Metastatic low-grade myoepithelial carcinoma of lung managed with low-dose external beam radiotherapy.

Myoepithelial tumor of lung is a rare tumor; the histopathological findings resemble the myoepithelial tumors of the salivary gland. Distinguishing low-grade nonmetastatic myoepithelial carcinoma from benign myoepithelioma can be challenging both radiologically and histomorphologically. We present a case report of a low-grade myoepithelial carcinoma of lung with contralateral lung metastasis which was treated with low-dose external beam radiotherapy.

MYB Translocation Status in Salivary Gland Epithelial-Myoepithelial Carcinoma: Evaluation of Classic, Variant, and Hybrid Forms.

Epithelial-myoepithelial carcinoma (EMC) is a malignant salivary gland neoplasm comprised of a biphasic arrangement of inner luminal ductal cells and outer myoepithelial cells. Adenoid cystic carcinoma (AdCC) is also a biphasic tumor comprised of ductal and myoepithelial cells, but these components tend to be arranged in a more cribriform pattern. The occurrence of "hybrid carcinomas" that show mixed patterns of EMC and AdCC raises questions about the relationship of these morphologically overlapping but clinically distinct tumors. AdCCs frequently harbor MYB-NFIB gene fusions. Mapping of EMCs (including hybrid forms with an AdCC component) for this fusion could help clarify the true nature of EMC as a distinct entity or simply as some variant form of AdCC. Twenty-nine cases of EMC were evaluated including 15 classic low-grade EMCs, 7 intermediate-grade EMCs, 2 EMCs with myoepithelial anaplasia, 1 EMC with high-grade transformation, and 4 hybrid EMCs with an AdCC component. Break apart fluorescence in situ hybridization for MYB was performed, as was MYB immunohistochemistry. For the hybrid carcinomas and those with high-grade transformation, the divergent tumor components were separately analyzed. A MYB translocation was identified in 5 of 28 (18%) tumors including 3 of 4 (75%) hybrid carcinomas and 2 of 7 (29%) intermediate-grade EMCs. For the positive hybrid carcinomas, the fusion was detected in both the EMC and AdCC components. The MYB fusion was not detected in any of the classic EMCs (0/15) or in any of the EMCs with myoepithelial anaplasia (0/2) or high-grade transformation (0/1). The fluorescence in situ hybridization assay was unsuccessful in 1 case. MYB immunostaining was seen in 5 of 5 fusion-positive cases, and also 9 of 23 fusion-negative tumors. Classic low-grade EMCs are genetically distinct from AdCCs in that they do not harbor MYB fusions. The presence of a MYB fusion in EMCs showing hybrid features of AdCC or exhibiting highly infiltrative growth points to a subset of these tumors that may well be true AdCCs masquerading as EMCs.

[Salivary gland-type lung tumor: An update]. / Tumeurs de type glandes salivaires du poumon.

"Salivary gland-type" tumors arising from the bronchi and lung are rare but not exceptional entities. They are mostly represented by malignant entities such as cystic adenoid carcinoma, mucoepidermoid carcinoma and epithelial/myoepithelial carcinoma. Benign tumors are rare, mainly encompassing pleomorphic adenomas, which are to differentiate from mucous gland adenomas, another entity arising specifically from the peri-bronchial glands. These tumours develop in the proximal bronchi and are not associated with smoke abuse. Their main treatment is surgery. It is important to differentiate them from other broncho-pulmonary tumours as they do not share the same prognosis and therapeutic. This article will review the WHO 2015 classification of these tumours as well as recent updates from the literature to help define diagnosis criteria for these uncommon entities.

Myoepithelioma-like Tumors of the Vulvar Region: A Distinctive Group of SMARCB1-deficient Neoplasms.

