Myoepithelial Tumors: An Update

Fine-needle aspiration cytology of retroperitoneal myoepithelial carcinoma: A rare encounter with diagnostic dilemmas

Myoepithelial carcinoma (MC) arises from the myoepithelial cells. It is a rare tumor with a predilection for salivary glands. MC in soft tissue is uncommon. Soft tissue MC exhibits dual epithelial and smooth muscle phenotype. The extremities and limb girdles are commonly affected. We present cytological findings of retroperitoneal MC with an accurate diagnosis being rendered with the aid of immunocytochemistry on the cell block and demonstration of EWSR1 rearrangements by fluorescence in situ hybridization on cytology smear. The smears were cellular, showing loose clusters and sheets of tumor cells embedded in dense eosinophilic to myxoid matrix material. The cells were oval to polygonal, with focal areas showing moderate nuclear pleomorphism, vesicular to coarse chromatin, and vacuolated cytoplasm with clearing. On immunocytochemistry, tumor cells were positive for epithelial membrane antigen, pan-cytokeratin, calponin, smooth muscle actin, and S-100. A literature review shows only a handful of cases of soft tissue MC. The current report emphasizes the need for cytomorphological awareness with the employment of ancillary testing for accurately diagnosing this rare tumor at an uncommon location. We also discuss the diagnostic challenges and troubleshooting.

Calcifying Spindle Cell Soft Tissue Tumor With SOX10::PLAG1 Fusion: A Case Report of a Morphologically Distinctive and Potentially Novel Soft Tissue Tumor

The widespread use of advanced molecular techniques has led to the identification of several tumor types with PLAG1 gene fusions some of which also affect the skin and soft tissues. Herein, we present a 38-year-old female with a subcutaneous tumor affecting her forearm, which does not seem to fit into any currently recognized entity. It was a well-circumscribed tumor measuring 6 × 4,5 × 4 cm. It had a thick capsule composed of bland spindle cells forming palisades and Verocay body-like structures within a myxocollagenous background. Scattered calcifications were dispersed throughout the lesion. No cytological atypia, mitotic activity, or necrosis were present. Targeted NGS revealed a SOX10::PLAG1 fusion and fluorescent in situ hybridization confirmed the presence of PLAG1 gene rearrangement. The neoplastic cells showed a diffuse immunohistochemical expression of S100, SOX10, and PLAG1, as well as patchy desmin and CD34 positivity. The methylation profile of this tumor did not match any other entity covered by the DKFZ sarcoma classifier and apart from the gain of chromosome 12, the copy number profile was normal. The tumor was completely excised, and the patient has been free of disease for 4 years since the excision. While more cases are needed to confirm this tumor as a distinct entity, we propose a provisional name "SOX10::PLAG1-rearranged calcifying spindle cell tumor."

Myoepithelial Carcinoma of Soft Tissue: Report of Two Cases

CASE

A 40-year-old man was evaluated for a painful mass on his right calf, and a 36-year-old woman presented with a painless mass on her right foot. Final pathology revealed marked nuclear atypia and positivity for S100/SOX10 and AE1/AE3 confirming diagnoses of myoepithelial carcinoma. Both patients underwent surgical resection and are without evidence of local recurrence or metastatic disease at 1-year follow-up.

CONCLUSION

Soft-tissue tumors presenting in the extremities warrant careful evaluation and timely histopathologic diagnosis. Myoepithelial carcinomas are rare, aggressive tumors with a propensity for local recurrence and metastasis. Treatment of these tumors should be discussed by a multidisciplinary tumor team.

Myoepithelial Carcinoma of Sinonasal Cavity: Peculiar Diagnosis, Conventional Treatment

Myoepithelial carcinoma is a morphologically diverse tumor which either arises de novo or from the malignant transformation of its benign counterpart i.e. myoepithelioma. These are relatively lesser known entities and are rarely found in head and neck region. Although rare, their first presentation is usually a painless growing mass as seen in our case presentation as well and are infamous for lymph node recurrence and distant metastasis. Due to their clinical presentation and varied morphology these become tedious to diagnose and pose difficulty for a surgeon when presented at a later date due to their effect on the adjacent vital structures. We report a case of myoepithelial carcinoma in head and neck region arising from the nasal cavity, it's mass effect on the adjacent vital organs and the diagnosis and treatment plan to render the patient free of this tumor, preservation of the vision and keeping the recurrence of the tumor at bay.

