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Tumors of the salivary glands are rare and have various histo-pathological subtypes. The overall incidence is 2.5–3 per 100,000 patients per year. Myoepithelioma of the parotid gland is very rare with an incidence of only 1–1.5% among all salivary gland tumors. The diagnostic criteria for benign myoepithelioma were laid down on the basis of the work of Barnes and Sciubba. A 30-year-old lady presented to our university with a mass slowly increasing in size. There were no aggravating and/or relieving factors found. On examination a 3 × 3 cm diffuse swelling was found around the right pre auricular area. Fine Needle Aspiration Cytology (FNAC) was performed. The findings were suggestive of a pleomorphic adenoma. The patient underwent a right sided superficial parotidectomy to remove the tumor. The final histopathology report revealed the tumor to be a myoepithelioma. Myoepithelioma is a benign salivary gland neoplasm formed almost entirely of myoepithelial cells arranged in a sheet, island or cord-like fashion. On CT scans, it presents as a well-circumscribed homogenous lesion with lobulated or smooth margins. Myoepitheliomas may also have nodules that enhance under contrast and areas of linear bands that do not. The recommended treatment for a myoepithelioma is complete surgical excision with wide margins. It has a very low recurrence rate compared to the 15–18% recurrence rate for pleomorphic adenomas. Utilization of immunohistochemical staining is of utmost importance in suspected myoepithelioma cases to ensure proper treatment and follow-up. Myoepitheliomas are rare tumors which must be included in the differential if a patient presents with a tumor of characteristics similar to those described above. Immunohistochemistry and electron microscopy are useful tools for the diagnosis of myoepitheliomas.

Myoepithelial carcinoma (MECA) is a rare salivary gland (SG) neoplasm (0.1–0.45% of all SG tumors) that often presents with bland cytomorphology and can be misclassified as cellular pleomorphic adenoma (PA) or myoepithelioma. This is particularly challenging in MECA ex-PA cases, especially if tumor shows minimal to no capsular invasion. We report a rare case of a 76-year-old female; history of left superficial parotidectomy with diagnosis (outside hospital) of cellular PA, who re-presented 9 months post surgery with enlarging left parotid mass, neck lymphadenopathy and facial nerve deficits. FNAB of parotid and neck lymph node revealed cellular aspirates with loosely cohesive clusters of myoepithelial cells with occasional chondromyxoid stroma. Prior resection slides were reviewed, and diagnosis of MECA ex-PA was made. Patient underwent left radical parotidectomy, selective neck dissection, with facial nerve sacrifice (due to extensive encasing by tumor). Histology showed a multinodular tumor with pushing borders, zonal arrangement comprising of a hypocellular, necrotic/myxoid center, and a peripheral rim of myoepithelial cells, confirmed by positive S100, and p63. Tumor extensively infiltrated peri parotid soft tissues with multiple foci of lymphovascular and perineural invasion; and metastatic neck lymph nodes. Next generation sequencing revealed a novel TERT promoter mutation (c.-124C > T), not usually described in SG neoplasms. Further, PD-L1 immunohistochemistry showed positive expression, making patient eligible for anti-PDL-1 immunotherapy. This case highlights importance of recognizing the subtle malignant features of MECA in distinguishing it from benign mimics like PA. In addition, presence of TERT mutation opens a new arena for future research to explore potential treatment targets.

SMARCB1 biallelic inactivation resulting in SMARCB1/INI1 deficiency drives a wide range of malignancies, including many mesenchymal tumors. However, the specific types of SMARCB1 alterations and spectrum of cooperating mutations among various types of sarcomas has not been well investigated. We profiled SMARCB1 genetic alterations by targeted DNA sequencing and fluorescence in situ hybridization (FISH) in a large cohort of 118 soft tissue and bone tumors, including SMARCB1-deficient sarcomas (78, 66%): epithelioid sarcomas, epithelioid peripheral nerve sheath tumors, poorly differentiated chordomas, malignant rhabdoid tumors, and soft tissue myoepithelial tumors, as well as non-SMARCB1-deficient sarcomas (40, 34%) with various SMARCB1 genetic alterations (mutations, copy number alterations). SMARCB1 loss by immunohistochemistry was present in 94% SMARCB1 pathogenic cases. By combined sequencing and FISH assays, 80% of SMARCB1-deficient tumors harbored homozygous (biallelic) SMARCB1 loss, while 14% demonstrated heterozygous SMARCB1 loss-of-function (LOF) alterations, and 6% showed no demonstrable SMARCB1 alterations. FISH and sequencing were concordant in the ability to detect SMARCB1 loss in 48% of cases. Epithelioid sarcomas most commonly (75%) harbored homozygous deletions, while a subset showed focal intragenic deletions or LOF mutations (nonsense, frameshift). In contrast, most soft tissue myoepithelial tumors (83%) harbored SMARCB1 nonsense point mutations without copy number losses. Additionally, clinically significant, recurrent co-occurring genetic events were rare regardless of histotype. By sequencing, extended 22q copy number loss in genes flanking the SMARCB1 locus (22q11.23) occurred in one-third of epithelioid sarcomas and the majority of poorly differentiated chordomas. Poorly differentiated chordomas and soft tissue myoepithelial tumors showed significantly worse overall and disease-free survival compared to epithelioid sarcomas. Overall, SMARCB1 LOF alterations predominate and account for SMARCB1 protein loss in most cases: majority being biallelic but a subset were heterozygous. In contrast, SMARCB1 alterations of uncertain significance can be seen in diverse sarcomas types and does not indicate a SMARCB1-deficient entity.