We describe 9 tumors that resemble soft tissue myoepitheliomas but possess certain traits that do not fit perfectly into this category. These tumors, herein referred to as "myoepithelioma-like tumors of the vulvar region," occurred in the subcutis of the vulva and surrounding regions of adult women aged 24 to 65 years. Histologically, the tumors measured 2 to 7.7 cm and were well circumscribed, focally encapsulated, and lobulated. Tumor cells had an epithelioid to spindled shape, with fine amphophilic cytoplasm, and uniform nuclei with vesicular chromatin and nucleoli. The tumor stroma was relatively hypervascular, and comprised a mixture of myxoid and nonmyxoid components. Myxoid areas accounted for <5% to 95% of the tumor volume, wherein cells proliferated singly or in a loosely cohesive manner. In nonmyxoid areas, tumors cells grew in diffuse sheets or storiform arrangements. Immunohistochemically, all tested tumors were positive for vimentin, epithelial membrane antigen, and estrogen receptor; most tumors expressed actin. All tumors were negative for S100 protein, glial fibrillary acidic protein, and CD34. Cytokeratin expression was absent in all but 2 tumors, which showed rare positivity. SMARCB1 expression was deficient in all cases. EWSR1, FUS, and NR4A3 rearrangements were absent. All tumors were treated through surgery. Although 3 tumors regrew or recurred after intralesional excision, all 9 patients were alive without metastases at a mean follow-up of 66 months. Myoepithelioma-like tumors of the vulvar region constitute a distinct group of tumors, although future research is required to determine whether they are an unusual subtype of soft tissue myoepitheliomas or a separate disease.

Recently characterized soft tissue tumors that bring biologic insight.

Previously unrecognized but clinicopathologically (and often molecularly) distinct types of soft tissue tumor continue to be characterized, allowing wider recognition, more consistent application of diagnostic criteria, more reliable prediction of tumor behavior and enhancement of existing classification schemes. Examples of such 'entities' that have become much better understood over the past decade or so include deep 'benign' fibrous histiocytoma, hemosiderotic fibrolipomatous tumor, PEComa, spindle cell liposarcoma, myoepithelial tumors of soft tissue and spindle cell/sclerosing rhabdomyosarcoma. These tumor types, as well as the insights which they have engendered, are briefly reviewed here.

Secretory myoepithelial carcinoma: a histologic and molecular survey and a proposed nomenclature for mucin producing signet ring tumors.

Signet ring cell (mucin producing) adenocarcinoma is a rare low grade salivary gland malignancy. While currently designated as an adenocarcinoma, myoepithelial differentiation has been implied in previously reported cases. We herein perform a survey of our cases of signet ring cell adenocarcinoma and review the literature in order to refine categorization of this rare tumor. Five cases were retrieved. One was reclassified as a mammary analogue secretory carcinoma, leaving four that fulfilled the criteria for signet ring cell adenocarcinoma: the presence of prominent signet ring or vacuolated cells arranged in islands, interconnecting strands, cords or sheets in a myxoid or hyaline stroma, or pools of mucin. An extensive panel of histochemical and immunohistochemical stains and fluorescence in situ hybridization (FISH) (modeled after common phenotypes and molecular alterations seen in signet ring and myoepithelial tumors at other sites) was performed. The male-to-female ratio was 3:1. The mean age was 56 years (range 18-81). Sites involved included buccal mucosa (2), soft palate (1) and deep parotid (1). Perineural and angiolymphatic invasion were present in three and two cases respectively. One patient was lost to follow up and the remainder were alive and without disease at time of last follow up (mean 38 months). All cases showed mucicarmine positive vacuolated/signet ring cells embedded in a myxoid stroma. Three cases showed at least focal p63 staining and two cases showed positivity for calponin. Membranous E-cadherin was retained in all cases. FISH was negative for ETV6, EWSR1, and ALK1 rearrangements in all four cases. Based on the current series and the previously reported cases, it is evident that signet ring adenocarcinomas have a dual secretory and myoepithelial phenotype and thus as a whole more appropriately designated as 'secretory myoepithelial carcinoma.' They behave in a fairly indolent fashion and do not share the major molecular alterations seen in other signet ring and myoepithelial tumor types.

Myoepithelial and epithelial-myoepithelial, mesenchymal and fibroepithelial breast lesions: updates from the WHO Classification of Tumours of the Breast 2012.

In the 4th edition of the WHO Classification of Tumours of the Breast, myoepithelial lesions are retitled myoepithelial and epithelial-myoepithelial lesions in order to better reflect the dual participation of luminal and myoepithelial compartments in some key entities. Malignant myoepithelioma, described as a section within the chapter on myoepithelial lesions in the 3rd edition, is recognised in the 4th edition as part of metaplastic carcinoma. Adenomyoepithelioma with malignancy is categorised in terms of the cellular component undergoing malignant transformation. The list of antibodies that can be used for identifying myoepithelial cells is updated. Among mesenchymal lesions, new additions are nodular fasciitis and atypical vascular lesions, while the haemangiopericytoma is removed. The 3rd edition stated that pathological prediction of behaviour of phyllodes tumours is difficult in the individual case. In the 4th edition, some progress has been made in prioritisation and weighting of histological parameters that can potentially estimate probability of recurrence. The WHO Working Group advocates leaning towards a diagnosis of fibroadenoma in cases where there is histological uncertainty in distinction from a benign phyllodes tumour, or adopting the neutral term 'benign fibroepithelial neoplasm', as the clinical behaviour of fibroadenoma overlaps with that of benign phyllodes tumour. The 3rd edition terminology of 'periductal stromal sarcoma' is revised to 'periductal stromal tumour', akin to the widespread consensus to avoid the use of the term 'cystosarcoma' in the context of phyllodes tumours.

