressively grew through the bone due to its biological nature.

CONCLUSION

Malignant myoepithelioma of the external auditory canal is an extremely rare condition and could be misdiagnosed as other benign lesions. In cases of suspicious lesions, it is advisable to do a probatory biopsy from the EAC. Surgery is the treatment of choice in malignant myoepitheliomas, and regular follow-ups are essential to monitor for recurrence or metastatic disease. Any mass located at the antero-inferior portion of the EAC wall warrants close evaluation due to its potential for expansion from the EAC.

Myoepithelial Carcinoma of Sinonasal Cavity: Peculiar Diagnosis, Conventional Treatment

Myoepithelial carcinoma is a morphologically diverse tumor which either arises de novo or from the malignant transformation of its benign counterpart i.e. myoepithelioma. These are relatively lesser known entities and are rarely found in head and neck region. Although rare, their first presentation is usually a painless growing mass as seen in our case presentation as well and are infamous for lymph node recurrence and distant metastasis. Due to their clinical presentation and varied morphology these become tedious to diagnose and pose difficulty for a surgeon when presented at a later date due to their effect on the adjacent vital structures. We report a case of myoepithelial carcinoma in head and neck region arising from the nasal cavity, it's mass effect on the adjacent vital organs and the diagnosis and treatment plan to render the patient free of this tumor, preservation of the vision and keeping the recurrence of the tumor at bay.

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.

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.

Myoepithelial carcinoma of the parotid gland with a novel CTCF::NCOA2 fusion

We describe a case of a myoepithelial carcinoma of the superficial parotid gland in a 46-year-old male harboring a novel CTCF::NCOA2 gene fusion. To our knowledge, this novel gene fusion has not been described previously in myoepithelial carcinoma. A 46-year-old male patient presented with a mass involving the superficial left parotid gland with extension into the external auditory canal (EAC) and erosion of the conchal cartilage. Histologically, the neoplasm was composed of uniform spindled, epithelioid/ovoid cells arranged in cords and nests within hyalinized to myxoid stroma. On immunohistochemistry (IHC), the tumor cells demonstrated patchy and variable staining for low molecular weight cytokeratin (CAM5.2), pan-cytokeratin (OSCAR), and S-100. Overall, the morphological and immunohistochemical attributes supported a locally aggressive tumor of myoepithelial differentiation consistent with myoepithelial carcinoma. Molecular analysis using a custom 115-gene gene panel by targeted RNA sequencing, showed an in-frame CTCF::NCOA2 fusion. In addition to reporting this novel fusion in myoepithelial carcinoma, we also discuss relevant differential diagnosis, and provide a brief review of NCOA2 gene function in both normal and neoplastic contexts.

Myoepithelial Carcinoma Arising in a Salivary Duct Cyst of the Parotid Gland: Case Presentation

Cystic lesions observed in parotid glands are relatively rare and comprise 2-5% of all parotid primaries. A salivary duct cyst (SDC) is a true cyst representing 10% of all salivary gland cysts. The risk of malignant transformation of SDC's epithelium is extremely rare. In the literature, only three cases of carcinoma ex SDC of the parotid gland are described. This report presents the first in the literature case of myoepithelial carcinoma (MECA) arising from a parotid SDC. A 75-year-old male patient was referred to the Department of Cranio-Maxillofacial Surgery of the Jagiellonian University in Cracow, Poland due to a cystic tumor arising from the right parotid gland. Superficial parotidectomy with facial nerve preservation was performed. Histological examination confirmed a rare case of MECA emerging from the SDC. The immunohistochemical profile of MECA ex SDC was presented. During 6 months of the follow-up, local recurrence or distant metastasis was not observed.

Abdominal myoepithelial carcinoma: A rare abdominal wall entity of an uncommon tumor

Introduction and importance

Case presentation

Clinical discussion

Conclusion

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Extra-salivary myoepithelial carcinoma is an extremely rare entity, may present as an abdominal mass.

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In contrast to their salivary-gland counterparts, most of them are malignant to begin with.

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Limited data is available for their management, hence such patients should be enrolled in clinical trials whenever available.