The RREB1::MRTFB (former RREB1::MKL2) fusion characterizes ectomesenchymal chondromyxoid tumors (EMCMT) of the tongue. Only five molecularly confirmed extra-glossal EMCMT cases have been reported recently; all occurring at head and neck or mediastinal sites. We herein describe five new cases including the first two extracranial/extrathoracic cases. The tumors occurred in three male and two female patients with an age ranging from 18 to 61 years (median, 28). Three tumors were located in the head and neck (jaw, parapharyngeal space, and nasopharyngeal wall) and two in the soft tissue (inguinal and presacral). The tumor size ranged from 3.3 to 20 cm (median, 7). Treatment was surgical without adjuvant treatment in all cases. Two cases were disease-free at 5 and 17 months; other cases were lost to follow-up. Histologically, the soft tissue cases shared a predominant fibromyxoid appearance, but with variable cytoarchitectural pattern (cellular perineurioma-like whorls and storiform pattern in one case and large polygonal granular cells embedded within a chondromyxoid stroma in the other). Two tumors (inguinal and parapharyngeal) showed spindled to ovoid and round cells with a moderately to highly cellular nondescript pattern. One sinonasal tumor closely mimicked nasal chondromesenchymal hamartoma (NCMH). Mitotic activity was low (0-5 mitoses/10 hpfs). Immunohistochemical findings were heterogeneous with variable expression of S100 (2/5), EMA (2/3), CD34 (1/4), desmin (1/4), and GFAP (1/3). Targeted RNA sequencing revealed the same RREB1::MRTFB fusion in all cases, with exon 8 of RREB1 being fused to exon 11 of MRTFB. This study expands the topographic spectrum of RREB1::MRTFB fusion-positive mesenchymal neoplasms, highlighting a significant morphological and phenotypic diversity. Overall, RREB1::MRTFB-rearranged neoplasms seem to fall into two subcategories: tumors with lobulated, chondroid, or myxochondroid epithelioid morphology (Cases 2 and 3) and those with more undifferentiated hypercellular spindle cell phenotype (Cases 1, 4, and 5). Involvement of extracranial/extrathoracic sites and the NCMH-like pattern are novel. The biology of these likely indolent or benign tumors remains to be verified in the future.

Myoepithelial carcinomas (MECs) of soft tissue are rare and aggressive tumors affecting young adults and children, but their molecular landscape has not been comprehensively explored through genome sequencing. Here, we present the whole-exome sequencing (WES), whole-genome sequencing (WGS), and RNA sequencing findings of two MECs. Patients 1 and 2 (P1, P2), both male, were diagnosed at 27 and 37 yr of age, respectively, with shoulder (P1) and inguinal (P2) soft tissue tumors. Both patients developed metastatic disease, and P2 died of disease. P1 tumor showed a rhabdoid cytomorphology and a complete loss of INI1 (SMARCB1) expression, associated with a homozygousSMARCB1deletion. The tumor from P2 showed a clear cell/small cell morphology, retained INI1 expression and strong S100 positivity. By WES and WGS, tumors from both patients displayed low tumor mutation burdens, and no targetable alterations in cancer genes were detected. P2's tumor harbored anEWSR1::KLF15rearrangement, whereas the tumor from P1 showed a novelASCC2::GGNBP2fusion. WGS evidenced a complex genomic event involving mainly Chromosomes 17 and 22 in the tumor from P1, which was consistent with chromoplexy. These findings are consistent with previous reports ofEWSR1rearrangements (50% of cases) in MECs and provide a genetic basis for the loss of SMARCB1 protein expression observed through immunohistochemistry in 10% of 40% of MEC cases. The lack of additional driver mutations in these tumors supports the hypothesis that these alterations are the key molecular events in MEC evolution. Furthermore, the presence of complex structural variant patterns, invisible to WES, highlights the novel biological insights that can be gained through the application of WGS to rare cancers.

