Clear Cell Sarcoma–like Tumor of the Gastrointestinal Tract: An Evolving Entity

Mesenchymal Tumors of the Tubular Gastrointestinal Tract (Non-GIST): The GI Pathologist's Approach

Mesenchymal neoplasms of the gastrointestinal tract are rare compared with epithelial lesions. However, over the past few decades, the increasing volume of gastrointestinal endoscopy has expedited the recognition of several novel entities with varying clinical significance. Its spectrum extends from reactive changes and benign neoplasms to highly aggressive sarcomas. At the malignant end of the spectrum, the importance of correctly diagnosing these tumors is underscored by the specific therapeutic implications available for some tumor types (eg, tyrosine kinase inhibitors for gastrointestinal stromal tumors) that allow personalized treatments. Benign lesions frequently surface among routine polypectomy specimens, sometimes offering diagnostic challenges. However, precise classification is the only way to avoid prognostic uncertainty and overtreatment, and to recognize possible syndromic associations. Hereby, we offer a pragmatic review of the topic from the gastrointestinal pathologist's perspective, who, although more accustomed to epithelial neoplasms, can use an algorithmic approach to diagnose mesenchymal entities successfully.

EWSR1::CREM rearranged intra-abdominal malignant epithelioid neoplasm: two new cases of an emerging entity with clinicopathological characteristics and histological pitfalls

The EWSR1::CREM rearranged intra-abdominal malignant epithelioid neoplasm is an emerging tumor, with only a few publications describing it to date. Here, we report two new cases of this highly aggressive tumor, primarily involving the peritoneal surface. The tumors presented as a widespread diffuse peritoneal lesion associated with a 4-cm pelvic mass in a 28-year-old woman (Case 1) and as a 10-cm intra-abdominal mass infiltrating the stomach with multiple hepatic metastases in a 53-year-old woman (Case 2). The tumors shared predominant epithelioid morphology with minimal nuclear polymorphism. One of them additionally harbored spindle and rhabdoid cell populations. Both tumors displayed immunoreactivity for pan-cytokeratins, EMA, and CD99, and variable positivity for MUC4, progesterone and estrogen receptors, pan-NTRK, and synaptophysin. This misleading histology and immunophenotype give rise to a wide spectrum of differential diagnoses and highlight the crucial role of RNA sequencing in diagnostic accuracy and thus in appropriate therapeutic approaches.

EWSR1: the promiscuous king of mesenchymal neoplasia

EWSR1 is the most commonly rearranged gene in mesenchymal neoplasia, and its myriad chimeric oncoproteins drive widely disparate neoplasms. Here, we survey selected EWSR1 rearrangements, including well-described EWSR1 fusions with CREB family members, ATF1 and CREB1, as well as fusions in emerging entities such as mesenchymal neoplasms with EWSR1::PATZ1 and EWSR1::NFATC2 fusions. We also discuss recent data demonstrating the imperfect specificity of EWSR1::WT1 and, possibly, EWSR1::FLI1 fusions.

Malignant Gastrointestinal Neuroectodermal Tumor, a Rare Neoplasm, Presenting With Hemoperitoneum and Malena: A Case Report

Malignant gastrointestinal neuroectodermal tumor (GNET) are rare malignant mesenchymal tumors. The tumor can present with various symptoms like abdominal pain, anorexia, or small bowel obstruction. Here, we present a case of small intestinal GNET who presented with gastrointestinal bleed and hemoperitoneum, a rare presentation of this disease. This patient was misdiagnosed initially as Crohn's disease and treated for the same. However, non-response to the standard treatment and onset of new symptoms like malena and ascites raised the suspicion of some alternate diagnosis. Exploratory laparotomy showed the presence of hemoperitoneum along with a mass, 100 cm proximal to ileo-cecal junction. She was successfully treated with surgical resection and anastomosis. Histopathology, immunohistochemistry (diffuse positivity for S100 and weak positivity for synaptophysin) and molecular fluorescence in-situ hybridization (FISH) study (translocation involving the chromosomal region 2212.1-q12.2 which harbors EWSR1 gene) confirmed the diagnosis of GNET.

Essential role of postoperative follow-up in the management of clear cell sarcoma

Clear cell sarcoma (CCS) is a rare melanocytic soft tissue sarcoma known for its propensity to metastasize to the lymph nodes and typically has an unfavorable prognosis. Currently, surgical resection is the primary treatment for localized CCS, while radiotherapy and chemotherapy are preferred for metastatic cases. The roles of adjuvant chemotherapy, radiotherapy, and lymph node dissection are controversial. Although immunotherapy has emerged as a promising avenue in CCS treatment research, there are no established clinical standards for postoperative follow-up. This editorial discusses a recent article by Liu et al, with a focus on current diagnostic modalities, treatment approaches, and the challenging prognosis associated with CCS. Our aim is to underscore the importance of long-term patient follow-up in CCS management.

Intra-Abdominal Epithelioid Neoplasm With EWSR1::CREB Fusions Involving the Kidney: A Clinicopathologic and Molecular Characterization With an Emphasis on Differential Diagnosis

Soft tissue neoplasms, harboring fusions between EWSR1 and FUS with genes encoding CREB transcription factors family (ATF1, CREB1, and CREM), are an emerging heterogeneous group of mesenchymal tumors that differ significantly in morphology, immunophenotypes, and behavior. Recently, EWSR1/FUS::CREB fusions have been recognized to define a group of aggressive neoplasms of epithelioid morphology with multiple growth patterns and a striking predilection for mesothelial-lined cavities. These neoplasms presenting as a primary neoplasm of intra-abdominal visceral organs are rare, which could elicit a wide range of differential diagnoses because of their diverse morphologies and immunohistochemical profiles. We report 3 cases of intra-abdominal epithelioid neoplasms with EWSR1::CREB fusions involving the kidney. This study included 2 female patients and 1 male patient, with age at presentation ranging from 17 to 61 years (mean: 32 years). All the patients underwent radical nephrectomy without adjunctive therapies. Grossly, the tumors were large, and all were solitary masses with sizes ranging from 5.6 to 30.0 cm (mean: 14.5 cm). Histologically, the neoplasms showed infiltrating and indistinct borders and were composed predominantly of monomorphic round-to-epithelioid cells with variable amounts of pale-to-clear cytoplasm, arranged in cords, nests, and sheets and embedded in a sclerotic hyalinized stroma with variable lymphoid cuffing either intermixed or at the periphery. Notably, a hemangiopericytomatous growth pattern was commonly seen. Nuclear atypia was mild, and mitotic activity was scarce. Immunohistochemically, all 3 cases were at least focally positive for epithelial membrane antigen and keratin AE1/AE3, with 2 tumors showing focal MUC4 expression and 1 case displaying diffuse CD34 and focal CAIX positivity. Targeted RNA sequencing identified EWSR1::CREM fusion in 2 cases and EWSR1::ATF1 fusion in 1 case. Subsequent fluorescence in situ hybridization analysis confirmed the RNA sequencing results. On follow-up, 1 patient developed multiple spinal bone metastases 5 months after the surgery while the other 2 patients were free of disease 9 and 120 months after diagnosis, respectively. Our findings demonstrate that intra-abdominal epithelioid neoplasms with EWSR1::CREB fusions may rarely occur primarily in the kidney and should be included in the differential diagnosis of primary renal epithelioid mesenchymal neoplasms.