Adenomioepitelioma de la mama: reporte de un caso / Adenomyoepithelioma of the breast: a case report

El adenomioepitelioma es un infrecuente tumor de la mama, conformado por una proliferación bifásica de células epiteliales y mioepiteliales. Presentamos las características clínicas y morfológicas de un caso de adenomioepitelioma benigno diagnosticado en una paciente de 34 años en la Unidad de Anatomía Patológica del Hospital Hernán Henríquez Aravena de Temuco.

Breast adenomyoepithelioma is a rare tumor, characterized bythe biphasic proliferation of epithelial and myoepithelial cells. We present clinical and morphological features of a case of benign adenomyoepithelioma diagnosed in a 34 year old patient in the Hernán Henríquez Aravena Hospital in Temuco.

Mioepitelioma benigno: presentación de un caso clínico / Benign myoepithelioma: presentation of a case report

Se presenta un caso de mioepitelioma benigno de glándulaparótida, el cual fue tratado mediante la lobectomía superficial de la glándula,con conservación del nervio facial. Se hace el diagnóstico diferencialcon otros tumores benignos como el adenoma pleomorfo, con el cual compartenuna clínica similar. También se destaca la importancia de un correctodiagnóstico anatomopatológico, en este caso haciendo diagnóstico diferencialcon los carcinomas epi-mioepiteliales(AU)

We present a case of benign myoepithelioma ofthe parotid gland, which was treated by superficial glandlobectomy along with facial nerve conservation. A differentialdiagnosis with other benign tumors with similar clinicalsigns such as pleomorphic adenoma is made. The importanceof a correct anatomopathologic diagnosis is also stressed,as is making a differential diagnosis with epi-myoepithelialcarcinomas(AU)

[Cystic myoepithelioma. A rare differential diagnosis of a cystic lesion of the parotid gland]. / Zystisches Myoepitheliom. Seltene Differenzialdiagnose einer zystischen Raumforderung der Glandula parotis.

By sonography, we found a sharply demarcated tumor with cystic areas in the parotid gland of a 41 year old male, indicating Warthin's tumor. Subtotal parotidectomy was performed. Microscopy showed an encapsulated tumor with myoepithelial cells and, in particular, central pseudocysts. Immunohistochemically, the tumor cells expressed cytokeratin 5/6 and S-100 protein as well as smooth muscle-actin. These features led to the diagnosis of a cystic myoepithelioma. Histopathologically, several different lesions of the salivary glands should be considered in the differential diagnosis of myoepithelioma, especially of this hitherto unique case in the parotid gland. The differential diagnoses are reviewed and discussed. Treatment is by surgical resection. Because of the tendency of myoepitheliomas to recur and to malignant transformation, tumor-free margins are recommended.

Myoepithelial tumors of soft tissue: a clinicopathologic and immunohistochemical study of 101 cases with evaluation of prognostic parameters.

