Bronchial 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.

Epithelial-myoepithelial carcinoma of the lung: a case report

BACKGROUND

Pulmonary epithelial-myoepithelial carcinoma (P-EMC) is a rare subset of salivary gland-type tumors of the lung. Because of its rarity and unproven malignant potential, the optimal therapy for P-EMC has not been defined. Here, we report a typical case of P-EMC and a review of the literature to consider appropriate treatment.

CASE PRESENTATION

A 54-year-old woman presented with an abnormal lung shadow on a routine chest X-ray. A chest computed tomography (CT) scan verified an 18-mm endobronchial nodule on the middle lobe. We performed a bronchoscopic biopsy, and the patient was diagnosed with P-EMC. After confirming the absence of tumors in the salivary glands, she underwent a right middle lobectomy along with hilar and mediastinal lymph node dissections. Currently, the patient is doing well, without any sign of recurrence 3 years after surgery.

CONCLUSIONS

Although a majority of P-EMC cases, as in our case, behave indolently, several poor progression cases have been reported. For distinguishing the minor malignancy cases from others, histological findings such as myoepithelial anaplasia could be a predictive factor. Complete resection is needed to evaluate the whole tumor, because P-EMCs often show histological heterogeneity. Moreover, incomplete excision may be a poor prognostic factor. Although lobectomies as well as lymph node dissections, sleeve lobectomies, or pneumonectomies are routinely performed for complete resection, further investigation is required to establish the optimal treatment strategy.

Primary epithelial myoepithelial carcinoma of lung, reporting of a rare entity, its molecular histogenesis and review of the literature

Primary epithelial myoepithelial carcinoma of lung is a rare entity and is thought to arise from the submucosal bronchial glands distributed throughout the lower respiratory tract. Because of the rarity of this tumor, we describe one case of epithelial myoepithelial carcinoma arising in the bronchus intermedius and presenting as an endobronchial mass. A 57-year-old male patient presented with an incidental finding of an endobronchial mass located in the lumen of the right lower lobe bronchus and caused near total luminal occlusion of the bronchus. An endobronchial carcinoid tumor was entertained clinically. Subsequently the patient underwent an uneventful videothoracoscopic lobectomy of lower and middle lobes of the right lung. Morphologically and immunohistochemically the tumor was characterized by two cell populations with epithelial and myoepithelial cells forming duct-like structure. The final diagnosis of epithelial myoepithelial carcinoma of lung was rendered.

Primary adenomyoepithelioma of tonsil

We present a case of adenomyoepithlioma (AME) arising from the tonsil. AME is an uncommon tumor that typically arises in breast, but rarely found in salivary glands, lung, and skin. Its biological features have not been thoroughly characterized. Here we describe a primary AME originating from the tonsil. The pathologic changes were characterized by hypercellularity, the dominance of both epithelial and myoepithelial cells. Malignancy was evidenced by the presence of a high mitotic rate and invasive growth. The epithelial cells express high levels of cytokeratin and epithelial membrane antigen (EMA). The myoepithelial cells show positive staining for calponin, p63, vimentin, and S-100. A thorough review of the literature indicates that this is likely the first reported case of AME from the tonsil. Following descriptions of the diagnosis, treatment, and prognosis of this specific case, pathologic and clinical characteristics of AME from other tissues are also compiled and discussed.

Pneumocytic Adenomyoepithelioma: A Distinctive Lung Tumor With Epithelial, Myoepithelial, and Pneumocytic Differentiation

Pulmonary tumors with epithelial and myoepithelial differentiation are rare, thought to be of bronchial minor salivary gland origin and classified similarly to salivary gland neoplasms. We report a series of a distinctive subtype of pulmonary glandular tumors showing epithelial and myoepithelial differentiation with further pneumocytic specialization. All patients were women, aged 52 to 63 years and presented with single or multiple pulmonary nodules. The tumors were grossly circumscribed, 0.8 to 2.6 cm in greatest dimension, and histologically showed glandular and spindle cell differentiation. Some glands were filled with colloidlike secretion and had an inner, cuboidal epithelial cell layer (pankeratin, epithelial membrane antigen, and thyroid transcription factor-1 positive), surrounded by an outer layer of myoepithelial cells merging with foci of spindled myoepithelial cells (high molecular weight keratin, S100, smooth muscle actin, calponin, caldesmon, and p63 positive). There were also some glands lined by a single layer of plump cells that were positive for surfactant protein-A in addition to the other epithelial cell markers. Electron microscopy confirmed pneumocytic features in these cells and the myoepithelial nature of the spindled cells. The surgery in all cases was wedge resection of the masses. The biologic behavior to date has been benign. This is the first reported series of a distinctive lung tumor with epithelial, myoepithelial, and pneumocytic differentiation that differs histologically from all previously recognized pulmonary salivary gland-type and pneumocytic tumors. It is a unique benign appearing neoplasm for which the designation pneumocytic adenomyoepithelioma is suggested.

Bronchial epithelial-myoepithelial carcinoma

An epithelial-myoepithelial tumor is an extremely rare pulmonary neoplasm. Only 21 cases have been reported to date. This report presents a case of left main bronchial epithelial-myoepithelial carcinoma in a 43-year-old woman. No mediastinal lymph nodes were enlarged in computed tomographic scan, and no tumor growth was noted beyond the bronchial cartilage layer by endobronchial ultrasound imaging. This report highlights the usefulness of endobronchial ultrasound imaging for determining the depth of tumor invasion and choosing an alternative approach to surgical resection.

Detection of C-KIT (CD117) molecule in benign and malignant salivary gland tumours

C-KIT (CD117), a tyrosine kinase receptor, is involved in the growth and development of normal tissues and some types of neoplasms. In the present study we analysed the expression of this molecule in salivary gland tumours. Archival formalin-fixed, paraffin-embedded sections of 40 benign and 57 malignant salivary gland tumours were retrieved and retrospectively studied immunohistochemically using a polyclonal C-KIT antibody in an Envision/HRP technique. In addition five samples of chronic submandibular sialadenitis, five normal minor salivary glands and parotid or submandibular gland tissue adjacent to benign tumour were also studied. C-KIT expression was observed in cases of adenoid cystic, acinic cell polymorphous low grade, epithelial-myoepithelial, carcinosarcoma and basal cell adenocarcinomas, as in luminal cells of pleomorphic adenomas, in serous acinar and only in intercalated and a small number of striated ductal cells of inflammatory salivary gland tissue, whereas normal salivary lobules were generally negative except a weak positivity of intercalated cells. Contrary to other reports, this study suggests that, C-KIT protein does not appear to be an exclusively specific marker for benign or malignant salivary gland neoplasms, but may be useful in differential diagnosis of adenoid cystic carcinoma from polymorphous low grade adenocarcinoma. Furthermore its expression in serous acinar cells in sialadenitis and intercalated ductal cells in normal and inflammatory lesions may indicate a possible participation in pathogenesis of both neoplastic and non-neoplastic salivary gland diseases.