Epithelial-myoepithelial carcinoma of the lung: a case report

Evolving Diagnostic Approach of Pulmonary Salivary Gland-type Tumors

Pulmonary salivary gland-type, although bear resemblance to their salivary gland counterparts, present a diagnostic challenge due to their rarity. Clinical features overlap with lung carcinoma; however, management strategies and outcomes are distinct. Onus falls on the pathologist to avoid misinterpretation of small biopsies especially in young, nonsmokers with slow growing or circumscribed endobronchial growths. A combination of cytokeratin, myoepithelial immunohistochemical markers, and identification of signature molecular alteration is invaluable in differentiation from lung cancers and subtyping the pulmonary salivary gland-type tumor.

Rare but clinically important salivary gland-type tumor of the lung: A review

Salivary gland-type tumor (SGT) of the lung, which arises from the bronchial glands of the tracheobronchial tree, was first recognized in the 1950s. SGT represents less than 1% of all lung tumors and is generally reported to have a good prognosis. Mucoepidermoid carcinoma (MEC) and adenoid cystic carcinoma (ACC) are the two most common subtypes, comprising more than 90% of all SGTs. The reported 5-year survival rate of patients with SGT is 63.4%. Because this type of tumor develops in major bronchi, patients with SGT commonly present with symptoms of bronchial obstruction, including dyspnea, shortness of breath, wheezing, and coughing; thus, the tumor is usually identified at an early stage. Most patients are treated by lobectomy and pneumonectomy, but bronchoplasty or tracheoplasty is often needed to preserve respiratory function. Lymphadenectomy in the surgical resection of SGT is recommended, given that clinical benefit from lymphadenectomy has been reported in patients with MEC. For advanced tumors, appropriate therapy should be considered according to the subtype because of the varying clinicopathologic features. MEC, but not ACC, is less likely to be treated with radiation therapy because of its low response rate. Although previous researchers have learned much from studying SGT over the years, the diagnosis and treatment of SGT remains a complex and challenging problem for thoracic surgeons. In this article, we review the diagnosis, prognosis, and treatment (surgery, chemotherapy, and radiotherapy) of SGT, mainly focusing on MEC and ACC. We also summarize reports of adjuvant and definitive radiation therapy for ACC in the literature.

Recent developments in the pathology of primary pulmonary salivary gland-type tumours

Primary pulmonary salivary gland-type tumours are rare neoplasms that are thought to arise from seromucinous glands that are located in the submucosa of large airways. These neoplasms have clinical and pathologic features that are distinct from other pulmonary neoplasms. The majority of primary pulmonary salivary gland-type tumours are malignant, with the most common entities being mucoepidermoid carcinoma, adenoid cystic carcinoma, and epithelial-myoepithelial carcinoma. Less commonly seen are myoepithelial carcinoma, hyalinizing clear cell carcinoma, acinic cell carcinoma, secretory carcinoma, salivary duct carcinoma, intraductal carcinoma, and polymorphous adenocarcinoma. Benign salivary gland-type tumours of the lung include pleomorphic adenoma and sialadenoma papilliferum. Morphologic, immunophenotypic, and molecular features of these neoplasms are largely similar to salivary gland tumours elsewhere, and therefore the exclusion of metastatic disease requires clinical and radiologic correlation. However, the differential diagnostic considerations are different in the lung. The distinction of salivary gland-type tumours from their histologic mimics is important for both prognostication and treatment decisions. Overall, salivary gland type-tumours tend to have a more favourable outcome than other pulmonary carcinomas, although high-grade variants exist for many of these tumour types. Recent advances in our understanding of the spectrum of salivary gland-type tumours reported in the lung and their diversity of molecular and immunohistochemical features have helped to refine the classification of these tumours and have highlighted a few differences between salivary gland-type tumours of the lung and those primary to other sites.