SMARCB1 (INI-1)-deficient vulvar neoplasms comprise a group of rare tumours that include epithelioid sarcoma (ES), myoepithelial carcinoma (MEC), the recently described myoepithelioma-like tumour of the vulvar region (MELTVR), and sarcomas that are difficult to classify. It has been suggested that so-called vulvar yolk sac tumours (YST) may represent morphologic variants of SMARCB1-deficient tumours; thus, we investigated the immunoreactivity of germ cell markers in SMARCB1-deficient vulvar neoplasms.Ten SMARCB1-deficient vulvar neoplasms were stained with germ cell tumour markers (SALL4, glypican-3, OCT3/4, and AFP) and re-reviewed for morphologic features. The tumours occurred in adult females (median age 41 years) and included ES (n = 7), MELTVR (n = 2), and MEC (n = 1). All cases showed loss of SMARCB1 expression. Four cases (40%) were focally positive for SALL4 in areas with morphology of typical-appearing ES. One of these cases also showed focal staining for OCT3/4. One ES showed a transition from typical-appearing ES to YST-like morphology, with diffuse expression of SALL4 and glypican-3, and focal expression of AFP, in these latter areas. All other tested cases were negative for AFP.Our study reveals that SALL4, glypican-3, and OCT3/4 are positive in a subset of SMARCB1-deficient vulvar neoplasms, which may pose a diagnostic challenge and result in consideration of a germ cell tumour. We also highlight a case with transition from ES to YST-like morphology, lending further support that YSTs of the vulva are somatically derived SMARCB1-deficient neoplasms and do not represent true germ-cell neoplasia.

Myoepithelial carcinoma, also known as malignant myoepithelioma, is considered an extremely rare (0.45–1%) malignant salivary gland neoplasm. Approximately 100 cases have been reported in the English-language literature on myoepithelial carcinoma. The majority of the myoepitheliomas described in the literature have been benign, and the malignant counterpart is considered rare (

Myoepithelial carcinoma (MECA) may overlap histologically with other salivary gland neoplasms, especially pleomorphic adenoma. MECA is characterized by cellular, uniform growth of myoepithelial cells and multinodular expansile invasive pattern with zonal cellular distribution. It may arise de novo or in association with pleomorphic adenoma (myoepithelial carcinoma ex pleomorphic adenoma). By immunohistochemistry, MECA is positive for cytokeratins and at least one of the myoepithelial markers, including S100. PLAG1 fusion is the most common genetic alteration. Carcinoma ex pleomorphic adenoma and necrosis correlate with worse clinical outcome in MECA, and necrosis can be used to stratify MECA as high grade.

Highlights • Knowledge about tracheal tumors is important to avoid misdiagnosis. • Awareness of the option of tracheal resection is necessary to avoid suboptimal treatment recommendations. • Microcystic reticular schwannoma is a rare variant of a neurogenic tumor and may occur in the trachea. • Complete resection should be considered even without clear preoperative tumor histology. • Tracheal segmental resection is a safe procedure and treatment of choice for resectable, intra-/transmural tumors causing tracheal obstruction., Introduction and importance Diagnosis and treatment of rare diseases are challenging because experience and evidence are limited. Primary tracheal tumors have a low prevalence but awareness of these is important to avoid misdiagnoses. We present a first case of a tracheal microcystic reticular schwannoma in which diagnosis and treatment recommendations were revised several times resulting in months of anxious uncertainty for the patient before complete resection and extensive histopathologic examination were performed. Case presentation A 65-year old woman complained about coughing and cervical pain. Tomographies revealed a tumor of the dorsolateral trachea. After repeated biopsies pathologists and tumorboards in different hospitals could not agree on diagnosis or treatment recommendation, so the impatient patient opted for a complete resection for definite treatment. Clinical discussion Neoplasms of the posterior mediastinum are mainly neurogenic. In rare cases they may originate in the trachea and can be difficult to differentiate from other tumor entities if only biopsies are available. Although the preoperative diagnosis was unclear, tracheal resection was performed successfully. The differential diagnoses of soft tissue sarcoma or myoepithelioma were discarded and a benign, microcystic, reticular schwannoma was confirmed by international reference pathologists. Conclusion Microcystic, reticular schwannoma is a rare variant and may occur in the trachea. Diagnosis of such rare neoplasms can be difficult, resulting in delayed or suboptimal treatment. Often biopsies are not sufficient to reach a definite diagnosis. But even without preoperative histology, tracheal resection is a safe and feasible option for definitive treatment with very low recurrence rates.

У статті описано випадок рідкісної пухлини молочної залози, що на етапі передопераційної діагностики трактувалася як підозра на рак. Тільки імуногістохімічне дослідження дозволило встановити природу та доброякісний характер новоутворення і коректний діагноз.

