Pulmonary Epithelial-Myoepithelial Tumor of Unproven Malignant Potential: Report of a Case and Review of the Literature

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.

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.

Diagnostic Significance of HRAS Mutations in Epithelial-Myoepithelial Carcinomas Exhibiting a Broad Histopathologic Spectrum

Epithelial-myoepithelial carcinoma (EMC) is a rare salivary gland tumor that is histologically characterized by biphasic tubular structures composed of inner ductal and outer clear myoepithelial cells. Because of its histologic variety, it is sometimes challenging to make an accurate diagnosis, and useful ancillary tests are essential for this purpose. We investigated 87 cases of EMC arising in the major and minor salivary glands and seromucinous glands in the nasal cavity or bronchus to describe the histologic features and mutation status of selected key oncogenes. Classic EMC accounted for 40.2% of all cases. Other cases showed various growth patterns and cytologic features in addition to the typical histology; cribriform patterns, a basaloid appearance, and sebaceous differentiation were relatively common (17.2% to 18.4%), whereas oncocytic/apocrine, papillary-cystic, double-clear, squamous, psammomatous, Verocay-like, and high-grade transformation were rare. HRAS mutations were found in 82.7% of EMCs and were concentrated in codon 61. There was no significant correlation between the HRAS mutation status and the histology. No EMC ex pleomorphic adenoma cases had HRAS mutations. PIK3CA and/or AKT1 mutations were the second most frequent mutations (20.7%, 6.5%, respectively) and almost always cooccurred with HRAS mutations. It is noteworthy that the HRAS mutation was not identified in any salivary gland tumor entities manifesting EMC-like features, including adenoid cystic carcinoma, pleomorphic adenoma, basal cell adenoma/adenocarcinoma, and myoepithelial carcinoma. We conclude that HRAS mutations are a frequent tumorigenic gene alteration in EMC, despite its histologic diversity. This study provides further insight into strategies for diagnosing EMC and discriminating it from its mimics.

Adenomyoepithelioma of the breast with late pulmonary metastases - case report and review of the literature

Background

Adenomyoepithelioma (AME) of the breast is a rare tumour of unpredictable clinical behaviour. Most of the tumours are benign with some giving local recurrences or distant metastases.

Case Presentation

We report a case of late lung metastases in a woman with a history of breast adenomyoepithelioma. Partial lobectomy was performed for lung lesions and initial diagnosis was epithelial-myoepithelial carcinoma.

Conclusion

Careful slide’s revision of both breast and pulmonary lesions showed identical microscopic appearance with lung tumour performing more malignant features. Tumour cells in both: breast and pulmonary lesions were positive for cytokeratin and EMA (epithelial cells) and also for SMA, S100 and vimentin (myoepithelial cells). Two years and 7 months follow-up showed no recurrent neoplastic disease in our patient.

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.

Primary Pulmonary Salivary Gland-type Tumors: A Review and Update

Pulmonary salivary gland-type tumors (SGT) comprise a very small proportion of primary lung neoplasms. The most common tumors among this group are mucoepidermoid carcinoma and adenoid cystic carcinoma. Contrary to the head and neck region, benign SGT such as pleomorphic adenomas are exceedingly rare in the pulmonary system. More recently, 2 additional SGT, namely hyalinizing clear cell carcinoma and salivary duct-like carcinoma were recognized as primary lung tumors expanding the spectrum of SGT that have been described to originate in the tracheobronchial system. Primary pulmonary SGT must be clinically excluded from metastatic salivary gland neoplasms as their morphology is indistinguishable from that of their salivary gland counterparts. Little is known about the clinical behavior and best treatment approach for these unusual tumors. In this review, we provide a comprehensive summary of primary pulmonary SGT with particular emphasis on morphologic characteristics and latest developments in terms of immunohistochemical and molecular techniques.