Malignant Gastrointestinal Neuroectodermal Tumor (GNET) Mimicking Small Bowel Lymphoma: A Case Report

A malignant gastrointestinal neuroectodermal tumor (GNET) is a rare entity, characterized as a malignant mesenchymal neoplasm occurring exclusively near the gastrointestinal tract, prone to frequent local recurrence and metastasis. Here, we report a case of a 49-year-old male presented with abdominal pain and weight loss. The patient had a remote history of thymic B-cell lymphoma. An abdominal computed tomography (CT) scan revealed a focal wall thickening of the terminal ileum with mesenteric lymphadenopathy, suggestive of lymphoma. A core needle biopsy of the mesenteric node was inconclusive. A right hemicolectomy was subsequently performed. Histologically, abundant multinucleated osteoclast-like giant cells are present. The tumor cells show diffuse strong positivity for S100 and SOX10. EWSR1-ATF1 gene fusion was identified by fluorescence in situ hybridization (FISH), consistent with a diagnosis of GNET. This case emphasizes a diagnostic challenge of a rare malignancy.

Small Intestine Gastrointestinal Clear Cell Sarcoma: A Case Report and Review of the Literature

Gastrointestinal clear cell sarcoma (GICCS)/malignant gastrointestinal neuroectodermal tumor (GNET) is an extremely rare form of cancer with aggressive clinical behavior. It has distinct pathological, immunohistochemical, ultrastructural, and molecular features. Herein, we present the case of a 20-year-old woman with no notable medical history who presented to the outpatient department with complaints of abdominal pain and vomiting. Symptoms had been evolving for 3 months. The physical examination revealed slight abdominal tenderness and melena. Biological investigations revealed iron-deficiency anemia. The upper and lower endoscopies showed no abnormalities. Magnetic resonance enterography revealed small bowel wall thickening of 15 mm × 2 mm. Exploratory laparotomy revealed an ileal mass with mesenteric lymphadenopathy. A wide resection of the mass was then performed. The final pathological report confirmed the diagnosis of small bowel GICCS/GNET. After 11 months of follow-up, the patient presented with mesenteric lymph node metastases.

Gastrointestinal Neuroectodermal Tumor/Extraskeletal Ewing Sarcoma of the Ileum with Ulcerative Colitis

Introduction

Malignant gastrointestinal neuroectodermal tumor (GNET), previously known as clear cell sarcoma-like tumor of the gastrointestinal tract, is an extremely rare and aggressive mesenchymal neoplasm characterized by high rates of recurrence, metastases, and mortality. Currently, there are no standardized guidelines for therapy.

Case Presentation

We present a case of GNET in a 32-year-old male with a history of lymphoma and ulcerative colitis (UC), who also had synchronous multiple liver metastasis. To our knowledge, this is the first documented case of GNET in a patient with inflammatory bowel disease.

Conclusion

The narrow time frame in which UC and GNET were diagnosed warrants further investigation into their potential relationship.

Clear Cell Sarcoma-Like Tumor of the Gastrointestinal Tract with Peritoneal Metastasis in a Young Adult: A Case Report with Literature Review

Clear cell sarcoma-like tumor of the gastrointestinal tract (CCSLTGT) is a rare malignant mesenchymal tumor of the gastrointestinal (GI) tract with a high probability of local recurrence and distant metastasis in young adults. To the best of our knowledge, only seven case reports have described the imaging findings of a CCSLTGT originating from in the small intestine in English literatures so far. Therefore, we report the imaging findings of a CCSLTGT that occurred in the small intestine of a 22-year-old female and summarize the imaging findings of the previous reports.

Functional genomics of human clear cell sarcoma: genomic, transcriptomic and chemical biology landscape for clear cell sarcoma

BACKGROUND

Systemic therapy for metastatic clear cell sarcoma (CCS) bearing EWSR1-CREB1/ATF1 fusions remains an unmet clinical need in children, adolescents, and young adults.

METHODS

To identify key signaling pathway vulnerabilities in CCS, a multi-pronged approach was taken: (i) genomic and transcriptomic landscape analysis, (ii) integrated chemical biology interrogations, (iii) development of CREB1/ATF1 inhibitors, and (iv) antibody-drug conjugate testing (ADC). The first approach encompassed DNA exome and RNA deep sequencing of the largest human CCS cohort yet reported consisting of 47 patient tumor samples and 8 cell lines.

RESULTS

Sequencing revealed recurrent mutations in cell cycle checkpoint, DNA double-strand break repair or DNA mismatch repair genes, with a correspondingly low to intermediate tumor mutational burden. DNA multi-copy gains with corresponding high RNA expression were observed in CCS tumor subsets. CCS cell lines responded to the HER3 ADC patritumab deruxtecan in a dose-dependent manner in vitro, with impaired long term cell viability.

CONCLUSION

These studies of the genomic, transcriptomic and chemical biology landscape represent a resource 'atlas' for the field of CCS investigation and drug development. CHK inhibitors are identified as having potential relevance, CREB1 inhibitors non-dependence of CCS on CREB1 activity was established, and the potential utility of HER3 ADC being used in CCS is found.