Myoepithelial tumors are rare neoplasms that primarily occur in the salivary gland but over the last decade have also been described in other locations, including soft tissue. Myoepithelial carcinoma of soft tissue has shown to have a recurrence rate of 39-42% and distant metastases in 32-53% of patients. The only known predictor of malignancy in soft tissue myoepithelial tumors described is cytologic atypia. There are no other validated criteria for differentiating benign and malignant tumors, neither for grading nor for standard of care for these tumor types. Herein, we present a case of myoepithelial carcinoma of inguinal soft tissue in a 37-year male. We also describe the molecular and previously sparingly described detailed electron microscopic features of this case.

Myoepithelial neoplasms of soft tissue are rare tumors with clinical, morphological, immunohistochemical, and genetic heterogeneity. The morphological spectrum of these tumors is broad, and the diagnosis often requires immunostaining to confirm myoepithelial differentiation. Rarely, tumors show a morphology that is typical for myoepithelial neoplasms, while the immunophenotype fails to confirm myoepithelial differentiation. For such lesions, the term “myoepithelioma-like” tumor was introduced. Recently, two cases of myoepithelioma-like tumors of the hands and one case of the foot were described with previously never reported OGT-FOXO gene fusions. Here, we report a 50-year-old woman, with a myoepithelial-like tumor localized in the soft tissue of the forearm and carrying a OGT-FOXO1 fusion gene. Our findings extend the spectrum of mesenchymal tumors involving members of the FOXO family of transcription factors and point to the existence of a family of soft tissue tumors that carry the gene fusion of the OGT-FOXO family.

Carcinoma ex pleomorphic adenoma (Ca ex PA) is a rare type of malignant salivary gland tumor. Myoepithelial carcinoma (MEC) as the malignant component in Ca ex PA is an even rarer occurrence. Preoperative pathological diagnosis of Ca ex PA often goes unnoticed in many cases as they may be clinically indolent and the malignant component may not be picked up on fine-needle aspiration cytology. However, features such as rapid growth, recurrent tumor, and pain point toward a malignant transformation. We present a case of a 40-year-old female who presented with a history of recurrent swelling over parotid region with cytological diagnosis of pleomorphic adenoma, which on excision was reported as Ca ex PA with MEC being the malignant constituent. Till date, few cases of MEC arising from PA have been reported. It presents as a diagnostic challenge to both clinicians and pathologists alike; prognosis is still not clear due to few number of cases and lack of follow-up in most of them.

Background Salivary cancer is rare and comprises a variety of histological subtypes and clinical behaviors. There is no agreed method of estimating the risk of occult metastasis or managing the clinically N0 neck.Sentinel node biopsy (SNB) may offer a solution but previous studies have not produced a reliable imaging protocol. This study uses novel technology and trial methodology to develop a reliable SNB technique, with primary aim to identify peri-and intraglandular sentinel nodes. Methods IDEAL framework was used to undertake SNB in clinically node negative salivary gland cancer. Patients with cT1-2 N0 salivary cancer were eligible. Lymphoscintigraphy was undertaken using Tc-99 m labelled nanocoll. Injection technique as well as adjunctive use of freehand SPECT (fhSPECT), near-infrared (NIR) fluorescence imaging, and navigation-guided surgery were used and optimisied during the study protocol. Results 10 patients were recruited. Initial protocol of peritumoural injection of Tc99 m nanocoll showed poor image resolution. Subsequent adjustment to single intratumoural injection allowed identification of intraglandular sentinel nodes. Fh/SPECT and NIR fluorescence imaging found intraglandular lymph nodes otherwise not recognizable to the naked eye. In two cases occult lymph node metastasis were identified. Conclusion This study has shown the IDEAL framework is vital in allowing iterative changes in surgical protocol in the light of experience. This study has produced a reliable method for detection of sentinel nodes, in particular the ability to identify intra- and periglandular nodes with diagnosis of occult metastatic deposits and no false negative results. Our protocol can be readily transferred in to larger scale studies.