Treatment Refractory Soft Tissue Myoepithelial Carcinoma With an ARID1A Mutation

Soft tissue myoepithelial carcinoma is a rare tumor first reported in the salivary gland. There is considerable tumor heterogeneity between pathology findings, tumor aggressiveness, and response to treatment. Recent molecular testing has identified recurrent genetic changes with PLAG mutations in salivary gland primary tumors and loss of SMARCB1 and EWSR1/FUS gene changes in myoepithelial carcinoma. SMARCB1 is a component of the switch/sucrose nonfermentable (SWI/SNF) complex, an essential cellular regulator. ARID1A is another SWI/SNF complex subunit and is a potent oncogenic driver in other tumor types. In this case, we describe the case of an adolescent/young adult patient with treatment refractory soft tissue myoepithelial carcinoma and a previously unreported ARID1A mutation.

Superficial mesenchymal tumours expressing epithelial markers on immunohistochemistry: Diagnostic clues and pitfalls

The diagnosis of mesenchymal neoplasms arising in the superficial soft tissue can be challenging as some entities are rare and show overlapping features. Moreover, the spectrum of mesenchymal tumours has expanded recently to include potential new entities, some of which have been described after the 5th edition of the World Health Organisation (WHO) classification of soft tissue and bone tumours published in 2020. In the skin and superficial soft tissue, tumours of epidermal, melanocytic and appendageal origin are more commonly encountered than mesenchymal neoplasms. However, specific entities from the latter category can occasionally express epithelial markers on immunohistochemistry, some of them in a strong and diffuse manner. It is therefore crucial to be aware of diagnostic pitfalls when encountering cytokeratin positivity in superficial soft tissue neoplasms. This article provides an overview on the differential diagnosis of these mesenchymal tumours that can sporadically occur also in the skin, including myoepithelial neoplasms, epithelioid sarcoma, keratin positive giant cell tumour of soft tissue / xanthogranulomatous epithelial tumour, superficial CD34-positive fibroblastic tumour / PRDM10-rearranged soft tissue tumour, and perineurioma.

Highlighting the Diversity of Desmoplastic Small Round Cell Tumor: A Case Series

Desmoplastic small round cell tumor (DSRCT) is a rare malignant tumor that occurs mainly in the retroperitoneum of children and young adults. In its prototypical form, DSCRT displays characteristic morphology with nested primitive small round cells in a desmoplastic stroma and a distinctive immunophenotype with polyphenotypic differentiation. However, DSCRT can also exhibit a broader clinical, histologic and immunohistochemical spectrum and, therefore, cause diagnostic difficulties. Given that DSCRT is an aggressive and nearly universally fatal disease, making the correct diagnosis is critically important. Herein, we report three patients with DSRCT and unusual clinical, morphologic or immunohistochemical characteristics, in order to highlight its remarkable diversity and increase awareness of this unusual, distinctive neoplasm.

Top Ten Differentials to Mull Over for Head and Neck Myoepithelial Neoplasms

BACKGROUND

Myoepithelial neoplasms of the salivary gland are benign or malignant neoplasms composed exclusively of neoplastic myoepithelial cells. These tumors, including the benign myoepithelioma and the malignant counterpart myoepithelial carcinoma, exhibit a wide range of cytomorphologic features and architectural patterns.

METHODS

Review.

RESULTS

Myoepithelial cells can be epithelial, plasmacytoid, clear cell, spindle cell, and/or oncocytic cell, arranging as trabeculae, solid sheets, nests, cords, and/or single cells. A stromal component is commonly but not universally present, Therefore, their differential diagnoses are quite broad, including salivary gland neoplasms especially those with a myoepithelial component, plasmacytoma, melanoma, and various mesenchymal tumors.

CONCLUSION

In this review, we summarize the characteristic histologic features, useful immunohistochemical panel, and common molecular alterations of myoepithelial tumors and their top differential diagnoses. A logical stepwise algorithmic approach and an immunohistochemical panel to include multiple myoepithelial markers are essential to establish the correct diagnosis.