"E-MGNET": Extra-Enteric Malignant Gastrointestinal Neuroectodermal Tumor- A Clinicopathological and Molecular Genetic Study of 11 Cases

Malignant gastrointestinal neuroectodermal tumors (MGNET), also known as "gastrointestinal clear cell sarcoma-like tumor", are very rare, aggressive sarcomas characterized by enteric location, distinctive pathologic features, and EWSR1/FUS::ATF1/CREB1 fusions. Despite identical genetics, the clinicopathologic features of MGNET are otherwise quite different from clear cell sarcoma of soft parts (CCS). Only exceptional extra-enteric MGNET (E-MGNET) have been reported. We report a series of 11 E-MGNET, the largest to date. Cases diagnosed as MGNET and occurring in non-intestinal locations were retrieved. Clinical follow-up was obtained. The tumors occurred in 3 males and 8 females (14-70 years of age, median 33 years) and involved the soft tissues of the neck (3), shoulder (1), buttock (2), orbit (1), and tongue/parapharyngeal space (1), the urinary bladder (1) and the falciform ligament/liver (1). Tumors showed morphologic features of enteric MGNET (small, relatively uniform, round to ovoid cells with round, regular nuclei containing small nucleoli, growing in multinodular and vaguely lobular patterns, with solid, pseudoalveolar and pseudopapillary architecture). Immunohistochemical results were: S100 protein (11/11), SOX10 (11/11), synaptophysin (3/10), CD56 (7/9), CD117 (3/9), DOG1 (0/4), ALK (4/8), chromogranin A (0/10), HMB45 (0/11), Melan-A (0/11), tyrosinase (0/4), MiTF (0/11). NGS results were: EWSR1::ATF1 (7 cases), EWSR1::CREB1 (3 cases) and EWSR1::PBX1 (1 case). The EWSR1::PBX1-positive tumor was similar to other cases, including osteoclast-like giant cells, and negative for myoepithelial markers. Clinical follow-up (range: 10 to 70 months; median 34 months) showed 4 patients dead of disease (10.5, 12, 25 and 64 months after diagnosis), 1 patient alive with extensive metastases (43 months after diagnosis), 1 patient alive with persistent local disease (11 months after diagnosis), and 4 alive without disease (10, 47, 53 and 70 months after diagnosis). One case is too recent for follow-up. The clinicopathologic and molecular genetic features of rare E-MGNET are essentially identical to those occurring in intestinal locations. Otherwise-typical E-MGNET may harbor EWSR1::PBX1, a finding previously unreported in this tumor type. As in enteric locations, the behavior of E-MGNET is aggressive, with metastases and/or death from disease in at least 50% of patients. E-MGNET should be distinguished from CCS and other tumors with similar fusions. ALK expression appears to be a common feature of tumors harboring EWSR1/FUS::ATF1/CREB1 fusion but is unlikely to predict therapeutic response to ALK inhibition. Future advances in our understanding of these unusual tumors will hopefully lead to improved nomenclature.

The Malignant Gastrointestinal Neuroectodermal Tumor (GNET): A Distinct Entity and the Challenging Differential Diagnosis with Mesenchymal, Lymphoid, and Melanic Tumors: A Case Report and Brief Review of the Literature

(1) Background: A malignant gastrointestinal neuroectodermal tumor (GNET) is an ultra-rare primary neoplasm with a distinctive histopathological, immunohistochemical, molecular, and ultramicroscopic profile, synonymous terminology with clear cell sarcoma-like tumor of the gastrointestinal tract. This case report aims to describe a case of GNET with challenging mesenchymal, lymphoid, and melanic tumor differential diagnosis. (2) Case presentation: We discuss the case of a 67-year-old male patient who presented with diffuse abdominal pain, intermittent lack of intestinal transit, and frequent episodes of nausea, followed by segmental resection of the jejunum and sigmoid colon. The patient had no relevant medical history. The surgical specimen underwent immunohistochemical staining and morphological evaluation. (3) Results: Histopathological analysis reveals a moderately homogeneous polyhedral-epithelioid and spindle cell neoplastic proliferation with a zonal discohesive pattern and extensive and focal fasciculated architecture. Twenty monoclonal antibodies were used for immunostaining, which allowed GNET to be diagnosed on the basis of the tumoral immune profile, characterized by positive reactivity of S100, SOX10, and CD 56. (4) Conclusions: The poor prognosis of GNET is highlighted in the present study, along with the vital importance of differential diagnosis issues with mesenchymal, lymphoid, and melanic tumors, which make the diagnosis difficult for both pathologists and clinicians.

New progress with calcium-binding protein S100A16 in digestive system disease

INTRODUCTION

This review summarizes and analyzes the abnormal expression and mechanism of S100A16 in digestive system diseases, which is expected to provide new ideas and methods for adjuvant treatment and prognosis evaluation of digestive system diseases.

AREAS COVERED

Based on original publications found in database systems (PubMed, Cochrane), we introduce the mechanism and research progress of S100A16 in digestive system tumors, inflammatory bowel disease and fatty liver.

EXPERT OPINION

S100A16 is closely related to the proliferation, migration, and invasion of digestive system tumor cells. Further, it plays an important role in inflammatory bowel disease and fatty liver.

Exploration of Flavonoids as Lead Compounds against Ewing Sarcoma through Molecular Docking, Pharmacogenomics Analysis, and Molecular Dynamics Simulations

Ewing sarcoma (ES) is a highly malignant carcinoma prevalent in children and most frequent in the second decade of life. It mostly occurs due to t(11;22) (q24;q12) translocation. This translocation encodes the oncogenic fusion protein EWS/FLI (Friend leukemia integration 1 transcription factor), which acts as an aberrant transcription factor to deregulate target genes essential for cancer. Traditionally, flavonoids from plants have been investigated against viral and cancerous diseases and have shown some promising results to combat these disorders. In the current study, representative flavonoid compounds from various subclasses are selected and used to disrupt the RNA-binding motif of EWS, which is required for EWS/FLI fusion. By blocking the RNA-binding motif of EWS, it might be possible to combat ES. Therefore, molecular docking experiments validated the binding interaction patterns and structural behaviors of screened flavonoid compounds within the active region of the Ewing sarcoma protein (EWS). Furthermore, pharmacogenomics analysis was used to investigate potential drug interactions with Ewing sarcoma-associated genes. Finally, molecular dynamics simulations were used to investigate the stability of the best selected docked complexes. Taken together, daidzein, kaempferol, and genistein exhibited a result comparable to ifosfamide in the proposed in silico study and can be further analyzed as possible candidate compounds in biological in vitro studies against ES.

