Primary epithelial-myoepithelial carcinoma of lung: a case report of a rare salivary gland type tumour

Primary Epithelial-Myoepithelial Carcinoma of the Lung Presenting as Multiple Synchronous Lesions

Primary epithelial-myoepithelial carcinoma of the lung is an extremely rare histologic form that originates in the bronchial glands. Pulmonary epithelial-myoepithelial carcinoma in the peripheral lung is extremely rare, and multiple primary pulmonary epithelial-myoepithelial carcinoma has not been reported to date. Here, we report a case of pulmonary epithelial-myoepithelial carcinoma presenting as multiple synchronous lesions. The patient underwent two treatments by video-assisted thoracic surgery within 3 years. At the 4-month follow-up, the patient had no evidence of recurrence. In conclusion, our case report may contribute to the understanding of pulmonary epithelial-myoepithelial carcinoma.

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.

Adenomyoepithelioma of the breast: a proposal for classification

Breast lesions with a prominent myoepithelial cell component constitute a heterogeneous group of benign and malignant neoplastic proliferations. These lesions are often dual epithelial-myoepithelial, but may be purely myoepithelial cell in nature. Benign epithelial-myoepithelial lesions typically maintain the morphology and immunophenotype of the normal bilayer epithelial myoepithelial structures. However, the distinction between the two cell components is not always clear-cut in malignant lesions in which the histogenesis of myoepithelial cells remains uncertain. Neoplastic biphasic epithelial-myoepithelial lesions of the breast include adenomyoepithelioma (AME), pleomorphic adenoma and adenoid cystic carcinoma. Four histological patterns of classical AME have been described: tubular, lobulated, spindle-cell and adenosis variants. Overlapping patterns occur and some AMEs display an intraductal papillary pattern that may represent a fifth variant. AME can be benign or malignant. Classical AME may show atypical features, which are not sufficient for the diagnosis of malignancy (atypical AME). Atypical AME is recognised as a lesion of uncertain malignant potential with limited metastatic capability. Based on the histological features, we propose a classification of malignant AME (M-AME) into three variants: M-AME in situ, M-AME invasive and AME with invasive carcinoma. In this review, we provide an overview of myoepithelial lesions of the breast focusing on the classification of AME to improve not only the consistency of reporting but also help to guide further management decision-making.

[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。

Challenges in diagnosis of pulmonary mucoepidermoid carcinoma: A case report

RATIONALE

Pulmonary mucoepidermoid carcinomas (PMECs) of the lung are rare malignant tumors. Despite progresses in examinations, the tumor represents a diagnostic challenge for pathologists and clinical physicians. Here, we present a patient who was eventually diagnosed with PMEC by the bronchoscopic examinations conducted three times.

PATIENT CONCERNS

We present the case of a 41-year-old female who was initially diagnosed with pulmonary pleomorphic adenoma (PPA) with a 68 × 82 mm mass and nodules in her lung and eventually diagnosed with PMEC.

DIAGNOSES

Based on histopathology, immunohistology, and imaging studies, the patient was diagnosed with PMEC (pT4N2M1).

INTERVENTIONS

The patient received first-line systemic chemotherapy regime (gemcitabine combined with carboplatin).

OUTCOMES

The patient received 2 cycles of chemotherapy. Based on the response evaluation criteria in solid tumor, she achieved partial response, and the mass was distinctly decreased from 68 × 22 mm to 41 × 17 mm.

LESSONS

This case presents a rare PMEC overlapping with PPA, based on histological findings, suggesting that besides imaging studies and laboratory examinations, multiple biopsies and ThinPrep cytology tests are necessary to obtain an accurate diagnosis. The patient showed positive response to chemotherapy.

Sinonasal epithelial-myoepithelial carcinoma: Report of a novel subsite and review of the literature

BACKGROUND

Epithelial-myoepithelial carcinoma (EMC) is a rare tumor of the major and minor salivary glands. Sinonasal EMC is extremely uncommon and hitherto not described within the frontal or ethmoid sinuses.

OBJECTIVE

To present a novel sinonasal subsite and review the literature regarding sinonasal EMC.

METHODS

A case of frontoethmoidal EMC was presented. A medical literature data base was queried from January 1, 1950, to August 8, 2017, for all reports of sinonasal EMC.

RESULTS

A 69-year-old man underwent combined open and endoscopic craniofacial resection of a right frontoethmoidal EMC, a previously undescribed primary location for this tumor. A comprehensive review of the literature revealed 13 additional cases of sinonasal EMC.

CONCLUSION

EMC is an uncommon neoplasm typically found in the major salivary glands; occurrence in the nose or paranasal sinuses is extremely rare. EMC often follows an indolent clinical course, although, in a minority of cases, particularly in large tumors with nuclear atypia, more aggressive behavior may be observed.

A rare case of primary peripheral epithelial myoepithelial carcinoma of lung: Case report and literature review

BACKGROUND

Primary salivary gland-type tumors of lung are rare. Epithelial-myoepithelial carcinoma (EMC) of the lung is a minor salivary gland-type tumor subtype.

METHODS

We report a very rare case of EMC located in the peripheral left lower lobe that was diagnosed in a 58-year-old man and this is the first study in which we summarize all the patients with primary peripheral lung EMC concerned with the clinical features. Informed consent was obtained from the patient.

RESULTS

Chest computed tomography displayed an anomalous soft tissue mass with slightly lobular borders in the peripheral segment of the left lower lobe and closed to the visceral pleura. The surgery was performed by using video-assisted thoracic surgery. Grossly, the tumor was solitary, well-circumscribed, and unencapsulated endobronchial lesion. A microscopic examination revealed that it was circumscribed, although the tumor borders may show single cells or clusters of cells proliferating away from the main tumor mass. The inner tubular layer showed epithelial cell characteristics, whereas the outer layer exhibited myoepithelial cell characteristics. Immunostaining for P40, P63, and cytokeratin 5/6 was positive. However, the anaplastic lymphoma kinase-V, thyroid transcription factor-1, synaptophysin, chromogranin A and napsin A were negative.

CONCLUSIONS

Literature review showed that most of patients with peripheral EMC were asymptomatic. Computed tomography and magnetic resonance imaging scans are able to indicate the presence of peripheral EMC. Pathological analysis is an effective method to clarify the diagnosis. Surgery is a regular treatment method. To facilitate the preoperative diagnosis and avoid the misdiagnosis of such a rare disease, more cases will need to be reported.