A Rare Case of Bronchial Epithelial-Myoepithelial Carcinoma with Solid Lobular Growth in a 53-Year-Old Woman

Epithelial-myoepithelial carcinoma (EMC) of lung is a minor subset of salivary type carcinoma of lung of known low grade malignancy. Histologically, two-cell components forming duct-like structure with inner epithelial cell layer and outer myoepithelial cell layer are characteristics of EMC. In salivary gland, dedifferentiation of conventional low grade malignancy has been reported and is thought to be related with poor prognosis. However, precise histomorphology and prognostic factors of pulmonary EMC have not been clarified due to its rarity. Herein, we reported a rare case of EMC presented as endobronchial mass in a 53-year old woman, which showed predominant solid lobular growth pattern and lymph node metastases.

Primary epithelial-myoepithelial carcinoma of the lung: A case report demonstrating high-grade transformation-like changes

Primary salivary gland-type tumors of the lung are rare; among them, epithelial-myoepithelial carcinomas (EMC) represent a minor histological subtype. The present case documents an EMC that occluded the B8 segment of the left lung in a 72-year-old woman. Macroscopically, the tumor was well-demarcated; however, microscopic examination demonstrated that it had infiltrated the lung parenchyma. The majority of the tumor mass was composed of a myoepithelial overgrowth in conjunction with conventional bilayered ductal structures comprising epithelial and myoepithelial cells. At the advancing edge of the tumor, the myoepithelial overgrowth was observed to be gradually transitioning to a higher-grade component, which demonstrated venous invasion. The Ki-67 labeling index was reduced compared with high-grade transformation (HGT) of salivary gland EMC; p53 was sparsely observed on immunostaining. However, cyclin D1, which is reported to be overexpressed in certain subtypes of salivary gland carcinomas with HGT, was overexpressed in the higher-grade component of the tumor, indicating a potential HGT initiation. The surgical margin was tumor free, and no recurrence has been observed for 4 months. A thorough follow-up is required considering the HGT-like changes and venous invasion of the tumor. Additional studies are required to elucidate the characteristics of pulmonary EMC, with an emphasis on detecting HGT or HGT-like changes.

Epithelial-myoepithelial carcinoma of the trachea-a rare entity case report

Epithelial-myoepithelial tumors of the lung are rare neoplasms whose biological behavior and clinical course still remain to be defined. Epithelial-myoepithelial carcinoma (EMCa) is a low-grade malignant tumour. According to literature, most commonly occurs in salivary glands, particularly in parotic gland, but it can also occur in unusual locations such as breast, lachrymal gland, nose, paranasal sinus, lung, bronchus and, as in our case, trachea. There are no many documented case reports of a primary myoepithelial carcinoma in the trachea. We report a case of a 34-year-old man diagnosed with this unusual location of an epithelial-myoepithelial tumor. The tumour was removed by segmental tracheal resection and end-to-end anastomosis.

Primary epithelial myoepithelial lung carcinoma

Primary epithelial-myoepithelial carcinoma (EMC) of the lung is an extremely rare neoplasm that originates from submucosal bronchial glands and has been found in the salivary glands, breast tissue, and sweat glands. However, only a few cases in the respiratory tract have been identified. In the literature, most pulmonary EMCs have been reported to have developed endobronchially although a few EMC cases have been presented as intraparenchymatous tumors. We have identified a case of primary EMC that developed in the peripheral lung parenchyma.

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.

Epithelial-myoepithelial tumour of the lung: a case report referring to its molecular histogenesis

Tracheobronchial submucous glands can be considered the pulmonary equivalent of minor salivary glands and therefore they can develop most of the tumours originated in these. Nevertheless, in spite of the wide distribution of this kind of glands along the tracheobronchial tree, pulmonary salivary gland-like neoplasms are not very frequent. Among them, the most frequent are mucoepidermoid and adenoid cystic carcinomas. On the contrary, pulmonary neoplasms showing a mixture of epithelial and myoepithelial elements are extraordinary infrequent, with only 11 cases collected from literature.