Case report and literature review: Small bowel intussusception due to solitary metachronous metastasis from renal cell carcinoma

Introduction

Solitary metachronous small bowel metastasis from renal cell carcinoma (RCC) is rare. In contrast to idiopathic intussusception frequently occurring in children, adult intussusception is fairly uncommon and usually indicates a malignancy.

Case presentation

We presented an 84-year-old man with small bowel intussusception and obstruction due to a solitary metachronous metastasis from RCC. Computed tomography with intravenous contrast revealed small bowel obstruction and a 4 × 4 cm intraluminal soft-tissue mass with moderate enhancement. During urgent exploratory laparotomy, a pedunculated tumor of the distal ileum was found to be the lead point of intussusception. Hence, reduction of the intestinal invagination and segmental resection of the ileum with functional end-to-end anastomosis were performed. Histological examination finally confirmed the diagnosis. The postoperative recovery was uneventful. The patient was discharged without any complications on postoperative day 6.

Conclusion

The case report highlights the rarity of solitary metachronous small bowel metastases from RCC and suggests that life-long follow-up of RCC patients is critical due to its unpredictable behavior and the possibility of a long period of dormancy. Complete surgical resection remains the mainstay treatment for such patients.

[Malignant gastrointestinal neuroectodermal tumor: A report of 2 cases and a review of the literature]

Malignant gastrointestinal neuroectodermal tumour (GNET) is an extremely rare neoplasm first described by Zambrano in 2003 as clear cell sarcoma like tumor of the gastrointestinal tract. In contrast to clear cell sarcoma, it has giant osteoclast cells and shows diffuse and intense positivity for S-100 with no immunohistochemical or ultrastructural melanocyte differentiation. We present the first cases of GNET reported in South America, occurring in Peru. Two cases of GNET, one in a female and one in a male, both between 60 and 70 years of age, were referred to our hospital for reevaluation. One underwent further treatment in our centre, but with an unfavourable evolution. Pathologists should be aware of the diagnostic criteria for GNET in order to avoid misdiagnosis due to confusion with other non-epithelial gastrointestinal neoplasms.

Primary clear cell sarcoma of soft tissue in the posterior cervical spine invading the medulla oblongata: A case report

BACKGROUND

Clear cell sarcoma (CCS) is a rare and highly malignant soft tissue tumor, usually occurring in the deep soft tissues of the distal tendons and aponeurosis of the extremities, especially the feet and knees. CCS originating in the head and neck is extremely rare. The clinical manifestations of CCS in the head and neck are not typical, and the imaging manifestations have certain characteristics, but the diagnosis still depends on pathological examination and genetic testing.

CASE SUMMARY

A 33-year-old male patient had paroxysmal headache for more than 4 years, accompanied by nausea and vomiting, which could be relieved after rest. Computed tomography angiography showed a left paraspinal soft tissue mass. Contrast-enhanced imaging showed obvious uneven enhancement with adjacent bone lytic destruction. Magnetic resonance imaging examination showed isosignal on T₁-weighted images, slightly high signal on T₂-weighted images (T₂WI), high signal on Tirm fat suppression sequence, significantly high signal on diffusion weighted imaging, and obvious and uneven enhancement. The lesion invaded the anterior medulla oblongata through the left atlantoaxial foramen and compressed the cervical spinal cord on T₂WI. Primary CCS of soft tissue was diagnosed by pathology and genetic examination.

CONCLUSION

CCS should be considered in the differential diagnosis of soft tissue tumors of the head and neck, and their diagnosis depends on pathological examination and genetic testing.

Malignant Gastrointestinal Neuroectodermal Tumor: A New Kid on the Block?

ABSTRACT

Also referred to as "osteoclast-rich, clear cell sarcoma-like tumor of the gastrointestinal tract (CCSLGT)," malignant gastrointestinal neuroectodermal tumor is a newly described, rare, aggressive sarcoma that commonly arises in the small bowel, stomach, and colon. Histogenesis is likely from an autonomous nervous system-related primitive cell of neural crest origin. The hallmark genetic finding of EWS-CREB1 or EWS-ATF1 fusion transcripts clinches the diagnosis. Annular constrictive lesions tend to be smaller, show homogenous contrast enhancement on computed tomography, and may present with bowel obstruction. Larger, expansile masses tend to be exophytic and show heterogeneous contrast enhancement. Surgical resection is the mainstay of treatment. Frequent recurrences, metastases, and death from disease in 75% of patients portend a poor prognosis. Targeted chemotherapy based on specific tumor pathways is being developed.

Postoperative multiple metastasis of clear cell sarcoma-like tumor of the gastrointestinal tract in adolescent: A case report

BACKGROUND

Clear cell sarcoma-like tumor of the gastrointestinal tract (CCSLGT) is a rare malignant gastrointestinal mesenchymal soft tissue tumor. Its genetic feature is EWSR1 gene rearrangement. Histologically, it is often accompanied by a varying number of CD68-positive osteoclast-like giant cells. CCSLGT mostly occurs in the small intestinal wall of young people and children. In terms of clinical manifestations, there is no significant difference between it and other gastrointestinal tumors, and the diagnosis depends on immunohistochemistry and gene detection.

CASE SUMMARY

A 16-year-old man developed dizziness and fatigue 2 mo ago, and 10 d ago showed progressive exacerbation of paroxysmal epigastric pain and stopped flatulence and defecation. Computed tomography showed a soft tissue mass in the distal ileum. After complete resection of the lesion, it was diagnosed by combined immunohistochemical and genetic examination as CCSLGT. After surgery, the patient gradually developed lymph node, liver, lung, bone, left thigh, pleura and adrenal metastasis. The survival time was 4 years and 8 mo.

CONCLUSION

Whole abdominal computed tomography enhancement is recommended for patients with gastrointestinal symptoms. There is no effective treatment for CCSLGT with multiple metastases via the lymphatic system and bloodstream after surgical resection.

