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Myoepithelioma is an exceptionally rare tumor, primarily arising in glandular tissues but occasionally found in soft tissues, including the hand. Its occurrence in the hand is particularly uncommon, presenting unique clinical challenges due to the limited number of documented cases and the unusual location. We conducted a literature review in June 2024, with the aim to evaluate the current understanding of hand myoepithelioma, recent diagnostic advances, treatment options, and the diverse presentations of this neoplasm. Articles confirmed that patients present with a painless, slow-growing mass in the hand, often misdiagnosed as more common soft tissue tumors like lipomas or fibromas. Imaging, particularly MRI and ultrasound, aids in assessing the tumor, but definitive diagnosis relies on histopathology, including immunophenotyping. Managing spindle cell myoepithelioma in the hand requires a multidisciplinary approach, with surgical excision being the primary treatment. Achieving clear margins is critical yet challenging due to the hand's complex anatomy. In some cases, adjuvant therapies such as radiation or chemotherapy may be necessary. The prognosis depends on factors like tumor size, location, and the success of surgical removal, with complete excision typically leading to a favorable outcome. [ABSTRACT FROM AUTHOR]

Ethmoid myoepithelial carcinoma is a rare tumor, with only 14 cases reported to date. This report discusses the largest tumor of this type ever recorded in the ethmoid region. The tumor caused extensive damage to facial structures, complicating treatment. The patient’s age and comorbidities increased the risk of intraoperative bleeding, presenting challenges to the complete removal of the tumor and the reconstruction of the damaged structures. To reduce the risk of intraoperative hemorrhage, shorten the surgery time, and manage potential heartrelated complications, arterial embolization was performed using gelatin sponges and coils. Definitive surgery was then carried out using a skin flap and mucosal flap to successfully reconstruct the defect. Postoperative radiotherapy was deemed unnecessary. The patient recovered well, with a satisfactory aesthetic outcome. No recurrence was observed during a 3-year follow-up period. [ABSTRACT FROM AUTHOR]

Myoepithelial carcinoma (MECA) is a rare type of carcinoma for which the clinicopathological features and prognostic factors have not yet been fully clarified. A retrospective study of 42 patients diagnosed with salivary gland MECA was performed, focusing on the clinicopathological features and prognostic factors. Of the 42 patients, 20 died of cancer, 20 lived without tumour, one lived with distant metastasis, and one was lost to follow-up. Overall, 69.0% had tumour recurrence, 16.7% had cervical nodal metastasis, and 21.4% had distant metastasis. The 5-year overall survival rate was 70.2%. Kaplan–Meier analysis revealed that patients with pathological positive lymph nodes (pN+), multiple recurrences of tumour, and higher histological grade had worse overall survival. Multivariate Cox analysis indicated pN+ and higher histological grade to be independent predictors of decreased survival. The 5-year overall survival rate in the pN0 group was 87.5%, while that in the pN+ group was 28.6%. In conclusion, myoepithelial carcinoma can be defined as a tumour with a high incidence of recurrence and poor prognosis, especially in pN+ patients. Pathological positive lymph nodes and histological grade may serve as predictors of survival. [ABSTRACT FROM AUTHOR]

Myoepitheliomas are uncommon neoplasms of major and minor salivary glands. These tumours are encapsulated and slow growing in nature and are benign in majority of the cases. The mean age of presentation is 40 years and this entity is rarely reported in younger age groups. Here, we seek to report a rare case of a 10-year-old patient who presented with a swelling below the right ear. Clinical and radiological evaluation revealed a mass in the parotid gland. This patient was treated with a superficial parotidectomy and subsequent histopathological examination revealed it to be a myoepithelioma. [ABSTRACT FROM AUTHOR]