Myoepitheliomas and mixed tumors were only recently recognized to occur primarily in soft tissue, and only small case numbers have been described. To characterize these tumors further and to evaluate prognostic parameters, 101 myoepithelial tumors of soft tissue were retrieved from the authors' consult files. Hematoxylin and eosin sections were reexamined, immunohistochemistry was performed, and clinical details were obtained from referring physicians. Fifty-three patients were male and 48 female (mean age 38 years; range 3-83 years). Tumor size ranged from 0.7 to 20 cm (mean 4.7 cm). Most tumors arose in the extremities and limb girdles: 41 in the lower limbs, 35 in the upper limbs, 15 in the head and neck, and 10 in the trunk. Fifty-four tumors were situated in subcutis and 37 in deep soft tissue (depth unstated in 10). Most cases were grossly well circumscribed; 43 showed microscopically infiltrative margins. Histologically, most tumors were lobulated, composed of cords or nests of epithelioid, ovoid, or spindled cells with a variably reticular architecture and a chondromyxoid or collagenous/hyalinized stroma. Eight cases showed a predominantly solid proliferation of spindled or plasmacytoid cells; 17 demonstrated ductular differentiation (mixed tumors). Cartilage was present in 6 cases, 6 contained bone, and 4 others contained both. Mitoses ranged from 0 to 68 per 10 high power fields (mean 4.7 per 10 high power fields). Tumors with benign cytomorphology or mild cytologic atypia (low-grade) were classified as myoepithelioma or mixed tumor, whereas tumors with moderate to severe atypia (high-grade) were classified as myoepithelial carcinoma (epithelioid or spindled cells with vesicular or coarse chromatin, prominent, often large nucleoli, or nuclear pleomorphism) or malignant mixed tumor (cytologically malignant cartilage or bone). Sixty-one cases were myoepitheliomas or mixed tumors, and 40 were myoepithelial carcinomas or malignant mixed tumors. By immunohistochemistry, all cases with available material were reactive for epithelial markers (keratins and/or epithelial membrane antigen): 90 of 97 (93%) expressed keratins (most often AE1/AE3 or PAN-K), 84 of 97 (87%) S-100 protein, 44 of 51 (86%) calponin, 52 of 83 (63%) epithelial membrane antigen, 40 of 87 (46%) glial fibrillary acidic protein, 27 of 75 (36%) smooth muscle actin, 15 of 66 (23%) p63, and 7 of 51 (14%) desmin. Follow-up was available for 64 patients. Among 33 cases with benign or low-grade cytology (mean follow-up 36 months; range 4-168 months), 6 recurred locally (18%) and none metastasized. No clinical or histologic features correlated with recurrence. Among 31 cytologically malignant cases (mean follow-up 50 months; range 4-252 months), 13 recurred locally (42%) and 10 metastasized (32%); so far, 4 patients have died of metastatic tumor. This study expands the spectrum of myoepithelial tumors of soft tissue to include myoepithelial carcinomas and malignant mixed tumors, which pursue an aggressive clinical course. Although the majority of morphologically benign or low-grade myoepithelial neoplasms of soft tissue behave in a benign fashion, there is an approximate 20% risk for local recurrence.

Carcinoma basocelular con diferenciación mioepitelial / Basall cell carcinoma with myoepithelial differentiation

Presentamos un nuevo caso de carcinoma basocelular con diferenciación micepitelial en un varón de 71 años. La tumoración, de 2,5 cm, estaba localizada en el ala nasal izquierda. Se trataba de un carcinoma basocelular típico que infiltraba en profundidad, alcanzando el tejido muscular. En algunas áreas del tumor el citoplasma de las células neoplásicas se hacía homogéneo y eosinofilico, desplazando el núcleo a la periferia. Estas células eran idénticas a las llamadas células hialinas descritas en tumores mixtos y mioepiteliomas de glándula salival y piel. En el estudio inmunohistoquímico presentaban una franca positividad para la actína muscular específica (HHF35) y más débil para la desmína. Ultraestructuralmente la eosinofilia citoplasmática estaba determinada por la presencia de abundantes filamentos finos de tipo actína que desplazaban los escasos tonofilamentos a la periferia. Estas células cumplían todos los criterios para ser etiquetadas como mioepiteliales. En la literatura sólo se han descrito siete casos de carcinoma basocelular con esta peculiar diferenciación (AU)

Salivary gland basal cell and canalicular adenomas: immunohistochemical demonstration of myoepithelial cell participation and morphogenetic considerations.

OBJECTIVE: To evaluate cellular composition of salivary gland adenomas using 3 monoclonal antibodies that recognize a smooth muscle phenotype confirmed to be sensitive for myoepithelial differentiation. DESIGN: Immunohistochemical evaluation of 25 salivary gland basal cell and canalicular adenomas. SETTING: Archival pathology material from the files of Henry Ford Hospital, Detroit, Mich, and the University of California at San Francisco. RESULTS: All basal cell adenoma variants exhibit some degree of myoepithelial cell participation with periductal, epithelioid, and spindled (stromal-like) morphologic structures. Only the canalicular adenomas, even if mixed with trabecular and solid patterns, are devoid of staining with these 3 antibodies, suggesting an adenoma composed exclusively of ductal luminal cells. CONCLUSIONS: There is an overlapping histomorphologic and common cellular composition of the basal cell adenoma variants with other recognized adenomas, such as pleomorphic adenoma and myoepithelioma. Relative differentiation toward 3 cell phenotypes (ductal luminal, basal, and myoepithelial) and the character of extracellular matrix production in varying proportions by the neoplastic myoepithelial cells distinguishes the spectrum of salivary gland adenomas identified in current classification schemes.