Malignant gastrointestinal neuroectodermal tumor presenting with small intestinal obstruction: A case report

Malignant gastrointestinal neuroectodermal tumors (GNETs) are rare malignant mesenchymal neoplasms. To our knowledge, only 99 cases have been reported worldwide. The tumor has an aggressive malignancy, with a rapid progression. The histological features of GNET overlap with those of clear cell sarcoma, which contain Ewing sarcoma breakpoint region 1 mutation. GNETs lack melanocyte‐specific markers, while clear cell sarcoma exhibits melanocytic differentiation. Various symptoms have been reported previously, and the most reported lesion is in the small bowel. The patient was a 69‐year‐old man who presented with abdominal pain and vomiting. Computed tomography revealed a nodule in the small bowel, which induced small intestinal obstruction. Enteroscopic images revealed a submucosal tumor. Surgery was performed, and the patient was diagnosed with GNET. Only two patients whose primary lesions were in the small intestine, including the patient in this report, have undergone enteroscopy before surgery. This is a rare case of GNET in which a patient underwent enteroscopy before surgical treatment.

Clinical, pathological, and genetic profile of clear cell sarcoma-like tumour of jejunum: report of a rare aggressive tumour of small bowel

Clear cell sarcoma-like tumour of the gastrointestinal tract (CCSLGT) is a rare entity which has been recently described as late as 2003. Only around 70 cases have been reported in the English literature till date. CCSLGT is mostly seen in young adults in the late 20 s and early 30 s. CCSLGT are aggressive tumours. They are similar to the clear cell sarcoma of the soft tissue but lack melanocytic differentiation, retain neuroendocrine differentiation, and have osteoclastic giant cells. EWSR1-CREB1 fusion is characteristic of these tumours. Complete surgical excision is the best treatment option available. They have a high recurrence rate and poor prognosis. Currently, effective chemotherapy or a targeted agent is not available for the management of these tumours. Here, we describe a case of clear cell sarcoma-like tumour of jejunum encountered by us in a young man. The immunohistochemical and genetic profiling of these tumours are also discussed.

Malignant Gastrointestinal Neuroectodermal Tumor in the Right Heart: A Report of an Extremely Rare Case Presenting With a Cardiac Mass

Malignant gastrointestinal neuroectodermal tumor (GNET) is an extremely rare soft tissue sarcoma and has been designated as a new entity recently. At present, GNET virtually exclusively occurs in the gastrointestinal tract. Here we report a case of extra-GNET that arose in the right heart. A 62-year-old male complained of chest distress and breathing difficulty while lying down at night for over 1 month at admission. The radiological findings revealed an occupying lesion involving the right atrium and the right ventricle without any abdominal abnormalities. The patient then underwent a surgical resection. Microscopically, neoplastic cells proliferated in the pattern of nests and sheets with fibrous separation. Focal areas with cellular dyscohesion imparted a vague pseudopapillary pattern. These tumor cells were small to medium in size with fine chromatin and predominantly pale eosinophilic cytoplasm. The nuclei were typically round to oval with somewhat irregular contours and contained small nucleoli. The mitotic figures were easily found. Immunohistochemically, the neoplastic cells were positive for S100 and SOX-10 but negative for HMB-45, A103, and CD99. EWSR1-AFTF1 rearrangement was detected by fluorescence in situ hybridization and further confirmed by whole-transcriptome sequence analysis. The patient had pulmonary metastasis 8 months later and soon died of the disease. The overall survival of the patient was 20 months. In summary, we reported an extremely rare case of cardiac GNET, indicating that the location of GNET should not be confined to the GI tract as initially defined. Due to the lack of a specific effective treatment and the occurrence of early metastasis, cardiac GNET conferred a poor prognosis. More clinical and experimental studies are warranted to better manage this disease in the future.

EWSR1-The Most Common Rearranged Gene in Soft Tissue Lesions, Which Also Occurs in Different Bone Lesions: An Updated Review

EWSR1 belongs to the FET family of RNA-binding proteins including also Fused in Sarcoma (FUS), and TATA-box binding protein Associated Factor 15 (TAF15). As consequence of the multifunctional role of EWSR1 leading to a high frequency of transcription of the chromosomal region where the gene is located, EWSR1 is exposed to aberrations such as rearrangements. Consecutive binding to other genes leads to chimeric proteins inducing oncogenesis. The other TET family members are homologous. With the advent of widely used modern molecular techniques during the last decades, it has become obvious that EWSR1 is involved in the development of diverse benign and malignant tumors with mesenchymal, neuroectodermal, and epithelial/myoepithelial features. As oncogenic transformation mediated by EWSR1-fusion proteins leads to such diverse tumor types, there must be a selection on the multipotent stem cell level. In this review, we will focus on the wide variety of soft tissue and bone entities, including benign and malignant lesions, harboring EWSR1 rearrangement. Fusion gene analysis is the diagnostic gold standard in most of these tumors. We present clinicopathologic, immunohistochemical, and molecular features and discuss differential diagnoses.

Rationale for Early Detection of EWSR1 Translocation-Associated Sarcoma Biomarkers in Liquid Biopsy

Sarcomas are mesenchymal tumours that often arise and develop as a result of chromosomal translocations, and for several forms of sarcoma the EWSR1 gene is a frequent translocation partner. Sarcomas are a rare form of malignancy, which arguably have a proportionally greater societal burden that their prevalence would suggest, as they are more common in young people, with survivors prone to lifelong disability. For most forms of sarcoma, histological diagnosis is confirmed by molecular techniques such as FISH or RT-PCR. Surveillance after surgical excision, or ablation by radiation or chemotherapy, has remained relatively unchanged for decades, but recent developments in molecular biology have accelerated the progress towards routine analysis of liquid biopsies of peripheral blood. The potential to detect evidence of residual disease or metastasis in the blood has been demonstrated by several groups but remains unrealized as a routine diagnostic for relapse during remission, for disease monitoring during treatment, and for the detection of occult, residual disease at the end of therapy. An update is provided on research relevant to the improvement of the early detection of relapse in sarcomas with EWSR1-associated translocations, in the contexts of biology, diagnosis, and liquid biopsy.

Intracranial angiomatoid fibrous histiocytoma with rhabdoid features: a mimic of rhabdoid meningioma

Angiomatoid fibrous histiocytoma (AFH) is an uncommon soft-tissue neoplasm that arises mostly in the extremities of young people and generally carries a good prognosis. Intracranial location is unusual and frequently associated with myxoid change. EWSR1 gene fusions with members of the CREB family (CREB1, ATF1, and CREM) are well-established events in AFH. These fusions have also been described in other neoplasms including intracranial myxoid mesenchymal tumor, and it is still uncertain whether the latter is a distinct entity or if it represents a myxoid variant of AFH. Here, we describe a rare falcine AFH presenting in a 50-year-old woman. The most striking feature of this tumor was its diffuse rhabdoid morphology with focal high mitotic activity, raising the consideration of rhabdoid meningioma (WHO grade III). The tumor cells were moderately positive for EMA and negative for progesterone receptor and SSTR2 prompting additional studies. Desmin was strongly positive and CD99 showed membranous immunoreactivity. BAP1, INI-1, and BRG1 expressions were retained. Next-generation sequencing analysis demonstrated an EWSR1-ATF1 gene fusion, supporting the diagnosis of an unusual rhabdoid variant of AFH. After gross total resection of this tumor, the patient remains free of disease 5 months after the surgery without additional treatment.