Oncocytic low-grade myoepithelial carcinoma ex pleomorphic adenoma - A rare case illustrating key learning points

BACKGROUND

Oncocytic myoepithelial carcinoma ex pleomorphic adenoma neoplastic is a rare neoplastic event and may not display overt malignant radiological features.

METHODS

Using routine histopathology and immunohistochemistry, we characterize a case of low-grade oncocytic carcinoma ex pleomorphic adenoma.

RESULTS

The tumor arose in the left parotid gland in a 59 year old female. Computed tomography (CT) imaging demonstrated a well-defined, lobulated, enhancing lesion with relative central stellate hypoenhancement. Histologically, the tumor displayed a multi-nodular, non-destructive, invasive pattern, low mitotic activity (one mitotic figure per 10 high power fields) and a small remnant focus of pleomorphic adenoma. The neoplastic cells showed significant expression of cytokeratin 5/6, S-100 protein, smooth muscle actin and p63.

CONCLUSION

Low-grade oncocytic carcinoma ex pleomorphic adenoma is a challenging histopathological diagnosis which can be established with use of immunohistochemistry, generous tumor sampling and recognition of the multi-nodular, non-destructive, pattern of invasion. In the absence of clear-cut tumor encroachment into external structures, its malignant nature may not be easily identified on pre-operative imaging.

Clear Cell Neoplasms of Salivary Glands: A Diagnostic Challenge

This review focuses on the heterogenous group of clear cell neoplasms of salivary glands and attempts to identify major differential diagnostic features. Within the head and neck region, clear cells are found most commonly in salivary gland tumors, but may also be seen in tumors of squamous or odontogenic epithelial origin, primary or metastatic carcinomas, benign or malignant melanocytic lesions, or benign or malignant mesenchymal tumors. Clear cells occur fairly commonly among a wide variety of salivary gland neoplasms, but mostly they constitute only a minor component of the tumor cell population. Clear cells represent a major diagnostic feature in two salivary gland neoplasms, epithelial-myoepithelial carcinoma and hyalinizing clear cell carcinoma. In addition, salivary gland neoplasms composed predominantly of clear cells could also include clear cell variants of other salivary neoplasms, such as mucoepidermoid carcinoma and myoepithelial carcinoma, but their tumor type-specific histologic features may only be available in limited nonclear cell areas of the tumor. Diagnosing predominantly clear cell salivary gland tumors is difficult because the immunoprofiles and morphologic features may overlap and the same tumor entity may also have a wide range of other histologic presentations. Many salivary gland tumors are characterized by tumor type-specific genomic alterations, particularly gene fusions of the ETV6 gene in secretory carcinoma, the MYB and MYBL1 genes in adenoid cystic carcinoma, the MAML2 gene in mucoepidermoid carcinoma, the EWSR1 gene in hyalinizing clear cell carcinoma, and others. Thus, along with conventional histopathologic examination and immunoprofiling, molecular and genetic tests may be important in the diagnosis of salivary gland clear cell tumors by demonstrating genetic alterations specific to them.

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 of soft tissue is a diagnostic challenge on fine-needle aspiration: Case report and review of literature

Myoepithelial carcinoma (MEC) of soft tissue, also known as malignant myoepithelial tumor, is an uncommon malignancy. Cytologic diagnosis of this entity is challenging due to its rarity and heterogeneous morphology. We report a case of MEC in a 22-year-old man, who presented with a 6.5 cm soft tissue mass on his right distal forearm that has been enlarging over the past 3 months. Ultrasound-guided fine-needle aspiration (FNA) revealed abundant isolated neoplastic cells ranging from spindled cells to epithelioid and plasmacytoid morphology in a myxoid background. These cells showed moderate cytologic atypia characterized by high-nuclear/cytoplasmic ratio, irregular nuclear contours, and prominent nucleoli. The cytoplasm varied from dense to vacuolated and occasionally rhabdoid with intracytoplasmic inclusions. Scattered bi- and multinucleated cells were identified. A diagnosis of high-grade malignancy was made with the differential diagnosis including rhabdomyosarcoma and melanoma. A subsequent core biopsy of the tumor showed immunoreactivity for pan-cytokeratins, calponin, p63, and smooth muscle actin. INI-1 was lost. SOX-10 and Melan-A were negative. Molecular studies showed loss of SMARCB1 (INI-1) and CDKN2A. Gene fusion studies did not detect any fusion. A diagnosis of soft tissue MEC was made which is a challenge on FNA due to several cytologic mimickers including rhabdomyosarcoma, epithelioid sarcoma, extrarenal rhabdoid tumor, extra-axial chordoma and melanoma. Recognition of the biphasic cell population in a myxoid background and a battery of immunohistochemical stains are crucial for accurate diagnosis.