Myoepithelial carcinoma of the bladder: Case report and review of the literature

Myoepithelial carcinoma is a neoplasm that classically arises in the parotid glands, nasopharynx, paranasal sinus, and nasal cavity of the head and neck. It rarely arises in other organs or soft tissues and involvement of genitourinary organs is distinctly rare. We describe a case of a 21-year-old male, presenting with nausea, weight loss, and worsening suprapubic pain over 3 months, found to have a large mass at the dome of the bladder. Partial cystectomy was ultimately performed revealing myoepithelial carcinoma of the bladder. The patient is free of disease at four years without the need for systemic therapy.

Impending Doom: A Rare Case of Metastatic Myoepithelial Carcinoma

Myoepithelial carcinoma is a rare malignant tumor arising from myoepithelial cells. The usual sites of occurrence are the oral cavity and pharynx with the majority of tumors arising from the salivary gland. However, there have been reported cases of myoepithelial carcinoma seen in the superficial soft tissue, upper respiratory tract, breast, skin, and GI tract. Deep soft tissue myoepithelial carcinoma is relatively uncommon. 

Due to the rarity of this malignancy, consensus on appropriate therapy remains sparse. However, complete resection and/or adjuvant chemotherapy and radiotherapy have been advocated for non-metastatic localized diseases. Sadly, the reported outcome in patients with metastatic disease remains dismal.

In this case, we report a 79-year-old male incidentally found to have a deep soft tissue mass in the sacral area with a coexistent left axillary lymphadenopathy with biopsy and immunohistochemistry confirmation of metastatic myoepithelial carcinoma. He had a rapid clinical deterioration with subsequent fatality.

Myoepithelial carcinoma of major salivary glands: Analysis of population-based clinicopathologic and prognostic features

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The demographic features of major salivary glands myoepithelial carcinoma has been analyzed using propensity score-matching.

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The correlation between tumor stage and prognostic for patients with myoepithelial carcinoma is conformed.

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The radiotherapy is a favorable factor for overall survival in patients with myoepithelial carcinoma.

Background

This study aimed to investigate the effect of demographic characteristics and disease stage on the survival outcomes of patients with myoepithelial carcinoma (MECA) of the salivary glands, and to assess the role of radiotherapy in these patients.

Methods

The Epidemiology, Surveillance and End Results database was queried from 2000 to 2018 to identify patients with MECA. Data pertaining to the tumor stage, size, histological grade, and demographic characteristics were analyzed. The relationship between clinicopathological features and overall survival (OS) was assessed using statistical analyses.

Results

In total, 290 patients (137 men and 153 women) were identified. The parotid gland was the most common tumor location (76.6% patients). Approximately half of the patients had locally advanced tumors, and 14.5 and 6.6% had lymph node and distant organ involvement, respectively. The median OS was 142 months, while the survival rates at 120 months and 180 months were 53% and 39%, respectively. In the cohort, 160 patients (55.2%) underwent surgery alone, while 130 patients (44.8%) underwent surgery combined with radiotherapy. Multivariate Cox analysis revealed that histopathological grade, stage, T3 stage (hazard ratio [HR]: 2.47, P = 0.039), T4 stage (HR: 3.33, P = 0.011), N2 stage (HR: 6.59, P = 0.002), and M1 stage (HR: 2.72, 95%confidence interval [CI]: 1.03–7.19; P = 0.044) were associated with poor prognosis. Radiotherapy (HR: 0.58, P = 0.042) was a favorable factor for OS, and it reduced the mortality risk by 42%.

Conclusions

Histological grade, stage, and radiotherapy are independent risk factors for OS. The decision to administer chemotherapy for MECA should be made with caution. Adjuvant radiotherapy is recommended in high-risk patients.

Cutaneous Myoepithelial Neoplasms on Acral Sites Show Distinctive and Reproducible Histopathologic and Immunohistochemical Features

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.

Myoepithelial tumor in the popliteal area: A diagnostic dilemma

Introduction and importance

Myoepithelial tumors are under-recognized neoplasms that could be difficult to identify due to their rarity and limited comprehension. Their diverse morphology, varied cytologic features and heterogenous immunohistochemical characteristics create a significant diagnostic challenge.