We present the case of a 76 year-old woman with no interesting pathological history, to whom a pulmonary nodule is detected during a study of unknown origin neutropenia. An upper right lobectomy is performed.

After macro and microscopic study, the diagnosis of pulmonary epithelial-myoepithelial tumour is made. It is a low malignant potential tumour with capacity to locally recur and less frequently to metastasize. Our case has the peculiarity of not being connected neither to visceral pleura nor to bronchial tree; we have not found this characteristic in any literature reviewed case.

These tumours have been named in a lot of different ways, including adenomyoepithelioma, epithelial-myoepithelial tumour, epithelial-myoepithelial carcinoma or epithelial-myoepithelial tumour of uncertain malignant potential.

The p27/kip-1 protein plays a fundamental role in the development of these neoplasms. As we have verified in our case, its aberrant cytoplasmic location, besides its proved oncogenic function, would favour the proliferation of stem cells, which would explain both dual phenotype with presence of myoepithelial cells without connection with the bronchial tree, and TTF-1 immunostaining in epithelial cells.

Skull metastasis as initial manifestation of pulmonary epithelial-myoepithelial carcinoma: a case report of an unusual case

Epithelial-myoepithelial carcinoma (EMC) of the lung is rare and is considered to be low-grade malignancy. Intracranial metastasis of pulmonary EMC has not previously been reported according to our search of the literature. We report a case of skull metastasis as the initial manifestation of pulmonary EMC. An 81-year-old man complained of left leg motor weakness. Neurological examination showed left hemiparesis. Computed tomography and magnetic resonance imaging revealed an osteolytic tumor in the right frontal bone with invasion to the dura and subdural space, attached to the superior sagittal sinus. Subtotal removal of the tumor was performed, and the left hemiparesis showed improvement. Histopathological study revealed the tumor to consist of epithelial and myoepithelial cells. Pulmonary EMC was diagnosed. The MIB-1 index in primary lesion was approximately 10%. The skull and dura are possible sites for metastasis from pulmonary EMC. The MIB-1 index is a predictive marker of malignant potential.

Primary myoepithelial carcinoma of the lung: a rare entity treated with parenchymal sparing resection

Primary lung myoepithelial carcinomas are rare neoplasms arising from the salivary glands of the respiratory epithelium. Given the rare occurrences and reports of these tumors, appropriate recommendations for resection are difficult to formulate. Although classified as low-grade neoplasms, these tumors have a significant rate of recurrence and distant metastasis.

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.

Alteration of the E-cadherin/beta-catenin cell adhesion system is common in pulmonary neuroendocrine tumors and is an independent predictor of lymph node metastasis in atypical carcinoids

BACKGROUND

To the authors' knowledge, little is known regarding the role of E-cadherin/beta-catenin system dysregulation in pulmonary neuroendocrine tumors.

METHODS

E-cadherin and beta-catenin immunoreactivity was evaluated in 10 hyperplastic neuroendocrine tumorlets and 210 neuroendocrine tumors, including 96 typical carcinoids (CTs), 35 atypical carcinoids (ACTs), 49 large cell neuroendocrine carcinomas (LCNECs), and 30 small cell lung carcinomas (SCLCs).

RESULTS

Normal and hyperplastic bronchial neuroendocrine cells expressed E-cadherin/beta-catenin with an orderly distribution along the cell membrane. Neuroendocrine tumors retained beta-catenin expression in all tumors and E-cadherin in most tumors, with the exception of 2% of LCNECs, 3% of SCLCs and 9% of ACTs. E-cadherin showed a prevalent membrane-associated, linear immunoreactivity in CTs, whereas membrane-disarrayed and cytoplasmic staining was seen in most ACTs, LCNECs, and SCLCs (P < 0.001). beta-Catenin exhibited similar immunoreactivity patterns according to tumor type and a close association with E-cadherin subcellular distribution (P < 0.001). Nuclear accumulation of beta-catenin was found only in seven LCNECs and in two SCLCs. In ACTs, disarrayed immunoreactivity for E-cadherin and/or beta-catenin was associated with a nontrabecular growth pattern, altered expression of the cell-motility marker fascin, and lymph node metastases. Furthermore, a disarrayed E-cadherin distribution pattern was associated with the pathologic lymph node classification and the number of involved lymph nodes. Multivariate analysis confirmed that a disarrayed E-cadherin or beta-catenin pattern was an independent predictor of lymph node metastases in patients with ACT.