Primary Clear Cell Sarcoma of the Ileum: A Case Report With Next-Generation Sequencing Analysis

As the concept of clear cell sarcoma-like tumor or malignant gastrointestinal neuroectodermal tumor (CCS-LT/MGNET) has been widely accepted, primary CCS of the gastrointestinal tract (CCS-GI) is becoming a rare entity. In this article, we describe a case of primary CCS-GI that occurred in the ileum of a 65-year-old male to further illustrate its rare occurrence. Similar to CCS of soft tissue (CCS-ST), the tumor was composed of spindled to epithelioid cells displaying fascicular, nested, or pseudopapillary arrangement. The tumor cells had large round to ovoid nuclei with vesicular chromatin and prominent nucleoli, containing eosinophilic to pale cytoplasm. In contrast to CCS-LT/MGNET, immunohistochemical study also showed variable positivity of HMB45, melan A, and MiTF besides the strong and diffuse staining of S100 protein and SOX10. Fluorescence in situ hybridization (FISH) using fusion probes identified EWSR1 and ATF1 genes rearrangement. Next-generation sequencing (NGS) analysis further revealed EWSR1 exons9/8-ATF1 exon4 and ATF1 exon3- EWSR1 exon11 fusion genes. CCS-GI and CCS-LT/MGNET possibly represent 2 related entities of the same spectrum, which differentiate along 2 different pathways.

Fine Needle Aspiration Cytology of Malignant Digestive System Gastrointestinal Neuroectodermal Tumor in a Lymph Node Metastasis from a Previously Diagnosed Liver Primary: A Case Report and Review of Literature

Malignant gastrointestinal neuroectodermal tumor (GNET) is an extremely rare neoplasm. Immunohistochemically, GNET typically demonstrates neural differentiation but lacks melanocytic differentiation, making it distinct from clear cell sarcoma of the soft tissues (CCS). Herein we report for the first time the cytomorphologic features of lymph node metastasis from presumably liver GNET. A 36-year-old female presented with fevers, night sweats, loss of appetite, and a 20-lbs weight loss. Radiographic imaging showed a 13 cm heterogeneously enhancing mass in the right lobe of the liver and a hypermetabolic 0.9 cm periportal lymph node on positron emission tomography-computed tomography (PET/CT). Initially, a CT-guided liver biopsy was performed followed by right hepatic lobectomy and portal lymphadenectomy. The liver biopsy and resection showed an S100-protein and SOX10 positive malignant neoplasm and genomic profiling of liver biopsy revealed EWSR1-CREB1gene rearrangement. These findings in conjunction with the morphologic and immunohistochemical profile were diagnostic of GNET. Two months later, she presented with recurrent lymphadenopathy in the upper abdomen. Fine needle aspiration of the periportal nodal mass revealed single and clusters of primitive, large to medium-sized neoplastic cells with round to oval nuclei, high nuclear-cytoplasmic ratio, vesicular chromatin, and prominent nucleoli. The tumor cells were S100 protein and SOX10 positive, consistent with metastasis of the patient's recently diagnosed malignant digestive system GNET. Palliative chemotherapy was administered but the patient died a few days later, 4 months from the initial diagnosis. Awareness of this entity and judicial use of ancillary studies including molecular testing are essential for achieving accurate diagnosis.

Systemic treatment of malignant gastrointestinal neuroectodermal tumour after childhood neuroblastoma: chemotherapy in malignant gastrointestinal neuroectodermal tumour

Malignant gastrointestinal neuroectodermal tumour is an extremely rare neoplasm that arises in the wall of the small bowel, stomach or large bowel in young-aged and middle-aged adults. Histologically, it is generally characterized by monomorphic cells with clear cytoplasma, S-100 protein expression, and EWSR1 gene translocation. To the best of our knowledge, we describe for the first time, the case of a young woman with a diagnosis of metastatic gastrointestinal neuroectodermal tumour arising from ileum, who had a childhood adrenal neuroblastoma with liver, bone and lymph nodes metastasis, treated with four cycles of chemotherapy with the schedule CADO-CVP (CADO: cyclophosphamide 300 mg/m/day on days 1-5, vincristine 1,5 mg/m/day on days 1 and 5, and doxorubicin 60 mg/m/day on day 5; CVP: cisplatin 40 mg/m/day on days 1-5 and etoposide 100 mg/m/day on days 1-5) followed by right adrenal, kidney, lymph nodes and liver lesion resection, conditioning chemotherapy (melphalan-carmustine-teniposide), stem cells autologous transplantation and consecutively radiotherapy on the spine (T9 to L3) for a total of 30 Gy. For the second diagnosis of gastrointestinal neuroectodermal tumour with liver metastasis, she underwent ileal tumour resection and platinum-anthracycline based chemotherapy with initial shrinkage of liver metastasis. Unfortunately, despite the initial response and the following delivered therapies, she died for rapid progressive disease. Taking into account the late effects of past therapeutic modalities, a long-term surveillance of young child treated for neuroblastoma, is required to appreciate their overall risks of second malignancies.

Surgically treated gastric melanoma of unknown primary: A case report from a 10-year survivor

We describe an extremely rare case of simultaneous double melanoma of the stomach with no other obvious primary source. The patient has survived for more than 12 years post-complete gastrectomy. The patient was a woman in her seventies who was referred for anemia by another clinic. Esophagogastroscopy revealed an ulcerated gastric tumor that was diagnosed as a gastrointestinal stromal tumor (GIST) by endoscopic biopsy. She was admitted to our hospital for further examination and treatment. Gastroscopy at our institution revealed two submucosal tumors in the gastric wall. Since no metastatic lesions were detected after systemic exploration, multiple GIST of the stomach was diagnosed, and a total gastrectomy was performed. Malignant melanoma was diagnosed in both lesions by a histopathological study of the resected stomach. The patient's postoperative progress was good, and thorough examination of the skin did not result in the discovery of any systemic neoplastic lesions which could be regarded as the source for the primary tumor. No anticancer treatments were used. The patient has survived, with no recurrence for over ten years postsurgery. Strong evidence is presented in this case for the diagnosis and treatment of gastric malignant melanoma.