Case presentation

We report the case of a 72-year-old-male patient who received conservative treatment during one year for a popliteal mass on the right knee that showed synovial hyperplasia (benign findings) at initial open tissue biopsy. New symptoms of popliteal area enlargement and discomfort required a second incisional biopsy to reach the diagnosis of a soft tissue myoepithelial tumor through tissue analysis and immunohistochemical staining.

Clinical discussion

The myoepithelial tumors represent a medical dilemma due to their heterogenic features requiring high level of suspicion and adequate immunohistochemical markers for their diagnosis.

Conclusion

Orthopaedic surgeons should be aware of the atypical presentation of these rare neoplasms to provide an early diagnosis and adequate management.

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Consider myoepithelial tumor within the differential of a soft tissue mass.

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Immunohistochemical markers are essential for diagnostic confirmation.

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Surgical resection with negative margins remains the mainstay of treatment.

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There is limited evidence regarding radiotherapy or chemotherapy effectiveness.

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This case highlights the deceiving nature and an unusual location of a myoepithelial tumor.

Cutaneous Melanocytic Tumor with CRTC1::TRIM11 Fusion: Review of the Literature of a Potentially Novel Entity

“Cutaneous melanocytic tumor with CRTC1::TRIM11 fusion” (CMTCT) is a recently described entity belonging to the family of superficial tumors displaying melanocytic differentiation. Thirteen cases have been reported so far, on the head and neck, extremities, and trunk of adults of all ages (12 cases) and one in an 11-year-old child. Histopathologically, it is a nodular or multilobulated tumor composed of spindle and epithelioid cells arranged in nests, fascicles, or bundles that are surrounded by thin collagenous septa. By immunohistochemistry, the tumor shows variable immunoreactivity for S100-protein, SOX10, and MITF, as well as specific melanocytic markers such as MelanA and HMB-45. The neoplasm’s biologic behavior remains uncertain since the reported cases are limited and the follow-up is short (median 12 months). However, local recurrence and synchronous distant metastasis after 13 years of initial resection has been described in one case. Herein, we present a comprehensive literature review of CMTCT hoping to raise awareness among the dermatopathologists of this potentially novel entity.

Myoepithelial Carcinoma of Soft Tissue With an EWSR1-KLF15 Gene Fusion in an Infant

Overall, neonatal cancer is uncommon. Because of its rarity and heterogeneity, diagnosis can be challenging. We report a unique case of a myoepithelial carcinoma in a 7 week old girl. Molecular diagnostic workup revealed a EWSR1-KLF15 gene fusion which was previously described in only six cases of myoepithelial tumors so far. All cases occurred in children and adolescents. To our knowledge, this is the first report of a congenital EWSR1-KLF15 fusion positive myoepithelial tumor in an infant.

Primary high-grade myoepithelial carcinoma of the lung: A study of three cases illustrating frequent SMARCB1-deficiency and review of the literature

Primary myoepithelial carcinoma of the lung is exceptionally rare and, hence, remained poorly characterized. We present 3 tumors affecting 2 males and 1 female aged 60 to 84 years. Tumor size ranged from 4 to 10 cm. All presented as well circumscribed non-encapsulated peripheral solitary masses. One patient died postoperatively. The other two were lost to follow-up. Histologically, all tumors were high-grade with predominance of myxoid/chordoid (2) and rhabdoid (1) pattern. Immunohistochemistry (IHC) showed reactivity with vimentin, pankeratin, EMA and smooth muscle actin. Two tumors were SMARCB1-deficient (one with additional loss of SMARCA2 and PBRM1). RNA sequencing revealed no gene fusions. Review of reported cases (total: 16) showed that pulmonary myoepithelial carcinoma affects both sexes equally at a median age of 60 years (24-84), presents predominantly as peripheral masses (69%) in the lower lobes (66%) of smokers (70%) with a median size of 6 cm (1.5-13), and originates as high-grade de novo carcinoma. Forty percent of patients died of disease at a median of 12.5 months (0 to 62). Only 40% of patients were disease free at last follow-up (median, 9.5 months). Prominent lobulation and myxoid stroma were frequent histological features. Most tumors displayed variable combinations of epithelioid, spindle, plasmacytoid, clear, ovoid or round cells. Three of 6 tumors subjected to different RNA panels showed EWSR1 rearrangements (fused to PBX1, ZNF444 or to unknown partner). Two of 3 tumors lacking gene fusions were SMARCB1-deficient (both showed secondary EWSR1 FISH abnormalities due to 22q deletion). Primary pulmonary myoepithelial carcinoma is a rare aggressive malignancy that recapitulates its soft tissue and salivary counterpart. Exclusion of metastasis from other primaries is mandatory and can only be achieved by detailed clinical history and imaging.