Pulmonary Epithelial-Myoepithelial Carcinoma

Pulmonary epithelial-myoepithelial carcinoma (P-EMC) is an exceptionally rare subtype of salivary gland lung tumor originating from tracheobronchial glands. P-EMC is a biphasic tumor consisting of an inner layer of epithelial cells and an outer layer of spindle-shaped, clear-cell-like myoepithelial cells. Bronchial obstruction symptom is the main clinical characteristic for P-EMC. Because its clinical and imaging characteristics are highly similar to other types of non-small-cell lung cancer (NSCLC), it is easy to cause missed diagnosis and misdiagnosis. The diagnosis is mainly based on the pathology and immunohistochemistry with an inner layer of epithelial cells immunoreactive for cytokeratin and an outside layer of myoepithelial cells immunoreactive for S100 protein (S-100) and smooth muscle actin (SMA). Therefore, positive for cytokeratin, S-100 and SMA can assist in the diagnosis. Although in general, P-EMC is a low-grade malignant neoplasm, it may occasionally recur and metastasize. The optimal method for P-EMC treatment has not been established, and surgical resection is still the main clinical method. Radiotherapy and chemotherapy have been shown not sensitive for P-EMC treatment, whereas targeted therapy and immunotherapy have not evaluated in clinical practice. This review focuses on the pathological characteristics, molecular characteristics, diagnosis, treatment, and prognosis of P-EMC.

Epithelial–Myoepithelial Carcinoma of the Esophagus: A Case Report

Epithelial–myoepithelial carcinoma (EMC) of the esophagus is a rare biphasic tumor with low malignant potential, which has not previously been reported in the published literature. The present study describes the case of an asymptomatic, 53-year-old male who presented with EMC in the esophagus during a gastroscopic examination. Esophageal computed tomography (CT) showed thickening of the wall of the lower esophagus with a thickness of about 0.7 cm, and an enhanced scan showed uneven enhancement of the thickened esophageal wall. Thoracoscopic esophagectomy was performed because the tumor was malignant. Histopathology revealed that the tumor was characterized by a biphasic architecture consisting of cuboidal ductal cells and myoepithelial cells. The patient’s postoperative recovery was eventful, an anastomotic fistula occurred, and the patient was discharged from the hospital after 84 days. One year postsurgery, the patient remained in good health, with no evidence of metastasis and recurrence.

Pulmonary epithelial-myoepithelial carcinoma (P-EMC) with focal high grade transformation: Molecular and cytologic findings

BACKGROUND

Pulmonary epithelial-myoepithelial carcinoma (P-EMC) is a rare type of salivary gland tumor of the lung. Diagnosis from preoperative biopsies or fine needle aspiration (FNA) cytology specimens is difficult given the rarity of the tumor and overlapping cytomorphology with other entities. These tumors generally have a good prognosis, however prior reports of recurrence and metastasis to lymph nodes have been reported. Further, little is known about the malignant potential of high grade transformation. The molecular characteristics of this entity are unknown, with only a few case reports commenting on molecular findings. Here, we report a case of P-EMC with focal high grade transformation. We present its diagnostic pitfalls on cytology specimens, surgical pathology, immunohistochemistry, and molecular findings.

CASE PRESENTATION

A 72 year old female presented with an incidentally detected lung mass. A chest computed tomography (CT) demonstrated a left hilar mass measuring 4.1 cm with endobronchial extension into the left upper lobe. On the initial endobronchial core needle biopsy and cytology FNA, the tumor was misinterpreted as squamous cell carcinoma. The patient subsequently underwent a left pneumonectomy along with mediastinal lymph node dissection. Final surgical pathology of the resection specimen indicated a P-EMC with focal high grade transformation. The patient is disease-free 1 year post-surgery.

CONCLUSIONS

Due to the rarity of P-EMC, insufficient sampling and histologic heterogeneity, diagnosis of P-EMC on preoperative core needle biopsy or FNA specimen is difficult. Herein, we present a rare case of P-EMC, with a pre-operative FNA cytology specimen that consisted of tumor cells with dense cytoplasm and moderate cytologic atypia, strong positive staining pattern of p40, that was misdiagnosed as squamous cell carcinoma. Follow up surgical resection showed P-EMC with focal high grade transformation. Salivary gland EMCs with high grade transformation have previously been reported to have a worse prognosis, however, little is known about the malignant potential in the lung. Next generation sequencing (NGS) using a 397-gene solid tumor panel identified variants in DNMT3A, APC, STAT3 in both low and high grade components, while KDM5C was present only in the high grade transformation.