Prognostic analysis and establishment of a nomogram in patients with myoepithelial carcinoma of the salivary gland: A population-based study

BACKGROUND

Currently, the clinicopathological characteristics and prognosis of myoepithelial carcinoma of salivary gland (MC-SG) have not been defined well. The present study aimed to describe the clinicopathological characteristics and prognosis of MC-SG patients.

METHODS

The Surveillance, Epidemiology, and End Results database was searched for all patients diagnosed with MC-SG between 1991 and 2016. The Kaplan-Meier method and log-rank tests were used to evaluate the survival. Univariate and multivariate Cox regression analysis were used to identify prognostic biomarkers for overall survival (OS) and disease-specific survival (DSS). Furthermore, a prognostic nomogram was established, and its predictive accuracy and discriminative ability were determined using the concordance index (C-index).

RESULTS

In total, 245 patients diagnosed with MC-SG were identified. The median OS was 152.0 months, with 3-, 5-, and 10-year survival rates of 79.8%, 69.2%, and 50.3%. The 3-, 5-, and 10-year DSS rates were 82.5%, 77.1%, and 61.9%, respectively. Regarding the treatment regimen, most patients (92.2%) underwent surgery, and 103 patients (42.4%) received postoperative radiotherapy. Surgery could significantly prolong OS and DSS (p < .05), but postoperative radiotherapy did not significantly prolong OS and DSS when compared with individuals receiving surgery alone (p > .05). Multivariate Cox analysis revealed that T category (T4), lymph node metastasis (N2), distant metastasis (M1), and poor differentiation were independent unfavorable prognostic factors for OS and DSS. Older age (>62 years) was also independently associated with OS. In addition, the C-index for the established OS- and DSS-specific nomogram was 0.80 (95% CI: 0.72-0.88) and 0.82 (95% CI: 0.73-0.90).

CONCLUSION

Age, tumor invasion, metastases, and pathological grade were independently associated with prognosis of MC-SG patients, and the prognostic nomogram of this rare disease was established.

High Grade Myoepithelial Carcinoma of Maxillary Sinus with Extensive Rhabdoid Differentiation and INI-1 Loss: Expanding the Histopathological Spectrum of Sinonasal Carcinoma

Myoepithelial carcinoma (MEC) of salivary gland is an uncommon tumor with no specific age or sex predilection. Most of the cases (~90%) arise in parotid and submandibular glands followed by palate. MEC of maxillary sinus is rare. We describe an extremely rare case of high grade MEC with rhabdoid differentiation and INI-1 loss involving maxillary sinus of an elderly male.

Proliferative Activity of Myoepithelial Cells in of Mucoepidermoid Carcinoma

AIM: The aim of the study is to investigate the role of myoepithelial cells in the pathogenesis of mucoepidermoid carcinoma (MEC) using the double immunohistochemical staining; α _smooth muscle actin (_α-SMA)as specific marker for the myoepithelial cell differentiation and proliferative cell nuclear antigen (PCNA) as a marker for proliferative activity of myoepithelial cells. MATERIAL AND METHODS: Retrospective study of twenty salivary gland specimens (ten MEC and ten normal salivary glands) were studied using double immunohistochemical labeling for α _smooth muscle actin α-SMA) and proliferative cell nuclear antigen (PCNA). The SPSS statistical package was used for data analysis (IBM SPSS Statistics for Windows, Version 20.0, Released 2011, IBM Corp, and Armonk, NY, USA). RESULTS: In mucoepidermoid carcinomas, no positivity of α-SMA was seen in neoplastic cells (Frequent test), and it was just observed in the stroma of tumor, in the walls of blood vessels whereas, PCNA was positive, especially in high-grade tumors. In contrast, in normal salivary glands, the proliferating myoepithelial cells are stained by both α-SMA and PCNA. CONCLUSIONS: We believe that the myoepithelial cells have no a role in the development of mucoepidermoid carcinoma.