Dermal melanocytic tumor with CRTC1-TRIM11 fusion: Report of two additional cases with review of the literature of an emerging entity

"Cutaneous melanocytic tumor with CRTC1-TRIM11 fusion" (CMTCT) is a newly described, potentially novel entity that typically presents as a dermal nodule on the head and neck, extremities, and trunk of adults. Histopathologically, it is reported as a nodular or multinodular tumor composed of epithelioid and spindle cells that are variably immunoreactive for S100-protein, SOX10, and MITF along with more specific melanocytic markers such as MelanA and HMB45. With only 11 cases reported in the English literature so far, the neoplasm appears to behave in a relatively indolent fashion. Nevertheless, in one case, local recurrence and synchronous distant metastasis were evident after 13 years. Additional cases with longer follow-up are essential to determine the neoplasm's biologic behavior with more accuracy. Herein, two cases of CMTCT, one arising on the lower back of a 65-year-old female and the other on the arm of a 33-year-old female in addition to a comprehensive literature review are reported.

Primary parasagittal myoepithelioma in a paediatric patient: review of the literature and illustrative case

Myoepithelial tumours are a rare form of salivary gland neoplasm, and their occurrence in the central nervous system is exceedingly rare. The authors report the case of an 18-year-old Filipino man presenting with headache and weakness, and on imaging showing an extensive parasagittal tumour at the left posterior parietal area with extracalvarial extension. There was no systemic disease. The patient underwent surgery to excise the tumour, with histopathology showing findings consistent with myoepithelioma. There was no further treatment, given the benign histology of the lesion, but there was recurrence after 8 months. Repeat surgery was done for the patient and he is for adjuvant radiotherapy. This appears to be the 10th reported case of a central nervous myoepithelioma, and the first case in the Philippines of a primary parasagittal myoepithelioma in a paediatric patient. Further information is needed to provide diagnostic and therapeutic recommendations.

Soft tissue myoepithelial carcinoma-a case report with molecular and electron microscopic analysis

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.

NDRG1-PLAG1 and TRPS1-PLAG1 Fusion Genes in Chondroid Syringoma

BACKGROUND/AIM

Chondroid syringoma is a rare benign tumor emanating from sweat glands. Although rearrangements of the pleomorphic adenoma gene 1 (PLAG1) have been reported in such tumors, information on PLAG1 fusion genes is very limited.

MATERIALS AND METHODS

Cytogenetic, fluorescence in situ hybridization, RNA sequencing, array comparative genomic hybridization, reverse transcription polymerase chain reaction, and Sanger sequencing analyses were performed on two chondroid syringoma cases.

RESULTS

Both tumors had structural rearrangements of chromosome 8. An NDRG1-PLAG1 transcript was found in the first tumor in which exon 3 of PLAG1 was fused with exon 1 of NDRG1. A TRPS1-PLAG1 chimeric transcript was detected in the second chondroid syringoma in which exon 2 or exon 3 of PLAG1 was fused with exon 1 of TRPS1.

CONCLUSION

The NDRG1-PLAG1 and TRPS1-PLAG1 resemble other PLAG1 fusion genes inasmuch as the expression of PLAG1 comes under the control of the NDRG1 or TRPS1 promoter.

Cutaneous Myoepithelioma: An Unusual Tumor in the Hand

Cutaneous myoepithelioma (CM) is a rare tumor among the primary skin neoplasms. We present the case of a patient with a diagnosis of CM in the right hypothenar region. Histological study showed a proliferation of myoepithelial cells with a solid, reticular growth pattern in a chondromyxoid stroma. The tumor cells were positive for CK AE, S-100, EMA, and p63.