Salivary Gland-type Tumors of the Lung

CONTEXT.—

Salivary gland-type tumors (SGTs) of the lung represent a distinct group of lung neoplasms. Pulmonary SGTs often pose diagnostic challenges, especially in small biopsy and cytology samples because of limited sample volume and overlapping morphology among pulmonary SGTs, metastatic SGTs of head and neck origin, and other lung tumors.

OBJECTIVE.—

To identify the clinical characteristics, histomorphology, immunophenotypic features, and molecular alterations that are crucial for the diagnosis and differential diagnosis of pulmonary SGTs, especially in small biopsy and cytology specimens.

DATA SOURCES.—

Literature review and authors' personal practice experience.

CONCLUSIONS.—

An accurate diagnosis of pulmonary SGTs can be achieved by careful evaluation of clinical findings and histomorphology in conjunction with immunohistochemical studies and molecular analysis.

Robotic Resection of Pulmonary Epithelial Myoepithelial Carcinoma: A Case Report

Background  Pulmonary epithelial–myoepithelial carcinoma (P-EMC) is an extremely rare, well-differentiated, and malignant neoplasm originating from submucosal bronchial glands in the lung. EMCs arise mainly in the salivary glands.

Case Description  This case represents an asymptomatic 78-year-old male with a remote 75-pack-year history of smoking who presents with a solitary endobronchial lesion, which is suggestive of a primary lung EMC, detected on annual screening chest computed tomography (CT) scan.

Conclusion  A recent review of literature reveals less than 50 documented cases of the pulmonary subtype of this tumor worldwide. We are reporting a unique case of robot-assisted pulmonary lobectomy for a P-EMC.

Recent updates in salivary gland tumors of the lung

Salivary gland tumors are uncommon primary lesions in the lung. Their morphologic, immunophenotypic, and molecular characteristics resemble those of their counterparts in the head and neck or elsewhere. Most common primary pulmonary salivary gland tumors include mucoepidermoid carcinoma, adenoid cystic carcinoma, and epithelial-myoepithelial carcinoma. The study of these neoplasms is hampered by their paucity. Therefore, studies are in general small or restricted to individual cases. Despite this challenge recent advances have been made specifically at the molecular level. Molecular alterations such as MAML2 rearrangements in mucoepidermoid carcinoma, MYB rearrangements in adenoid cystic carcinomas, and EWSR1 rearrangements in hyalinizing clear cell carcinomas and myoepithelial tumors have been identified. These molecular alterations might be helpful in the distinction of these salivary gland tumors from other neoplasms in the lung. However, the distinction from metastatic disease remains challenging. Awareness of these tumors and knowledge of available ancillary studies to confirm the diagnosis is important to avoid misdiagnosis which might lead to differences in treatment, management, and prognosis. Further studies are needed to identify biomarkers to better predict patient's outcome and for individual management and treatment of patients.

Primary salivary gland tumors of the lung: Two cases date report and literature review

Background

Primary salivary gland-type tumors of the lung (PSGTTL) is a rare intrathoracic malignant tumor that accounts for all lungs <1% of tumors.

Purpose

To introduce two case reports of primary lung salivary gland tumors, and highlight their diagnosis and treatment challenges.

Case report

The first case was a 30-year-old female, who complained of repeated coughing and dyspnea for 1 year and worsening for 2 days. Chest CT and bronchoscopy showed new organisms in the lower part of the trachea, that the bronchus obstruction accounted for 70%. The biopsy histology revealed a adenoid cystic carcinoma. She underwent extensive surgical resection and multiple radiotherapy, and She is recovering well from follow-up. The second case was a 70-year-old man, who complained of intermittent sputum blood for 2 years, worsening hemoptysis and chest tightness for 3 months. The new organisms was found in the upper trachea from Chest CT and bronchoscopy, and histological biopsy was used to diagnose epithelial myoepithelial carcinoma. He underwent twice bronchoscopy thermal ablation treatments. The follow-up is currently in good condition.