So-called neoplastic myoepithelial cells in chondroid syringomas/mixed tumors of the skin: their subtypes and immunohistochemical analysis.

An immunohistochemical study of nine cases of chondroid syringomas/mixed tumors of the skin was performed to elucidate the nature of the so-called neoplastic myoepithelial cells (NMEC) in tumor tissues. These nine tumors contained NMEC of considerable variability in number from one tumor to another. These NMEC were classified into three types: (i) hyaline cells (plasmacytoid cells); (ii) spindle NMEC; and (iii) polyhedral cells. They showed different immunostaining patterns, as the following describes. Cytokeratin 14 was positive in most of the spindle NMEC and a large number of the polyhedral cells, and in a small number of the hyaline cells. Concerning low molecular weight cytokeratins, most of the hyaline cells showed immunoreactivity, whereas they were negative in many of the spindle NMEC and were expressed only in a small number of the polyhedral cells. alpha-Smooth muscle actin and muscle-specific actin were positive in the spindle NMEC but negative in any of the hyaline cells and polyhedral cells. These findings strongly indicate that the hyaline cells and the spindle NMEC are of the simple epithelial and myoepithelial types, respectively. The findings also suggest that the polyhedral cells show differentiation toward basal cells of the sweat gland dermal ducts or myoepithelial cells.

Expression of the adenocarcinoma-related antigen recognized by monoclonal antibody 44-3A6 in salivary gland neoplasias.

The monoclonal antibody 44-3A6 detects a cell-surface protein that has been shown to be a useful marker in distinguishing adenocarcinomas from other histologic tumor types in a variety of tissues. The objective of this study was to determine whether 44-3A6 could be used as a tool in the classification of salivary gland neoplasms. These complex tumors share overlapping pathologic features but distinct clinical outcomes. This study used 44-3A6 to immunohistochemically describe the pattern and frequency of this antigen in salivary gland neoplasms. Formalin-fixed, paraffin-embedded tissue sections of 22 benign and 26 malignant salivary tumors were evaluated. The patient population consisted of 25 (52.1%) women and 23 (47.9%) men selected from archival pathology files to reflect a range of salivary gland diseases. Normal surrounding salivary glands were found to have intense focal staining almost exclusively localized to ductal luminal cells. There was little staining of either myoepithelial or acinar cells. A wide spectrum of expression was found between and within tumor types, but a trend toward more expression of this antigen with decreasing differentiation was seen. A significant increase in staining was also seen in those tumors with ductal differentiation (n = 41) as opposed to those with predominantly acinar (i.e., acinic cell carcinoma) or myoepithelial (i.e., myoepithelioma; n = 8) differentiation (2.6 vs. 1.3, p < 0.05). No correlation was found between staining intensity and facial paralysis, pain, skin involvement, TNM stage, residual disease, or disease-free or total survival. Therefore this antigen appears to designate a duct luminal phenotype in normal and neoplastic salivary tissues.

Myoepithelioma--new concepts of histology and classification: a light and electron microscopic study.

Based on histological, immunohistochemical, and ultrastructural studies, it is now apparent that the modified myoepithelial cell component of pleomorphic adenomas has a considerable range of cytological features. We reasoned that myoepitheliomas could be tumors with a similar spectrum of neoplastic myoepithelium but lacking the ductal element displayed in pleomorphic adenomas. A review of available salivary gland tumors identified 40 examples based on this definition. Architecturally, these myoepitheliomas displayed either nonmyxoid (solid), myxoid (pleomorphic adenoma-like), reticular (canalicularlike), or mixed growth patterns, while cytologically the lesions were composed of spindle-type (32.5%), hyaline-type (7.5%), epithelial-type (45.0%), clear-type (2.5%), or mixed-type (12.5%) tumor cells. Electron microscopy was carried out on eight examples and detailed immunohistochemistry on two methanol-fixed cases. As a result of the current review of myoepitheliomas and the description of similar lesions in the literature, it is our contention that salivary gland myoepitheliomas are not as rare as has been purported.