Ossifying Fibromyxoid Tumor: A Review With Emphasis on Recent Molecular Advances and Differential Diagnosis

CONTEXT.—

Ossifying fibromyxoid tumor (OFMT) is a rare, slow-growing mesenchymal neoplasm of uncertain histogenesis with intermediate malignant potential.

OBJECTIVE.—

To highlight the most important diagnostic features, including morphologic, immunohistochemical, and molecular findings; to provide comparisons to other entities in the differential diagnosis; and to provide a summary of the clinical features and outcomes in cases reported to date.

DATA SOURCES.—

The data sources include recently published literature encompassing OFMT and tumors in the histologic differential diagnosis, and cases from institutional files.

CONCLUSIONS.—

Ossifying fibromyxoid tumor is important to recognize because of its low-grade morphology but potential for recurrence and metastasis. Recent molecular analysis has expanded the morphologic spectrum of OFMT, with additional cases discovered that are enriched for aggressive behavior. The diagnosis can often be rendered through a combination of morphology and coexpression of S100 protein and desmin, although only a minority of cases described contain all of these primary features. In cases that do not have all of these features, a high index of suspicion guided by morphology and exclusion of other tumors in the histologic differential diagnosis can lead to the correct diagnosis. Growing access to molecular genetic testing will become increasingly important for correct diagnosis of tumors at the ends of the morphologic spectrum.

Metachronous Pancreatic and Thyroid Metastases from Primary Soft-Tissue Myoepithelioma in the Clavicular Region: A Case Report of a Long-Term Survivor

Patient: Male, 69-year-old

Final Diagnosis: Metachronous pancreatic and thyroid metastases from primary soft tissue myoepithelioma

Symptoms: None

Medication:—

Clinical Procedure: Surgery

Specialty: Surgery

Fusion of the Genes PHF1 and TFE3 in Malignant Chondroid Syringoma

BACKGROUND/AIM

Malignant chondroid syringoma is a rare tumor of unknown pathogenesis.

MATERIALS AND METHODS

Genetic analyses were performed on a malignant chondroid syringoma.

RESULTS

G-banding analysis of short-term cultured tumor cells yielded the karyotype 46,Y,t(X;6)(p11;p21)[15]/46,XY[2]. RNA sequencing detected an in-frame fusion of PHF1 from 6p21 with TFE3 from Xp11, verified by RT-PCR and Sanger sequencing. Genomic PCR showed that the PHF1-TFE3 junction was identical to the fusion found by RNA sequencing and RT-PCR.

CONCLUSION

Malignant chondroid syringoma is genetically related to tumors with PHF1 rearrangements such as low-grade endometrial sarcoma and ossifying fibromyxoid tumor, but also with tumors having TFE3 rearrangements such as renal cell carcinoma, alveolar soft part sarcoma, PEComa, and epithelioid hemangioendothelioma. Further investigations on malignant chondroid syringomas are needed in order to determine whether genetic heterogeneity exists among them and the clinical impact of the PHF1-TFE3 fusion.

Cutaneous soft tissue tumors: diagnostically disorienting epithelioid tumors that are not epithelial, and other perplexing mesenchymal lesions

Cutaneous soft tissue tumors with epithelioid features present a diagnostic challenge given that many entities in this category are rare, and they show morphologic overlap with significantly more common cutaneous epithelial and melanocytic neoplasms. The challenge is compounded by overlapping expression of epithelial or melanocytic markers in some of these entities. A broad spectrum of primary cutaneous epithelioid soft tissue tumors exists, including benign and malignant counterparts of tumors with various differentiation including melanocytic, peripheral nerve sheath, angiomatous, fibrohistiocytic, and myoid or myoepithelial, in addition to translocation-associated tumors lacking a derivative tissue type. Given this spectrum, an initial targeted immunohistochemical panel for epithelioid dermal and subcutaneous neoplasms is recommended, covering a broad spectrum of differentiation. In diagnostically challenging cases, select molecular studies can be employed to make critical distinctions between entities sharing morphologic and immunohistochemical properties. Due to sometimes marked differences in prognosis and treatment, knowledge and familiarity with epithelioid soft tissue tumors is key for any surgical pathologist who evaluates skin and subcutaneous biopsies and excision specimens. This concise review provides brief descriptions, key diagnostic features, and important modern ancillary studies for the diagnosis of non-epithelial, non-melanocytic cutaneous tumors that can exhibit a prominent degree of epithelioid morphology.