Myoepithelioma is a benign salivary gland tumor. Central myoepitheliomas are very rare. The aim of this report was to describe a case of maxillary myoepithelioma. A 14-year-old female patient presented with an multilocular lesion in the anterior maxilla, with nearly 8 months of duration. The lesion was asymptomatic, and the patient's dental history was unremarkable. The diagnostic hypothesis was an odontogenic tumor. Biopsy specimen consisted of nests of plasmacytoid cells in a myxoid stroma without duct formation. No cellular atypia or bone and cartilage formation were noted. The neoplastic cells were positive for Pan-cytokeratin, S100, CK7, and CK8. The final diagnosis was myoepithelioma. The patient was treated by surgical excision followed by bone curettage, and no signs of recurrence were found after 8 years of treatment. [ABSTRACT FROM AUTHOR]

Myoepithelioma is an exceptionally rare tumor, primarily arising in glandular tissues but occasionally found in soft tissues, including the hand. Its occurrence in the hand is particularly uncommon, presenting unique clinical challenges due to the limited number of documented cases and the unusual location. We conducted a literature review in June 2024, with the aim to evaluate the current understanding of hand myoepithelioma, recent diagnostic advances, treatment options, and the diverse presentations of this neoplasm. Articles confirmed that patients present with a painless, slow-growing mass in the hand, often misdiagnosed as more common soft tissue tumors like lipomas or fibromas. Imaging, particularly MRI and ultrasound, aids in assessing the tumor, but definitive diagnosis relies on histopathology, including immunophenotyping. Managing spindle cell myoepithelioma in the hand requires a multidisciplinary approach, with surgical excision being the primary treatment. Achieving clear margins is critical yet challenging due to the hand’s complex anatomy. In some cases, adjuvant therapies such as radiation or chemotherapy may be necessary. The prognosis depends on factors like tumor size, location, and the success of surgical removal, with complete excision typically leading to a favorable outcome.

Ethmoid myoepithelial carcinoma is a rare tumor, with only 14 cases reported to date. This report discusses the largest tumor of this type ever recorded in the ethmoid region. The tumor caused extensive damage to facial structures, complicating treatment. The patient's age and comorbidities increased the risk of intraoperative bleeding, presenting challenges to the complete removal of the tumor and the reconstruction of the damaged structures. To reduce the risk of intraoperative hemorrhage, shorten the surgery time, and manage potential heartrelated complications, arterial embolization was performed using gelatin sponges and coils. Definitive surgery was then carried out using a skin flap and mucosal flap to successfully reconstruct the defect. Postoperative radiotherapy was deemed unnecessary. The patient recovered well, with a satisfactory aesthetic outcome. No recurrence was observed during a 3-year follow-up period.

Tumours of salivary glands are rare and have various histo-pathological subtypes. Myoepitheliomas were first classified by Sheldon et al. and the criterion to classify or diagnose it was first defined by Barnes et al. and Sciubba and Brannon. Myoepithelioma accounts for less than 1 % of all salivary gland tumours, 40 % of these tumours occur in the parotid gland while 21 % occur in the minor salivary glands. A case of myoepithelioma of a minor salivary gland of the cheek is described, emphasizing the problems of the differential diagnosis. A 40-year-old female reported to the department with a complaint of a cheek bite on her right side for a few months. The physical examination showed a presence of lobulated whitish mucosa on the right buccal mucosa at the level of the occlusal plane, on palpation it revealed a non-painful mass approximately 1.5 cm in radius, mobile to bimanual palpation. An excisional biopsy was performed under local anaesthesia. Microscopic and immunohistochemistry confirmed the tumour to be a myoepithelioma of a minor salivary gland with the absence of definitive features of malignancy. Due to their infrequency and multiplicity of histopathology, myoepitheliomas present difficulties in diagnosis. Cellular varieties can be misdiagnosed as malignancies. A key to determining diagnostic criteria for myoepitheliomas is to study cellular morphology, cytoplasmic filament expression, and ultrastructural features of the tumour and apply this information to defining myoepitheliomas. Myoepitheliomas are rare tumours, utilization of immunohistochemical staining and electron microscopy are useful tools for the diagnosis of myoepitheliomas to ensure proper treatment and follow-up. • Myoepithelioma of minor salivary gland • Buccal fat pad reconstruction • Electron microscopy and Immunohistochemistry • Benign salivary gland pathology [ABSTRACT FROM AUTHOR]