CONCLUSIONS

The subcellular compartmentalization of the E-cadherin/beta-catenin complex was altered in pulmonary neuroendocrine tumors. This likely affects the tumor growth pattern and cell motility of ACT and was correlated with the occurrence of lymph node metastases.

[Broncho-pulmonary adenomas]

Adenomas of solitary gland type together with papillomas are the true benign tumours in or around the bronchial tree. Alveolar adenoma and papillary adenoma are more frequently observed in peripheral parenchime although this group of tumours is very rare and often incidentally diagnosed. Presenting usually as solitary nodules in adults after 45 years, are easily recognized because of distinct morphology but alveolar adenomas may be difficult to evaluate in frozen sections. Two cases of pleomorphic adenoma and alveolar adenoma are presented and a review of literature is made.

Bronchial Epithelial-Myoepithelial Carcinoma

Epithelial-myoepithelial tumor is extremely rare as a pulmonary neoplasm. Only 20 cases have been reported to date, of which 14 were malignant. We report a case of intrabronchial epithelial-myoepithelial carcinoma in a 73-year-old man with a history of heavy smoking. The tumor was well-circumscribed and caused distal airway obstruction. Histologically, the tumor showed glandular and solid architecture. The glands were composed of an inner layer of epithelial cells and an outer layer of myoepithelial cells. The solid areas consisted of spindle-shaped myoepithelial cells. Immunohistochemical staining was positive for p53 and c-Kit (CD117). Focal atypia and increased mitotic activity were present, but no vascular invasion or nodal metastasis was identified.

Salivary-type neoplasms of the breast and lung

Salivary-type tumors occur in multiple sites in the human body, likely related to a basic structural homology between exocrine glands in these different anatomic areas. This paper reviews these salivary gland tumor types in breast tissue and lung. Salivary-type tumors of both breast and lung are relatively uncommon in comparison to their salivary gland counterparts. This may be attributable in part to lack of familiarity with these tumors in extra-salivary sites, and in part to histologic overlap with other primary and metastatic tumor types. Recognition of these entities is improving as the clinical and pathologic features are better delineated, and tumors are more accurately classified. Prediction of malignant behavior is not always possible in these unusual sites. In some instances, such as adenoid cystic carcinoma, behavior is known to differ considerably from that of analogous primary salivary gland tumors and in other instances there are simply too few reported cases to allow for adequate prognostication. In fact, more recent papers discuss the need to consider a spectrum encompassing benign and malignant lesions, in both breast and lung. Of course, some entities show clear-cut evidence of malignancy with documented potential for metastasis, others show bland features and well-reported benign behavior, and the less well-defined entities reside between these two extremes. The molecular pathology of salivary gland tumors has been reasonably well investigated in that location; however; there are few molecular studies devoted to salivary-type tumors of the breast and lung. This represents a potential area for future growth in further clarifying these tumors and their behavior.