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.

Primary high-grade myoepithelial carcinoma of the lung: A study of three cases illustrating frequent SMARCB1-deficiency and review of the literature

Primary myoepithelial carcinoma of the lung is exceptionally rare and, hence, remained poorly characterized. We present 3 tumors affecting 2 males and 1 female aged 60 to 84 years. Tumor size ranged from 4 to 10 cm. All presented as well circumscribed non-encapsulated peripheral solitary masses. One patient died postoperatively. The other two were lost to follow-up. Histologically, all tumors were high-grade with predominance of myxoid/chordoid (2) and rhabdoid (1) pattern. Immunohistochemistry (IHC) showed reactivity with vimentin, pankeratin, EMA and smooth muscle actin. Two tumors were SMARCB1-deficient (one with additional loss of SMARCA2 and PBRM1). RNA sequencing revealed no gene fusions. Review of reported cases (total: 16) showed that pulmonary myoepithelial carcinoma affects both sexes equally at a median age of 60 years (24-84), presents predominantly as peripheral masses (69%) in the lower lobes (66%) of smokers (70%) with a median size of 6 cm (1.5-13), and originates as high-grade de novo carcinoma. Forty percent of patients died of disease at a median of 12.5 months (0 to 62). Only 40% of patients were disease free at last follow-up (median, 9.5 months). Prominent lobulation and myxoid stroma were frequent histological features. Most tumors displayed variable combinations of epithelioid, spindle, plasmacytoid, clear, ovoid or round cells. Three of 6 tumors subjected to different RNA panels showed EWSR1 rearrangements (fused to PBX1, ZNF444 or to unknown partner). Two of 3 tumors lacking gene fusions were SMARCB1-deficient (both showed secondary EWSR1 FISH abnormalities due to 22q deletion). Primary pulmonary myoepithelial carcinoma is a rare aggressive malignancy that recapitulates its soft tissue and salivary counterpart. Exclusion of metastasis from other primaries is mandatory and can only be achieved by detailed clinical history and imaging.

Rare Diseases of the Salivary Glands and of Facial Nerve

Salivary gland diseases are rare. In the European Union (EU) a disease is considered to be rare if not more than 5 of 10,000 people are affected by it. According to estimates in Germany are about 4 million people with a rare disease. In the EU are about 30 million people with rare diseases [1]. In the present work most of the described diseases of salivary glands and of the facial nerve fall in this category. They form a very heterogeneous group whose treatment takes place mainly in specialized centers. Still, it is essential for the otolaryngologist to identify and to diagnose these diseases in order to initiate the right therapeutic steps. The work is a compilation of innate andacquired rare salivary gland disorders and of rare facial nerve disorders. The etiologies of inflammatory diseases, autoimmune disorders and tumors are taken into account. For the individual topics, the current literature, if available, was evaluated and turned into summarized facts. In this context the development of new processes, diagnostics, imaging and therapy are considered. Genetic backgrounds of salivary gland tumors and the trends in the treatment of tumorous lesions of the facial nerve are picked up. Furthermore, also rare diseases of the salivary glands in childhood are described. Some of them can occur in adults as well, but differ in frequency and symptoms. Due to the rarity of these diseases, it is recommended to tread these in centers with special expertise for it. Finally, the difficulties of initiation of studies and the problems of establishing disease registries concerning salivary gland disorders are discussed. This is very relevant because these pathologies are comparatively seldom.

Nasopharyngeal carcinoma ex-pleomorphic adenoma (noninvasive): A report of a rare case

Pleomorphic adenoma (PA) is the most common type of benign tumors of minor salivary glands. A carcinoma ex-pleomorphic adenoma (CXPA) is a malignant epithelial neoplasm originating from either a primary or recurrent benign PA. The nasopharynx is an extremely uncommon location for this tumor. A 32-year-old male had complaints of nasal blockage. In noncontrast computed tomography, a soft-tissue mass was present in the nasopharynx. Histopathological and immunohistochemical examination of the endoscopically excised mass revealed features of CXPA, noninvasive in nature. Careful histopathological examination is the key to identify this uncommon entity. To the best of our knowledge, <20 cases have been published so far.