Metastasis of malignant myoepithelial carcinoma to the brain

Myoepithelial tumours are a rare form of salivary gland neoplasm and intracranial metastases have rarely been described. The authors present the case of a 61-year-old patient with a history of primary myoepithelial carcinoma of the right foot. Metastases were found in the third ventricle, left temporal lobe and right frontal lobe. The third ventricular and left temporal lobe tumours were resected in a two-stage operation. Pathology of the third ventricular lesion was most consistent with metastasis. MRI of the spine 2 weeks after his operation revealed an intradural mass with several lesions in the lumbar thecal space suggesting further metastases. The patient succumbed to his disease 2 months after his two-stage operation and 5 years after his initial diagnosis. This appears to be the first case in the literature of multiple primary myoepithelial carcinoma metastases to the brain. Further information is needed to provide diagnostic and therapeutic recommendations.

Nonepithelial Tumors and Tumor-like Lesions of the Skin and Subcutis in Children

This overview of mesenchymal tumors presenting in the skin and/or subcutis in children brings together the range of neoplasms and hamartomas which are seen in this age-group. It is not surprising from the perspective of the pediatric or general surgical pathologist that vascular anomalies, including true neoplasms and vascular malformations, are the common phenotypic category. Since there is considerable morphologic overlap among these lesions, clinicopathologic correlation may be more important than for many of the other mesenchymal tumors. The skin and subcutis are the most common sites of clinical presentation for the infantile myofibroma which is the most common of fibrous mesenchymal tumors in children. Several of the other mesenchymal tumors are more common adults-like dermatofibrosarcoma protuberans, but nonetheless have an important presence in children, even as a congenital neoplasm. A lipomatous tumor in a young child should be considered as a possible manifestation of an overgrowth syndrome.

Myoepithelioma of soft tissue: A cytological-pathological correlation with literature review

Myoepitheliomas of soft tissue are rare tumors with variable morphologic, immunohistochemical and molecular profiles and therefore are diagnostically challenging for pathologists. We report a case in a 60-year-old male with a painless slowly growing 3cm mass on left medial forefoot. Core biopsy of the mass showed a neoplastic proliferation of plasmacytoid tumor cells, consistent with myoepithelioma of soft tissue. Immunohistochemical stains demonstrated positivity of the tumor cells for cytokeratin AE1/AE3, CK18, S-100 protein and myosin heavy chain (SMMS-1), supporting the diagnosis. Fine-needle aspiration was performed intraoperatively before the resection of the mass. Air-dried Diff-Quik stained cytology slides showed singly scattered and loosely cohesive clusters of plasmacytoid and spindle cells with dense basophilic cytoplasm, distinct cytoplasmic borders, and round to oval mildly pleomorphic nuclei with smooth nuclear membrane. Scattered naked nuclei, binucleated tumor cells, as well as tumor cells with wispy elongated cytoplasm were also seen. Occasional clusters of cells were intimately associated with metachromatic fibrillary stromal material. Histologic examination of the resected tumor confirmed the diagnosis of myoepithelioma. Molecular studies showed absence of EWSR1 rearrangement. Cytological differential diagnosis, clinical, histological, immunohistochemical, and molecular features of soft tissue myoepitheliomas are discussed in this study.

Pleural fluid metastases of myoepithelial carcinoma: A case report and review of the literature

Myoepithelial carcinoma (MECA) is one of the rarest salivary gland neoplasms, which may either arise de novo or develop within a preexisting pleomorphic adenoma or benign myoepithelioma. The tumor occurs mainly in the parotid gland followed by minor salivary glands and other body sites. As a result of their morphologic heterogeneity, they can be confused easily with many tumors. Awareness of their unique cytoarchitectural patterns and immunohistochemical profile is crucial for accurate identification. Herein, we report a rare case of a 51-year-old female patient with MECA of the maxillary sinus that metastasized to the pleural fluid. To the best of our knowledge, this is the first case of pleural fluid involvement by MECA reported in the literature.