Malignant Gastrointestinal Neuroectodermal Tumor: Clinicopathologic, Immunohistochemical, and Molecular Analysis of 19 Cases

A malignant gastrointestinal neuroectodermal tumor (GNET) is rare, and it is therefore yet to be completely understood. This study aimed to present the clinicopathologic features of GNET, including treatment information. We included 19 patients with GNET with a mean tumor size of 4.2 cm. The most common site of tumor origin was the small intestine (57.9%), followed by the stomach (15.8%), colon (10.5%), ileocecal junction (5.3%), lower esophagus (5.3%), and anal canal (5.3%). Microscopically, the tumors were composed of epithelioid cells with eosinophilic or clear cytoplasm arranged in nest, sheet-like, papillary, or pseudoalveolar patterns and/or spindle tumor cells with eosinophilic cytoplasm arranged in a fascicular pattern. Immunohistochemically, the tumor cells stained positively for S100 (19/19,100%), SOX10 (14/15, 93.3%), vimentin (17/17, 100%), synaptophysin (Syn) (7/17, 41.2%), CD56 (4/13, 30.8%), CD99 (1/5, 20%), and CD117 (1/15, 6.7%), and negatively for HMB45, Melan A, DOG1, CD34, AE1/AE3, CAM5.2, chromogranin A, smooth muscle actin, and desmin. In total, 14/15 (93.3%) cases showed split Ewing sarcoma breakpoint region 1 gene (EWSR1) signals consistent with a chromosomal translocation involving EWSR1. Within a mean follow-up of 29.7 months (range: 3 to 63 mo), 2/15 (13.3%) patients died of disease, 5 (33.3%) were alive with disease, and 8 (53.3%) had no evidence of disease. Two and 1 patients showed partial response to apatinib and anlotinib, respectively. In conclusion, GNET has distinctive morphologic, immunohistochemical, and molecular genetic features and should be distinguished from other gastrointestinal tract malignancies. Apatinib and anlotinib might be effective for the treatment of advanced GNET and could prolong patient survival.

Clear cell sarcoma of the esophagus: A rare location

Clear cell sarcoma of the esophagus is very rare. The etiology of this neoplasm remains unknown. Confirmed diagnosis requires histopathology with immunochemistry and molecular study. CCS typically shows highly aggressive behavior with a high rate of local recurrence, metastases, and death from disease.

Primary malignant gastrointestinal neuroectodermal tumor occurring in the ileum with intra-abdominal granulomatous nodules: A case report and review of the literature

Malignant gastrointestinal neuroectodermal tumors (GNETs) are rare aggressive malignant neoplasms that exclusively occur within the wall of the gastrointestinal tract. The GNET was first described as an ‘osteoclast-rich tumor of the gastrointestinal tract with features resembling clear cell sarcoma (CCS) of soft parts’ in 2003. Although the GNET shares certain histological features with CCS, it is characterized by a lack of melanocytic differentiation and the presence of non-tumoral osteoclast-like giant cells (OLGCs). The present study reports a case of a GNET of the ileum with intra-abdominal granulomatous nodules, an uncommon accompanying finding, and summarizes the current literature. A 30-year-old woman presented with the symptoms of intestinal obstruction, and a mass was found within the ileum wall. Multiple grey-white nodules were found adhering to the omentum and serosa of the ileum. Histologically, the tumor was located in the muscularis propria and infiltrated the mucosa and the serosa. Tumor cells presented with oval or polygonal nuclei and prominent nucleoli, and were predominantly arranged in nested and pseudopapillary patterns, with the presence of cluster of differentiation (CD)68-positive, scattered OLGC. Immunohistochemically, it was determined that the tumor cells expressed Vimentin, CD56, S-100 and transcription factor SOX-10, while being negative for pan-cytokeratin, cytokeratin (CK)7, CK20, synaptophysin, chromogranin-A, CD117, anoctamin-1, CD34, human melanoma black-45, Melan-A, smooth muscle actin, CD3 and CD20 expression. Ewing sarcoma breakpoint region 1 gene rearrangement was identified by fluorescence in situ hybridization analysis. Ultrastructurally, no typical melanosomes were identified. In addition, the intra-abdominal grey-white nodules were microscopically identified as chronic granulomatous inflammation. The patient received four cycles of adjuvant chemotherapy following routine tumor resection. Due to its rarity and histological similarity with other neoplasms, unfamiliarity with the features of GNETs by surgical pathologists can easily lead to a misdiagnosis. Therefore, comprehensive assessments, including morphology and ancillary studies, are required for an accurate diagnosis of GNET.

[Clear cell sarcoma or gastrointestinal neuroectodermal tumor (GNET) of the tongue? Case report and review of the literature of an extremely rare tumor localization]

Clear cells sarcomas (CCS) are exceptionally rare in the tongue, with, to our knowledge, only three previous reports in anglo-saxon literature. Through our case, we will discuss the differential diagnosis of clear cells tumors of the tongue and bring this tumour closer to the newly described entity of the gastrointestinal tract named "clear cells sarcoma-like gastrointestinal (SCCLGI)", recently renamed "gastrointestinal neuroectodermal tumour (GNET)". SCCLGI/GNET share morphological and molecular characteristics with SCC but had until then been observed only in the digestive tract. Our case could be a lingual localization of a SCCLGI/GNET. SCC and SCCLGI/GNET characteristic molecular profil involves EWSR1-ATF1 [t(12; 22) (q13; q12)] and EWSR1-CREB1 [t(2; 22) (q34; q12)] fusion genes, but it is not specific of these tumours.

Detection of specific gene rearrangements by fluorescence in situ hybridization in 16 cases of clear cell sarcoma of soft tissue and 6 cases of clear cell sarcoma-like gastrointestinal tumor

Background

Clear cell sarcoma of soft tissue (CCSST) and clear cell sarcoma-like gastrointestinal tumor (CCSLGT) are malignant mesenchymal tumors that share some pathological features, but they also have several different characteristics. They are well known to express chimeric fusions of Ewing sarcoma breakpoint region 1 (EWSR1) and cAMP response element-binding protein (CREB) family members; namely, EWSR1-activating transcription factor 1 (ATF1) and EWSR1-CREB1. In addition, recent studies have suggested the presence of other fusions.