Myoepithelial Carcinoma

Myoepithelial carcinoma (MECA) may overlap histologically with other salivary gland neoplasms, especially pleomorphic adenoma. MECA is characterized by cellular, uniform growth of myoepithelial cells and multinodular expansile invasive pattern with zonal cellular distribution. It may arise de novo or in association with pleomorphic adenoma (myoepithelial carcinoma ex pleomorphic adenoma). By immunohistochemistry, MECA is positive for cytokeratins and at least one of the myoepithelial markers, including S100. PLAG1 fusion is the most common genetic alteration. Carcinoma ex pleomorphic adenoma and necrosis correlate with worse clinical outcome in MECA, and necrosis can be used to stratify MECA as high grade.

Myoepithelial Carcinoma Ex Pleomorphic Adenoma of the Maxillary Sinus: A Case Report and Review of Literature

Myoepithelial carcinoma ex pleomorphic adenoma is defined as a malignant epithelial neoplasm arising from a primary or recurrent benign pleomorphic adenoma. This type of tumor comprises 3.6% of all salivary gland tumors and 12% of malignant ones. Clinically, it most commonly presents as a firm mass in the parotid gland. The development of this neoplasm in the sinonasal and nasopharyngeal regions is extremely rare and only few cases are reported in the literature. The prognosis of myoepithelial carcinoma is variable. Marked cellular pleomorphism, high mitotic rate, and high proliferative activity correspond to a poor prognosis. In this article, the authors report the histopathological features of a clinical case of a 64-years-old patient with a large median maxillary neoplasm diagnosed as myoepithelial carcinoma/ex-pleomorphic adenoma. The tumor was resected and subjected to secondary reconstruction using a revascularized free fibula flap. The myoepithelial derivation of neoplastic cells was demonstrated by immunohistochemical positivity for S-100 protein (strong and diffuse), cytokeratin 14 (strong and diffuse), and GFAP (focal).

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.

Two cases of rare thyroid malignancy-case report

We report 2 cases of rare thyroid malignancy: angiosarcoma and myoepithelial carcinoma (MC). Thyroid angiosarcomas (TAS) is extremely rare and comprises less than 1% of primary thyroid cancer worldwide. MC usually presents as a slow-growing painless mass arising in the salivary glands. It has not been reported in the thyroid gland. The first case describes a 59-year-old patient who was admitted to hospital with the discovery of thyroid nodule for 1 month. The tumor thrombus was found in the left internal jugular vein and superior thyroid artery during the operation. Diagnosis of angiosarcoma of the thyroid was based on positive endothelial markers such as thrombomodulin and CD31 after total thyroidectomy. The left internal jugular vein, left recurrent laryngeal nerve and anterior cervical banding muscle were invaded by thyroid tumor. No lymph node metastasis was observed. The patient died after 4 years. The second case describes a 55-year-old woman who presented with the discovery of thyroid nodule for 1 month. Right thyroid lobectomy and right neck lymph node functional dissection were carried out. The results from postoperative pathology revealed that papillary carcinoma in right lobe of thyroid and MC next to thyroid were found. Besides, the metastasis of MC was observed at right II-IV level and right VI level. Five years later, the patient was re-admitted to hospital, primarily due to the discovery of anterior cervical tumor for one year. Then, she underwent left thyroid lobectomy and right tumor resection. Postoperative routine pathology showed recurrent MC in the right thyroid. After surgery and radiotherapy, the patient was followed up for 2 years. Angiosarcoma and myoepithelioma should be kept in mind in diagnosis of thyroid malignant tumor.