Conclusion

Primary lung salivary gland tumors are considered to be rare malignant tumors in the lungs. Early detection is advocated as late presentation with advanced tumor presents diagnostic and therapeutic challenges.

[A Rare Case of Pulmonary Epithelial-myoepithelial Carcinoma: Case Report and Literature Review]

背景与目的

肺上皮-肌上皮癌（pulmonary epithelial-myoepithelial carcinoma, P-EMC）是一种十分罕见的涎腺型肺肿瘤，尚无标准治疗方案，本文拟分析肺上皮-肌上皮癌的临床特点，探讨肺上皮-肌上皮癌的诊疗方案。

方法

分析1例肺上皮-肌上皮癌患者的临床资料并回顾其他相关临床文献。

结果

上皮细胞免疫组化表达细胞角蛋白，肌上皮细胞免疫组化表达SMA及S-100，二代基因测序以HRAS基因突变为主，PD-L1蛋白为阴性。

结论

肺上皮-肌上皮癌大多预后良好，诊断以镜检及免疫组化为主，治疗以手术切除为主，放化疗效果尚不明确。

Pulmonary epithelial-myoepithelial carcinoma without AKT1, HRAS or PIK3CA mutations: a case report

Background

Pulmonary epithelial–myoepithelial carcinoma is a rare subtype of lung cancer. Because of its rarity, the molecular information on this carcinoma is insufficient.

Case presentation

We report a case of pulmonary epithelial–myoepithelial carcinoma without AKT1, HRAS or PIK3CA mutations in a 76-year-old woman. Computed tomography revealed a tumor located in the left lower lung. Thoracoscopic left lower lobectomy was performed. Histopathologically, the tumor consisted of duct-like structures and polygonal and spindle cell features. The duct-like structures were composed of two distinct cell layers. The inner layer consisted of cuboidal cells that were positive for pan-cytokeratin and negative for p63, whereas the outer layer consisted of polygonal and spindle cells that were positive for p63 and weakly positive for pan-cytokeratin. We evaluated mutations in AKT1, BRAF, CTNNB1, HRAS, KRAS and PIK3CA but did not detect any mutations.

Conclusion

Pulmonary epithelial–myoepithelial carcinoma is a rare subtype of lung cancer, with only 56 previous cases reported in the English literature. The genetic alterations in pulmonary epithelial–myoepithelial carcinoma are still unknown. We examined the 6 genes mutation analysis, however no mutation was detected.

Bronchoscopic management of a primary endobronchial salivary epithelial-myoepithelial carcinoma: A case report

Here, we discussed a 55 y/o African man who recently immigrated from Nigeria to the United States and who presented to Parkland Memorial Hospital with a productive, intermittent cough of one year duration. The cough was associated with shortness of breath and chest pain. Cough was not associated with voice hoarseness, hemoptysis, melanoptysis, and wheezing. He had a computed tomography (CT) scan of the chest that showed a 1.9 cm mass in the right main stem bronchus with ipsilateral right lower lobe consolidation and bronchiectasis. The patient was seen by pulmonology who recommended bronchoscopy for diagnosis and possible intervention. Bronchoscopy showed a 90% obstructing mass in the proximal right mainstem bronchus and bronchus intermedius. The mass was large and endobronchial, circumferential, exophytic, and polypoid. The decision was made to undergo bronchoscopic tumor ablation using electrocautery snare, argon plasma coagulation (APC), suction, and forceps. The tumor was successful ablated. Microscopic examination revealed eosinophilic ducts tightly coupled with a surrounding layer of clear cell myoepithelial cells and the diagnosis of epithelial-myoepithelial carcinoma (EMC) of the lung was made. The patient was discharged from the hospital with scheduled outpatient visits for monitoring of the carcinoma by pulmonology and thoracic surgery. Unfortunately, he was lost to follow up.

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Primary salivary epithelial-myoepithelial carcinoma are extremely rare malignancies found in the airways.

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This type of tumor can be seen in patients who present with chronic cough without other symptomatology.

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Although management is primarily surgical, here we report the successful bronchoscopic removal of this malignancy.

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There were no complications following the bronchoscopic removal of the tumor.