Methods

We used fluorescence in situ hybridization to detect specific rearrangements including EWSR1, ATF1, CREB1, and cAMP response element modulator (CREM) in 16 CCSST and 6 CCSLGT cases. We also used reverse transcription polymerase chain reaction (RT-PCR) to detect specific chimeric fusions of EWSR1-ATF1 and EWSR1-CREB1 using fresh tumor samples in available cases.

Results

A total of 15 of 16 CCSST cases (93.8%) had EWSR1 rearrangement, of which 11 (68.8%) also had ATF1 rearrangement, suggestive of the presence of EWSR1-ATF1 fusions. One CCSST case (6.3%) was found to have EWSR1 and CREM rearrangements, and 4 of 6 CCSLGT cases (66.7%) had EWSR1 rearrangement, of which 2 (33.3%) showed ATF1 rearrangement and the other 2 cases (33.3%) showed CREB1 rearrangement. These cases most likely had EWSR1-ATF1 and EWSR1-CREB1 fusions, respectively. RT-PCR was performed in 8 available cases, including 6 CCSSTs and 2 CCSLGTs. All CCSSTs showed EWSR1-ATF1 fusions. Among the 2 CCSLGT cases, one had EWSR1-ATF1 fusion and the other had EWSR1-CREB1 fusion.

Conclusions

Rearrangements of EWSR1 and ATF1 or EWSR1-ATF1 fusion were predominantly found in CCSST, whereas those of EWSR1 and CREB1 or EWSR1-CREB1 tended to be detected in CCSLGT. A novel CREM fusion was also detected in a few cases of CCSST and CCSLGT. The cases in which EWSR1 rearrangement was detected without definitive partner genes should be considered for the presence of CREM rearrangement.

Clear cell sarcoma of the gastrointestinal tract and malignant gastrointestinal neuroectodermal tumour: distinct or related entities? A review

Clear cell sarcoma is an uncommon sarcoma which rarely occurs as a primary tumour in the gastrointestinal tract (CCS-GIT). It shares common molecular genetic abnormalities with the more recently described entity, malignant gastrointestinal neuroectodermal tumour (GNET) but is distinguished by its morphological and immunohistochemical findings. The exact nosological relationship between these tumours continues to be debated. In this review, we present two cases of these rare neoplasms from our files and perform a statistical comparison of all published cases to determine if significant differences exist in their clinicopathological features and biological behaviour. Thirteen cases of CCS-GIT and 58 of GNET were included. CCS-GIT occurred more commonly in males (84.6% vs 46.6%, p = 0.01) and in an older age group (median 57 vs 33 years, p < 0.01). There was no significant difference in their location in the gastrointestinal tract, median tumour size and proportion of cases with an EWSR1-ATF1 vs EWSR1-CREB1 fusion. Median survival for CCS-GIT was 13.5 months and for GNET, 9.5 months (p = 0.78). There was no significant difference in the Kaplan-Meier survival curves for either time to first metastasis (p = 0.88) or overall survival (p = 0.18), including after controlling for tumour size using regression models. Our analysis confirms that aside from morphological variations between these tumours, they also exhibit epidemiological and clinical differences. Despite the prevalent perception that GNET is associated with a more aggressive clinical course, our findings indicate that there is no significant difference in their biological behaviour, although both clearly share a bleak prognosis. Further experience is awaited to determine optimal treatment strategies and whether CCS-GIT and GNET would differ in their response to various therapies.

Practical Immunohistochemistry in Neoplastic Pathology of the Gastrointestinal Tract, Liver, Biliary Tract, and Pancreas

CONTEXT

- Immunomarkers with diagnostic, therapeutic, or prognostic values have been increasingly used to maximize the benefits of clinical management of patients with neoplastic diseases of the gastrointestinal tract, liver, biliary tract, and pancreas.

OBJECTIVES

- To review the characteristics of immunomarkers that are commonly used in surgical pathology practice for neoplasms of the gastrointestinal tract, liver, biliary tract, and pancreas, and to summarize the clinical usefulness of immunomarkers that have been discovered in recent years in these fields.

DATA SOURCES

- Data sources include literature review, authors' research data, and personal practice experience.

CONCLUSIONS

- Immunohistochemistry is an indispensable tool for the accurate diagnosis of neoplastic diseases of the gastrointestinal tract, liver, biliary tract, and pancreas. Useful immunomarkers are available to help distinguish malignant neoplasms from benign conditions, determine organ origins, and subclassify neoplasms that are morphologically and biologically heterogeneous. Specific immunomarkers are also available to help guide patient treatment and assess disease aggressiveness, which are keys to the success of personalized medicine. Pathologists will continue to play a critical role in the discovery, validation, and application of new biomarkers, which will ultimately improve patient care.

Imprint cytology of clear cell sarcoma-like tumor of the gastrointestinal tract in the small intestine: A case report

Clear cell sarcoma-like tumor of the gastrointestinal tract (CCSLGT) is an extremely rare malignant neoplasm in the digestive tract. Its cytomorphologic features have never previously been reported. Here, we describe a case of CCSLGT, including its cytologic examination findings. A 47-year-old woman presented with a mass in the small intestine, which was resected and sent for imprint cytology. Imprint smears revealed tumor cells with light eosinophilic or clear cytoplasm in a necrotic background. Many of the tumor cells were arranged in a perivascular growth with a pseudopapillary formation, and there were some non-neoplastic osteoclast-like giant cells. Histological examination revealed solid nests and a pseudopapillary pattern of the tumor cells with clear or pale eosinophilic cytoplasm and large nuclei with small nucleoli. Immunohistochemistry showed positive for vimentin, S-100, and SOX-10, and negative for SMA, c-KIT, cytokeratin, HMB-45, and MelanA. The EWSR1 gene split signal was detected by reverse transcriptase fluorescence in situ hybridization, and EWSR1-CREB1 gene fusion was indicated by reverse transcriptase polymerase chain reaction analysis. From these findings, we diagnosed the tumor as CCSLGT. To best of our knowledge, this is the first description of the imprint cytology features of CCSLGT.