Myoepithelial tumors of the soft tissue and bone occurring in patients 21 years of age and younger are rare, and their clinicopathologic features remain incompletely understood. We studied a well-characterized series of 40 such tumors. Cases were retrieved from our archives for the period 2009-2022 and re-reviewed. Available immunohistochemical and molecular genetic data was collected. Clinical information including available follow-up was obtained. The tumors occurred in 18 males and 22 females, ranging from 3 months to 21 years of age (median 11.5 years), and involved a wide variety of soft tissue (n = 36) and bone (n = 4) locations. Histologically benign myoepithelial tumors tended to occur in adolescents (median age 14.5 years; range 5-21 years), whereas myoepithelial carcinomas occurred in younger patients (median age 8.5 years; range 3 months-20 years). Microscopically, the tumors showed a complex admixture of epithelioid, plasmacytoid and spindled cells in a variably hyalinized, myxoid, chondroid or chondromyxoid background. Small subsets of histologically malignant tumors had rhabdoid or "round cell" features. Immunohistochemistry showed 35/40 (88%) cases to be positive with at least one keratin antibody. The 5 keratin-negative tumors were uniformly positive for S100 protein and/or SOX10 and expressed EMA (4 cases) and/or p63 (3 cases). EMA, SMA and GFAP were positive in 21/25 (84%), 13/21 (62%), and 8/21 (38%) tumors, respectively. SMARCB1 and SMARCA4 expression was retained in 29/31 (94%) and 22/22 (100%) of cases, respectively. FISH for EWSR1 gene rearrangement was positive in 6/18 (33%) tested cases. Two EWSR1-negative tumors were also FUS-negative. NGS identified EWSR1::POU5F1, FUS::KLF17, and BRD4::CITED1 gene fusions in 3 tested cases. Clinical follow-up (22 patients; median 23 months; range 1-119 months) showed 3 patients with local recurrences and 5 with distant metastases (lymph nodes, lung, and brain). Three patients died of disease, 3 were alive with recurrent or unresectable disease, and 16 were disease-free. Adverse clinical outcomes were seen only in patients with malignant tumors. We conclude that myoepithelial neoplasms of soft tissue and bone are over-repesented in patients ≤21 years of age, more often histologically malignant, and potentially lethal. Histologic evaluation appears to reliably predict the behavior of these rare tumors., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Concurrent occurrence of schwannoma and meningiomas are rare, and are found especially in association with neurofibromatosis type 2 (NF2). Occurrence of mixed tumor without the aforementioned conditions is extremely rare. We present three cases of mixed tumor in different locations, including two with NF2 and one without NF2. We analyse the relationship of mixed tumor with NF2 and its clinical implications. Presence of mixed schwannoma-meningioma should prompt screening for NF2. Thus aids in early diagnosis of unsuspected NF2 cases. We observed that irrespective of different locations, cases with NF2 showed frequent recurrence of schwannoma as compared to case who did not fit in the existing clinical criteria for NF2. Collision tumor and thereby NF2 mutations indicates the prognosis and recurrence of the tumor, thereby guides in deciding the management., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