Myoepithelial Carcinoma Arising in a Plasmacytoid Myoepithelioma of the Parotid Gland Synchronized with Melanoma: A Case Report and Review of the Literature

Myoepithelial carcinoma, also known as malignant myoepithelioma, is considered an extremely rare (0.45-1%) malignant salivary gland neoplasm. Approximately 100 cases have been reported in the English-language literature on myoepithelial carcinoma. The majority of the myoepitheliomas described in the literature have been benign, and the malignant counterpart is considered rare (<1%). Such a tumor may appear de novo or rarely develop from a preexisting pleomorphic adenoma (<20%), and in exceedingly rare cases (<0.5%), it has arisen from a benign myoepithelioma (i.e., plasmacytoid myoepithelioma). To our knowledge, no case of myoepithelial carcinoma of the parotid gland arising in a plasmacytoid myoepithelioma synchronized with melanoma has been reported to date. The treatment of myoepithelial carcinoma has been mainly surgical, including wide excision with free margins, with or without nodal dissection. The roles of chemotherapy and radiotherapy have not yet been established. We report a case of myoepithelial carcinoma of the parotid gland arising in a plasmacytoid myoepithelioma synchronized with melanoma in a 40-year-old woman. In our case, a complete response was achieved with surgery followed by adjuvant chemotherapy based on carboplatin and paclitaxel concurrent with radiotherapy.

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.

A first case report of clinical response to targeted therapy in a patient with primary myoepithelial carcinoma of the lung harboring EGFR exon 19 deletion

BACKGROUND

Primary myoepithelial carcinoma of the lung is a rare subtype in lung cancer. Comprehensive molecular profiling of myoepithelial carcinoma of the lung is absent, neither was clinical evidence of targeted therapy available for this disease. Therefore, the optimal treatment regimen of this tumor needs to be established.

CASE PRESENTATION

Here we present a case of a 68-year-old patient with stage IVB primary myoepithelial carcinoma of the lung who harbored EGFR exon 19 deletion and KRAS mutation and underwent icotinib targeted therapy, achieving partial response (PR) with progression free survival (PFS) of 3 months.

CONCLUSION

To our knowledge, this study describes the first documented case of primary myoepithelial carcinoma lung cancer patient harboring EGFR exon 19 deletion and KRAS mutation, and showed clinical efficacy of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKI) treatment in this patient.

Pulmonary Myoepithelial Tumors With Exuberant Reactive Pneumocytes: Proposed Reclassification of So-called Pneumocytic Adenomyoepithelioma

Pneumocytic adenomyoepithelioma (PAM) was first described in 2007 and was included in the 2015 World Health Organization Classification of lung tumors as a variant of epithelial-myoepithelial tumor. This rare pulmonary neoplasm was reported to show both myoepithelial and duct-like components, with the latter exhibiting pneumocytic differentiation with TTF-1 expression. We present an index case and 6 additional retrospectively identified cases of pulmonary tumors with prototypical features of PAM. However, with additional clinicoradiologic, histologic, immunohistochemical and cytogenetic data, we were able to reclassify them as myoepithelial neoplasms-both primary and metastatic-with entrapped exuberantly hyperplastic alveolar structures lined by TTF-1 pneumocytes. We reviewed the available literature related to PAM and myoepithelial tumors. Our cases suggest that the entity referred to as PAM represents interstitial growth of myoepithelial neoplasms enticing marked proliferation of entrapped pneumocytes rather than a distinct biphasic neoplasm with pneumocytic differentiation.

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.

Metachronous Pancreatic and Thyroid Metastases from Primary Soft-Tissue Myoepithelioma in the Clavicular Region: A Case Report of a Long-Term Survivor

Patient: Male, 69-year-old

Final Diagnosis: Metachronous pancreatic and thyroid metastases from primary soft tissue myoepithelioma

Symptoms: None

Medication:—

Clinical Procedure: Surgery

Specialty: Surgery

[Immunophenotyping of lung tumors : An update]

The WHO Classification of Lung Tumors (2015) established the use of immunohistochemical stainings for resection specimens, however, detailed recommendations had been missing. Now, an international expert panel has summarized key questions for daily routine practice and provided recommendations to assist the community in the appropriate use of immunohistochemistry in this context. This article provides an overview of the most important aspects.

Analysis of the Clinical Relevance of Histological Classification of Benign Epithelial Salivary Gland Tumours

INTRODUCTION

A vast increase in knowledge of numerous aspects of malignant salivary gland tumours has emerged during the last decade and, for several reasons, this has not been the case in benign epithelial salivary gland tumours. We have performed a literature review to investigate whether an accurate histological diagnosis of the 11 different types of benign epithelial salivary gland tumours is correlated to any differences in their clinical behaviour.