Cutaneous myoepithelial neoplasms are a heterogenous group of neoplasms with mixed tumors typically affecting the head and myoepitheliomas showing a predilection for the extremities. Their malignant counterparts, myoepithelial carcinoma, and malignant mixed tumor are exceptionally rare in the skin, and the morphologic criteria for malignancy are only poorly defined. The aim of the present study was to characterize the clinicopathologic features of myoepithelial neoplasms presenting on acral skin. The clinical and histopathologic features of 11 tumors were recorded, and follow-up was obtained. Immunohistochemistry was performed for S100, SOX10, glial fibrillary acidic protein, keratins, epithelial membrane antigen, p63, p40, smooth muscle actin, desmin, and PLAG1. The tumors mainly affected the feet of adults (range: 26 to 78 y; median: 47 y) with a predilection for the great toe and a male predominance of 1.8:1. Most tumors (91%) displayed a lobular architecture composed of solid and nested growth of epithelioid cells with plasmacytoid features in a myxoid or angiomatous stroma. Scattered cytologic atypia and rare duct differentiation were frequently noted. Three tumors with confluent cytologic atypia, infiltrative growth, and lymphovascular invasion were classified as malignant. By immunohistochemistry, the tumors were positive for S100, SOX10, keratins AE1/AE3, CK5/6 and CK7, and PLAG1. Local recurrence and bilateral pulmonary metastasis were observed in a patient presenting with a histopathologically benign-appearing tumor. Two patients with malignant tumors experienced local recurrences, and 1 developed metastasis to soft tissue, lung, and mediastinal lymph nodes. All patients are currently alive, all but 1 with no evidence of disease after a median follow-up interval of 96 months (range: 2 to 360 mo). In conclusion, acral myoepithelial neoplasms show distinctive and reproducible histopathologic and immunohistochemical features. They are best regarded as a distinctive subset of mixed tumors with features reminiscent of their salivary gland counterparts. While most tumors pursue a benign disease course, histopathologic features appear to be a poor indicator of prognosis.

BACKGROUND Breast adenomyoepithelioma is a rare benign breast tumor characterized by a biphasic proliferation of epithelial and myoepithelial cells with variable clinical and diagnostic features. Establishing the diagnosis, determining optimal therapy, and predicting outcome are problematic because of the rarity of this entity. There have been only 2 large series of adenomyoepitheliomas of the breast, reported by Tavassoli and Rosen, which included 27 and 18 patients, respectively. In this report, we present 3 cases of breast adenomyoepithelioma. CASE REPORT Herein, we report 3 cases of breast adenomyoepithelioma. The first case is of a 64-year-old woman who was found to have right breast microcalcification on a screening mammogram. The second case is of a 74-year-old woman who had a right breast mass. These 2 patients were managed by wide local excision. Postoperative microscopic examination revealed adenomyoepithelioma. The third case is of a 49-year-old woman with bilateral saline breast implants who presented with a left breast mass. A core needle biopsy was done and revealed adenomyoepithelioma associated with usual ductal hyperplasia and ductal carcinoma in situ. CONCLUSIONS Breast adenomyoepithelioma is a rare condition that can pose diagnostic challenges due to variable imaging presentations, necessitating percutaneous core biopsy for initial diagnosis. Correct diagnosis is usually possible only on excisional biopsy and confirmed by demonstrating the biphasic nature of the tumor by IHC. Clinical suspicion coupled with utilizing both radiological and histopathological facilities can aid in the accurate diagnosis and management. For the most part, they are considered to be benign, but they can locally recur.

Myoepithelial carcinoma (MEC) of soft tissue, also known as malignant myoepithelial tumor, is an uncommon malignancy. Cytologic diagnosis of this entity is challenging due to its rarity and heterogeneous morphology. We report a case of MEC in a 22-year-old man, who presented with a 6.5 cm soft tissue mass on his right distal forearm that has been enlarging over the past 3 months. Ultrasound-guided fine-needle aspiration (FNA) revealed abundant isolated neoplastic cells ranging from spindled cells to epithelioid and plasmacytoid morphology in a myxoid background. These cells showed moderate cytologic atypia characterized by high-nuclear/cytoplasmic ratio, irregular nuclear contours, and prominent nucleoli. The cytoplasm varied from dense to vacuolated and occasionally rhabdoid with intracytoplasmic inclusions. Scattered bi- and multinucleated cells were identified. A diagnosis of high-grade malignancy was made with the differential diagnosis including rhabdomyosarcoma and melanoma. A subsequent core biopsy of the tumor showed immunoreactivity for pan-cytokeratins, calponin, p63, and smooth muscle actin. INI-1 was lost. SOX-10 and Melan-A were negative. Molecular studies showed loss of SMARCB1 (INI-1) and CDKN2A. Gene fusion studies did not detect any fusion. A diagnosis of soft tissue MEC was made which is a challenge on FNA due to several cytologic mimickers including rhabdomyosarcoma, epithelioid sarcoma, extrarenal rhabdoid tumor, extra-axial chordoma and melanoma. Recognition of the biphasic cell population in a myxoid background and a battery of immunohistochemical stains are crucial for accurate diagnosis.