SMARCB1/INI1-deficient soft tissue tumors with epithelioid and myxoid features are diverse and mainly include soft tissue myoepithelial tumor, extraskeletal myxoid chondrosarcoma, and the recently described myoepithelioma-like tumor of the vulvar region and myxoepithelioid tumor with chordoid features. Because of their overlapping features, the accurate diagnosis and classification of these tumors are often challenging. Herein, we report two unique cases of SMARCB1/INI1-deficient soft tissue neoplasm with epithelioid and myxoid features occurring in male paratesticular region. The first case was a 52-year-old man presented with an intermittent painful left paratesticular mass for 1 year. The second case was a 41-year-old man presented with a painless paratesticular mass on the right side for 3 months. Both patients underwent an orchiectomy. After 6 and 26 months of follow-up, both were alive with no evidence of recurrence or metastasis. In both cases, the tumor was relatively well-demarcated and showed monomorphic round to epithelioid cells arranged in a nested, trabecular, reticular, and corded pattern, setting in a myxohyalinized and vascularized matrix. The tumor cells showed relatively uniform round nuclei with vesicular chromatin and variably prominent nucleoli. No rhabdoid cells were identified. Mitoses numbered 3 and 2 per 10 high-power fields. Tumor necrosis or lymphovascular invasion was absent. Immunohistochemically, both tumors expressed epithelial membrane antigen (focal), calponin (focal), and CD99. SMARCB1/INI1 expression was deficient in both cases. In addition, case 1 diffusely expressed pan-cytokeratin, and case 2 diffusely expressed CD34 and synaptophysin. Molecular genetically, case 1 showed SMARCB1 homozygous deletion as detected by fluorescence in-situ hybridization (FISH), and case 2 demonstrated SMARCB1 copy number deletions by next-generation sequencing and SMARCB1 monoallelic deletion by FISH. Both cases lacked EWSR1 rearrangements by FISH. The overall clinicopathologic profiles of the two cases made it difficult to classify them as one of the established categories of SMARCB1/INI1-deficient mesenchymal tumors. Our study further expands the clinicopathologic and molecular spectrum of SMARCB1/INI1-deficient epithelioid and myxoid neoplasms and highlights the challenges to diagnose these tumors. • SMARCB1/INI1-deficient soft tissue neoplasms with epithelioid and myxoid features in paratesticular region are exceptional. • Heterogeneity in morphology, immunohistochemistry, and molecular genetics could elicit a wide range of differential diagnoses. • These tumors may have close relationship to myoepithelioma-like tumors of the vulvar region or myxoepithelioid tumors with chordoid features. [ABSTRACT FROM AUTHOR]

Cutaneous mixed tumors exhibit a wide morphologic diversity and are currently classified into apocrine and eccrine types based on their morphologic differentiation. Some cases of apocrine-type cutaneous mixed tumors (ACMT), namely, hyaline cell-rich apocrine cutaneous mixed tumors (HCR-ACMT) show a prominent or exclusive plasmacytoid myoepithelial component. Although recurrent fusions of PLAG1 have been observed in ACMT, the oncogenic driver of eccrine-type cutaneous mixed tumors (ECMT) is still unknown. The aim of the study was to provide a comprehensive morphologic, immunohistochemical, and molecular characterization of these tumors. Forty-one cases were included in this study: 28 cases of ACMT/HCR-ACMT and 13 cases of ECMT. After morphologic and immunohistochemical characterization, all specimens were analyzed by RNA sequencing. By immunohistochemistry, all cases showed expression of SOX10, but only ACMT/HCR-ACMT showed expression of PLAG1 and HMGA2. RNA sequencing confirmed the presence of recurrent fusion of PLAG1 or HMGA2 in all cases of ACMT/HCR-ACMT, with a perfect correlation with PLAG1/HMGA2 immunohistochemical status, and revealed internal tandem duplications of SOX10 (SOX10-ITD) in all cases of ECMT. Although TRPS1::PLAG1 was the most frequent fusion, HMGA2::WIF1 and HMGA2::NFIB were detected in ACMT cases. Clustering analysis based on gene expression profiling of 110 tumors, including numerous histotypes, showed that ECMT formed a distinct group compared with all other tumors. ACMT, HCR-ACMT, and salivary gland pleomorphic adenoma clustered together, whereas myoepithelioma with fusions of EWSR1, FUS, PBX1, PBX3, POU5F1, and KLF17 formed another cluster. Follow-up showed no evidence of disease in 23 cases across all 3 tumor types. In conclusion, our study demonstrated for the first time SOX10-ITD in ECMT and HMGA2 fusions in ACMT and further refined the prevalence of PLAG1 fusions in ACMT. Clustering analyses revealed the transcriptomic distance between these different tumors, especially in the heterogenous group of myoepitheliomas., (Copyright © 2024 United States & Canadian Academy of Pathology. Published by Elsevier Inc. All rights reserved.)