METHODS

A search was performed for histological classifications, recurrence rates and risks for malignant transformation, treatment modalities, and prognosis of these tumours. The search was performed primarily through PubMed, Google Scholar, and all versions of WHO classifications since 1972, as well as numerous textbooks on salivary gland tumours/head and neck/pathology/oncology. A large number of archival salivary tumours were also reviewed histologically.

RESULTS

Pleomorphic adenomas carry a considerable risk (5-15%) for malignant transformation but, albeit to a much lesser degree, so do basal cell adenomas and Warthin tumours, while the other eight types virtually never develop into malignancy. Pleomorphic adenoma has a rather high risk for recurrence while recurrence occurs only occasionally in sialadenoma papilliferum, oncocytoma, canalicular adenoma, myoepithelioma and the membranous type of basal cell adenoma. Papillomas, lymphadenoma, sebaceous adenoma, cystadenoma, basal cell adenoma (solid, trabecular and tubular subtypes) very rarely, if ever, recur.

CONCLUSIONS

A correct histopathological diagnosis of these tumours is necessary due to (1) preventing confusion with malignant salivary gland tumours; (2) only one (pleomorphic adenoma) has a considerable risk for malignant transformation, but all four histological types of basal cell adenoma can occasionally develop into malignancy, as does Warthin tumour; (3) sialadenoma papilliferum, oncocytoma, canalicular adenoma, myoepithelioma and Warthin tumour only occasionally recur; while (4) intraductal and inverted papilloma, lymphadenoma, sebaceous adenoma, cystadenoma, basal cell adenoma (apart from the membranous type) virtually never recur. No biomarker was found to be relevant for predicting recurrence or potential malignant development. Guidelines for appropriate treatment strategies are given.

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.

Clear cell, giant myoepithelioma of tongue base: a diagnostic and surgical challenge

Clear cell variant is a rare histological type of myoepithelioma seen in parotid and soft palate. This article describes clear cell variant of myoepithelioma in the tongue base, which has not been reported in the literature so far. A 34-year-old man presented with dysphagia and foreign body sensation of throat. Video laryngostroboscopy using a 70° rigid telescope showed a smooth globular mass in the oropharynx arising from the tongue base. Based on clinical and radiological findings, the lesion was considered as benign. Fine needle aspiration cytology was not attempted fearing risk of bleeding, aspiration and airway compromise. Hence, an excisional biopsy followed by definitive histopathological examination without frozen section was planned. The patient underwent coblator-assisted excision and subsequently sent for histopathological analysis. There were cuboidal cell nests with abundant clear cytoplasm which stained positive for p63 by immunohistochemistry. This helped in establishing the diagnosis of clear cell myoepithelioma.

Best Practices Recommendations for Diagnostic Immunohistochemistry in Lung Cancer

Since the 2015 WHO classification was introduced into clinical practice, immunohistochemistry (IHC) has figured prominently in lung cancer diagnosis. In addition to distinction of small cell versus non-small cell carcinoma, patients' treatment of choice is directly linked to histologic subtypes of non-small cell carcinoma, which pertains to IHC results, particularly for poorly differentiated tumors. The use of IHC has improved diagnostic accuracy in the classification of lung carcinoma, but the interpretation of IHC results remains challenging in some instances. Also, pathologists must be aware of many interpretation pitfalls, and the use of IHC should be efficient to spare the tissue for molecular testing. The International Association for the Study of Lung Cancer Pathology Committee received questions on practical application and interpretation of IHC in lung cancer diagnosis. After discussions in several International Association for the Study of Lung Cancer Pathology Committee meetings, the issues and caveats were summarized in terms of 11 key questions covering common and important diagnostic situations in a daily clinical practice with some relevant challenging queries. The questions cover topics such as the best IHC markers for distinguishing NSCLC subtypes, differences in thyroid transcription factor 1 clones, and the utility of IHC in diagnosing uncommon subtypes of lung cancer and distinguishing primary from metastatic tumors. This article provides answers and explanations for the key questions about the use of IHC in diagnosis of lung carcinoma, representing viewpoints of experts in thoracic pathology that should assist the community in the appropriate use of IHC in diagnostic pathology.

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.