Myoepithelial tumors (MET) constitute a group of neoplasms with a variety of morphologic, immunophenotypic, and molecular features. Approximately half of MET of soft tissue harbor EWSR1 gene rearrangements with a subset showing EWSR1-POU5F1 fusions and demonstrating distinctive tendency towards aggressive behavior in children. Histologically, EWSR1-POU5F1-positive MET typically show clear-cell morphology with malignant features including marked pleomorphism and atypical mitotic figures. The cytomorphology of these tumors has not been well characterized. Reported here are the cytomorphologic features of two cases of EWSR1-POUF1-positive MET with histology correlation.

Myoepithelial carcinoma of salivary glands is an underrecognized and challenging entity with a broad morphologic spectrum, including an EWSR1-rearranged clear cell variant. Myoepithelial carcinoma is generally aggressive with largely unknown genetic features. A retrospective review of Salivary Gland Tumor Registry in Pilsen searching for the key words "clear cell myoepithelial carcinoma," "hyalinizing clear cell," and "clear cell malignant myoepithelioma" yielded 94 clear cell myoepithelial carcinomas (CCMCs) for molecular analysis of EWSR1 rearrangement using fluorescence in situ hybridization (FISH). Tumors positive for EWSR1 gene rearrangement were tested by next-generation sequencing (NGS) using fusion-detecting panels. NGS results were confirmed by reverse-transcription polymerase chain reaction or by FISH. Twenty-six tumors originally diagnosed as CCMC (26/94, 27.6%) revealed split signals for EWSR1 by FISH. Six of these tumors (6/26, 23%) displayed amplification of the EWSR1 locus. Fifteen cases were analyzable by NGS, whereas 9 were not, and tissue was not available in 2 cases. None of the CCMCs with EWSR1 rearrangements detected by FISH had an EWSR1 fusion transcript. Fusion transcripts were detected in 6 cases (6/15, 40%), including LIFR-PLAG1 and CTNNB1-PLAG1, in 2 cases each, and CHCHD7-PLAG1 and EWSR1-ATF1 fusions were identified in 1 case each. Seven cases, including those with PLAG1 fusion, were positive for PLAG1 rearrangement by FISH, with notable exception of CHCHD7-PLAG1, which is an inversion not detectable by FISH. One single case with EWSR1-ATF1 fusion in NGS showed ATF1 gene rearrangement by FISH and was reclassified as clear cell carcinoma (CCC). In addition, another 4 cases revealed ATF1 rearrangement by FISH and were reclassified as CCC as well. Moreover, 12/68 (17%) CCMCs with intact EWSR1 gene were selected randomly and analyzed by NGS. PLAG1 fusions were found in 5 cases (5/12, 41.6%) with LIFR (2 cases), FGFR1 (2 cases), and CTNNB1 (1 case) as partner genes. Overall, PLAG1 gene rearrangements were detected in 10/38 (26%) tested cases. None of the tumors had SMARCB1 loss by immunohistochemistry as a possible explanation for the EWSR1 abnormalities in FISH. Novel findings in our NGS study suggest that EWSR1-FISH positive CCMC is a gene fusion-driven disease with frequent oncogenic PLAG1 fusions, including LIFR-PLAG1 and CTNNB1-PLAG1 in most cases. Productive EWSR1 fusions are found only in a minority of EWSR1-ATF1-rearranged cases, which were in part reclassifiable as CCCs. Detectable EWSR1-FISH abnormality in CCMCs without gene fusion perhaps represents a passenger mutation with minor or no oncologic effect.

We demonstrated the clinicopathological findings of 13 myoepitheliomas of soft tissue and bone (MESTBs) and two myoepithelioma-like tumors of the vulvar region (MELTVRs), focusing on the association between nuclear atypia and clinical course, and the utility of immunohistochemistry (IHC) of pleomorphic adenoma gene 1 (PLAG1) for the pathological diagnosis of these tumors. Of the 13 MESTBs, eight, one and four cases exhibited mild, moderate and severe nuclear atypia, respectively. Two cases with venous invasion showed severe nuclear atypia and both died of advanced disease. Two MELTVR cases showed moderate nuclear atypia and had no evidence of disease after surgery. On IHC, 12 of 13 (92.3%) MESTBs showed PLAG1 immunoreactivity and none of the MELTVRs expressed PLAG1. In addition, MELTVRs showed loss of INI1 expression. In contrast, all MESTBs retained INI1 expression. Fluorescence in situ hybridization detected EWSR1, FUS and PLAG1 rearrangement in 5 (38.5%), 0 (0%) and 2 (15.4%) of the 13 MESTBs, respectively. No EWSR1, FUS and PLAG1 rearrangement were observed in the METLVRs. In conclusion, MESTBs with both severe nuclear atypia and venous invasion would be indicative of malignant potential. PLAG1 might be a useful IHC marker in MESTB diagnosis.