Epithelial-myoepithelial carcinoma of the lung. A case report and review of the literature

Primary lung tumors mimicking the salivary gland-type neoplasms are extremely rare. These types of tumors originate from submucosal bronchial glands. Epithelial-myoepithelial carcinoma is an uncommon tumor in this group, and only 7 cases have been reported. It is considered to be a low-grade malignant neoplasm. We report a case of epithelial-myoepithelial carcinoma of bronchial gland origin in a 73-year-old man who presented with coughing and dyspnea. The bronchus of the left lower lobe contained a tumor mass that had a polypoid growth pattern. The tumor also extended into the pulmonary parenchyma, forming a well-circumscribed mass with a pushing margin. The tumor consisted of epithelial and myoepithelial cells. The epithelial cells were positive for cytokeratins and epithelial membrane antigen, while the myoepithelial cells were positive for S100 protein and muscle-specific actin. According to these findings, we diagnosed epithelial-myoepithelial carcinoma. After undergoing pneumonectomy, the patient has been disease free for 34 months.

Epithelial and soft tissue tumors of the tracheobronchial tree

This article provides a broad overview of tumors that can involve the tracheobronchial tree. For the most part, the clinical, radiographic, and endoscopic presentation of these rare tumors does not differ significantly from the more common tumors of the lung. Appropriate classification of many tracheobronchial tumors ultimately requires complete sampling and a thorough microscopic evaluation. The introduction of ancillary diagnostic techniques such as immunohistochemistry and molecular analysis will continue to refine tumor classification.

P63 is expressed in basal and myoepithelial cells of human normal and tumor salivary gland tissues

p63 is essential for epithelial cell survival and may function as an oncogene. We examined by immunohistochemistry p63 expression in human normal and tumor salivary gland tissues. In normal salivary glands, p63 was expressed in the nuclei of myoepithelial and basal duct cells. Among 68 representative salivary gland tumors, 63 displayed p63 reactivity. In all tumor types differentiated towards luminal and myoepithelial lineages (pleomorphic adenomas, basal cell adenomas, adenoid cystic carcinomas, and epithelial-myoepithelial carcinomas), p63 was expressed in myoepithelial cells, whereas luminal cells were always negative. Similarly, in mucoepidermoid carcinomas, basal, intermediate, and squamous cells expressed p63, in contrast to luminal mucous cells. p63 reactivity was also restricted to basal cells in Warthin tumors and oncocytomas. Myoepitheliomas and myoepithelial carcinomas all expressed p63. The only five negative tumors were three of four acinar cell carcinomas and two of three adenocarcinomas. In conclusion, p63 is expressed in the nuclei of normal human salivary gland myoepithelial and basal duct cells. p63 expression is retained in the modified myoepithelial and basal cells of human salivary gland tumors, which suggests a role for p63 in oncogenesis of these complex tumors.

Epithelial-myoepithelial carcinomas of the bronchus

Epithelial-myoepithelial carcinomas are very rare in the lung, and little is known about the relationship of their histologic features to prognosis. We describe five primary pulmonary epithelial-myoepithelial carcinomas with details on clinical presentation, histology, and immunohistochemical profiles. We also reviewed the literature to detail further their prognosis. The patients' ages ranged from 33 to 57 years (average 51 years). The tumors were all endobronchial and the patients presented with symptoms or imaging features of airway obstruction. The tumors were completely resected; none showed nodal involvement. All five patients are alive and free of disease 4 months to 8 years (average 4.2 years) after surgery. Four tumors showed a mixed pattern of glands lined by a dual layer of cells and solid sheets of either spindle cells or clear cells, the glandular and solid components being present in variable proportions. The fifth tumor comprised purely spindle cells. The mitotic rate was <1/20 high power fields in both the glandular and spindle/clear cell components. In one case there was focal nuclear pleomorphism. The inner layer of the glands stained for cytokeratins and epithelial membrane antigen, and the outer layer for S-100 and smooth muscle actin. In one case the spindle cells stained for CD34. A review of published cases shows the majority of tumors behave in an indolent fashion, the rare aggressive tumors being predominantly myoepitheliomatous. Nevertheless, the term epithelial-myoepithelial carcinoma is preferred because of their malignant potential. A high mitotic rate, tumoral necrosis, and nuclear pleomorphism appear to be adverse prognostic factors.