Parachordoma is a rare soft tissue mixed tumor, associated with soft tissue myoepithelioma. It is typically growing slowly and considered less aggressive than other similar soft tissue tumors. However, it does recur sporadically, and on rare occasions, it has demonstrated the ability to metastasize. Although imaging is important, definitive diagnosis is achieved by histology, and it is typically treated by a wide local excision. We present the first reported case of a skull base parachordoma in a 15-year-old boy, managed with a wide local excision and with no signs of recurrence or metastases after 24 months of follow-up.

Background Primary myoepithelial carcinoma of the lung is a rare subtype in lung cancer. Comprehensive molecular profiling of myoepithelial carcinoma of the lung is absent, neither was clinical evidence of targeted therapy available for this disease. Therefore, the optimal treatment regimen of this tumor needs to be established. Case presentation Here we present a case of a 68-year-old patient with stage IVB primary myoepithelial carcinoma of the lung who harbored EGFR exon 19 deletion and KRAS mutation and underwent icotinib targeted therapy, achieving partial response (PR) with progression free survival (PFS) of 3 months. Conclusion To our knowledge, this study describes the first documented case of primary myoepithelial carcinoma lung cancer patient harboring EGFR exon 19 deletion and KRAS mutation, and showed clinical efficacy of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKI) treatment in this patient.

Myoepithelioma is a rare benign tumor of the salivary glands, in which the vast majority of neoplastic cells are myoepithelial. A rare microscopic finding in salivary gland tumors, including myoepitheliomas, is the presence of psammoma bodies (PBs), whose etiology and role in the tumors are uncertain. The objective of this study is to describe the unusual histopathologic findings, such as psammomas, of a large myopephelioma on the palate and the prosthetic restorative treatment performed after resection of the tumor. A 52-year-old woman was referred for evaluation of a tumor-like lesion, of smooth surface and normal mucosal color, measuring approximately 5 cm, on the left side hard palate, which had been identified 4 years earlier. The diagnostic hypothesis was a pleomorphic adenoma (PA), and an incisional biopsy was performed. After histopathologic analysis, a PA was suggested, and surgical resection of the tumor was performed. The histopathologic findings were compatible with myoepithelioma showing numerous calcified basophilic structures compatible with PB. Sixteen months after resection of the tumor, a removable maxillary obturator prosthesis was made because of the communication into oral and nasal cavity due from the surgical procedure. The treatment of choice for myoepithelioma is surgical excision with a nonlesional area margin. In the present report, the authors achieve good postoperative results without recurrences. After installation of the prosthesis, the patient had an excellent adaptation and acceptance, thus restoring her function and psychologic condition.

Ectomesenchymal chondromyxoid tumor is a rare neoplasm of uncertain histogenesis that typically occurs in the anterior dorsal tongue. Recent reports in the literature have described rare examples of gingival, palatal and tonsillar lesions. Histologically, ectomesenchymal chondromyxoid tumors are typically well-circumscribed, lacking overtly aggressive features. Herein we report a tumor arising in the right mandible that is morphologically and molecularly consistent with ectomesenchymal chondromyxoid tumor. This case furthers awareness of the extra-glossal distribution of this neoplasm; moreover, it suggests that a subset of these tumors have the potential for locally aggressive behaviour. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s12105-020-01169-5) contains supplementary material, which is available to authorized users.

Computed tomography (CT) and magnetic resonance imaging (MRI) can be useful for the evaluation of palatal lesions, and strain elastography (performed together with intraoral ultrasonography) is a relatively new sonographic imaging modality. This report describes 2 clinical cases in which strain elastography was used to assess palatal tumors in conjunction with intraoral ultrasonography, CT, and MRI. In the first case, diagnosed as a myoepithelioma, the strain was determined to be 0.000% (strain of normal tissue, 0.556%). In the second case, diagnosed as an adenoid cystic carcinoma, the determined strain was 0.000% (strain of normal tissue, 1.077%). Therefore, we conclude that intraoral strain elastography can be useful for evaluating palatal lesions.

Highlights • It is difficult to diagnose cellular variants of Sclerosing epithelioid sarcoma by fine needle aspiration. • If dense areas of tumor cells are collected by FNA, multiple myeloma and myoepithelioma can be different diagnosis. • MUC4 is a very useful immunological marker for diagnosis of Sclerosing epithelioid sarcoma., Introduction Sclerosing epithelioid sarcoma (SEF) is a rare fibroblastic sarcoma. It is classically composed of cords of epithelioid cells embedded in a hyalinized stroma; however, cases of cellular variants also exist. A cellular variants of SEF can mimic Plasmacytoma/Myeloma (PM) and myoepithelioma. Hence, accurate diagnosis of SEF is important for cytologists and pathologists. Presentation of case We present the case of a 75-year-old female patient diagnosed with a cellular variant of SEF occurring in the erector spinal muscle. Immunostaining of MUC4 and fluorescence in situ hybridization of EWSR1 (break-apart signal) were used for diagnosis. Conclusion The cellular variants of SEF presented diagnostic difficulties in fine needle aspiration. Moreover, it could not be distinguished from PM.

Feline mammary tumors are usually malignant and aggressive carcinomas. Most cases are simple monophasic carcinomas (1 epithelial population), and additional phenotyping is usually not needed. In this study, we describe 10 malignant mammary tumors from 9 female cats that had unusual histomorphology: they appeared biphasic, with 2 distinct cell populations. Initially, they were morphologically diagnosed as either carcinosarcoma (1/10) or malignant pleomorphic tumor (9/10) of the mammary gland, as the latter did not match any previously described histological subtype. Immunohistochemistry (IHC) was performed for pancytokeratin, cytokeratins 8 and 18, cytokeratin 14, cytokeratins 5 and 6, vimentin, p63, calponin, alpha-smooth muscle actin, Ki-67, ERBB2, estrogen receptor alpha, and progesterone receptor. In 7 of 10 cases, the biphasic nature was confirmed and, on the basis of the IHC results, they were classified as carcinoma and malignant myoepithelioma (4/10), ductal carcinoma (1/10), and carcinosarcoma (2/10). The other 3 of 10 cases were monophasic based on IHC. In the cases of carcinoma and malignant myoepithelioma, the malignant myoepithelial cells were 100% positive for vimentin (4/4) and variably positive for p63, calponin, and cytokeratins (4/4). These findings show that, although rare, biphasic mammary carcinomas do occur in cats. In dogs and humans, tumors composed of malignant epithelial and myoepithelial cells have a less aggressive behavior than certain simple carcinomas, and therefore, their identification might also be clinically significant in the cat.

Soft-tissue myoepithelioma (STM) is an extremely rare benign tumor with predominant occurrence in head, neck, pelvic girdle and limbs. These tumors lack specific clinical and morphological features and can easily be confused with more common neoplasms. It may lead to incorrect diagnosis and management. Here, we present a clinical case of a young man with retroperitoneal STM which simulated a pancreatic tumor and required a distal pancreatectomy. Performed literature review highlights current data about clinical, morphologic, immunohistochemical and genetic evaluation, treatment and prognosis of STM. J Med Cases. 2020;11(1):16-21 doi: https://doi.org/10.14740/jmc3407

Pulmonary epithelial-myoepithelial carcinoma is a very rare type of salivary gland lung tumor. No standard treatment plan yet. This article intends to analyze the clinical characteristics of pulmonary epithelial-myoepithelial carcinoma and discuss the diagnosis and treatment of pulmonary epithelial-myoepithelial carcinoma.The clinical data of a patient with pulmonary epithelial-myoepithelial carcinoma were analyzed and other relevant clinical literatures were reviewed.Epithelial cells immunohistochemically expressed cytokeratin and myoepithelial cells immunohistochemically expressed SMA and S-100. The next-generation sequencing was mainly HRAS gene mutation and the express of PD-L1 protein was negative.Most of the patients with Pulmonary epithelial-myoepithelial carcinoma have a good prognosis. Diagnosis mainly depends on microscopic examination and immunohistochemistry. The treatment of pulmonary epithelial-myoepithelial carcinoma is mainly surgical resection. The effect of radiotherapy and chemotherapy is not clear.【中文题目：肺上皮-肌上皮癌1例并文献复习】 【中文摘要：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。】 【中文关键词：肺上皮-肌上皮癌；免疫组化；诊断；治疗】.

ObjectiveRisk factors for salivary gland carcinoma are poorly understood. Although links between background radiation, smoking and obesity have been previously suggested, no studies have so far established any significant results. This study aimed to establish correlations between common environmental and lifestyle risk factors and different subtypes of salivary gland carcinoma.MethodA study of population data in Wales spanning 27 years was conducted; 2 national databases were used to identify 356 cases of primary salivary gland carcinoma over this period. Histological subtype of cancer and geographical location of each case was recorded. Public health data was used to establish radon levels, smoking, obesity and activity levels of populations in each geographical location. A population matched multivariate analysis of variance analysis was performed using histological subtype and risk factor data for each geographical location.ResultsA significantly higher incidence of mucoepidermoid cancer in populations with higher background radon levels (p =0.006), epithelial-myoepithelial cancer in populations with higher smoking levels (p =0.029) and adenoid cystic cancer in populations with higher obesity levels (p =0.028) was found.ConclusionTo the authors’ knowledge, this is the first study to establish significant links between background radiation, smoking and obesity with different subtypes of salivary gland carcinoma.