Malignant Gastrointestinal Neuroectodermal Tumor: a Unique Rare Neoplasm

A peculiar mimicker of gastro-entero-pancreatic neuroendocrine tumors: Malignant Gastrointestinal Neuroectodermal Tumor - literature review and one case report

Malignant gastrointestinal neuroectodermal tumor (GNET) is a distinctive and relatively newly described neoplasm that is seldom encountered in routine clinical practice. It is characterized by a predominantly monomorphic population of polyhedral to epithelioid cells, exhibiting pale eosinophilic or clear cytoplasm, rounded nuclei with vesicular chromatin, and occasionally prominent eosinophilic nucleoli. These cells are arranged in a heterogeneous pattern, forming small nests, compact solid areas, and pseudo-papillary or pseudo-microcystic structures. Within the tumor, osteoclast-like giant cells may be a notable feature, although their presence is variable. This tumor consistently demonstrates positivity for S100, SOX10, and vimentin, while it is invariably negative for Melan-A, HMB45, desmin, CD117, and pan-cytokeratin. Additionally, it exhibits variable expression of the following immunohistochemical markers: synaptophysin, chromogranin, CD56, neuron-specific enolase (NSE), and neurofilament protein (NFP). A specific mutation in the Ewing's sarcoma breakpoint region 1 (EWSR1) gene has been described for GNET, characterized by EWSR1-CREB1 and EWSR1-ATF1 fusions. This article discusses the clinical, pathological, immunophenotypic, and genetic features of one clinical case of GNET, followed by a literature review of 127 cases published in the PubMed database, for which full-length articles were accessible. According to this review, approximately 10% of GNETs have been initially misdiagnosed, with about 6% being misclassified as neuroendocrine tumors or neuroendocrine carcinomas.

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.

Malignant Gastrointestinal Neuroectodermal Tumor of Small Intestine Showing DOG1 Expression: A Case Report and Review of Literature

Malignant gastrointestinal neuroectodermal tumor (GNET), also referred to as clear cell sarcoma-like tumor of the GI tract is a rare mesenchymal tumor of the gastrointestinal tract. It has to be distinguished from various mimickers including gastrointestinal stromal tumor (GIST) due to its aggressive course and different natural history and therapeutic approach. Here we report a case of GNET arising in the small intestine with aberrant DOG1 expression posing a diagnostic challenge. In this context, the combination of clinical, histomorphological, immunohistochemical, and molecular features helped to establish a proper diagnosis.

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.

[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.

A Case Series of Metastatic Malignant Gastrointestinal Neuroectodermal Tumors and Comprehensive Genomic Profiling Analysis of 20 Cases

Malignant gastrointestinal neuroectodermal tumor (GNET) is an ultra-rare soft tissue sarcoma, therefore often misdiagnosed and has no available standard treatment. Here, we report 3 cases of metastatic GNET with variable clinical courses. Our small case series as well as extensive literature review, further support that GNET is a spectrum of diseases with variable inherent biology and prognosis. Surgical management in the setting of recurrent/metastatic disease may be appropriate for GNET with indolent nature. Response to systemic treatments including chemotherapy and targeted treatments is variable, likely related to heterogenous biology as well. Furthermore, we retrospectively identified 20 additional GNET cases from Foundation Medicine’s genomic database and expanded on their clinicopathological and genomic features. Comprehensive genomic profiling (CGP) with DNA and RNA sequencing of this cohort, in the course of clinical care, demonstrated recurrent EWSR1 chromosomal rearrangements and a sparsity of additional recurrent or driver genomic alterations. All cases had low tumor mutational burden (TMB) and were microsatellite stable.

Malignant Gastrointestinal Neuroectodermal Tumor (GNET) with Prolonged Disease-Free Survival after Platinum-Based Chemotherapy

Malignant gastrointestinal neuroectodermal tumor (GNET) is a rare disease with a handful of cases described in literature. GNET has only become a well-known/widely accepted entity in the recent years, but it is still not listed in the database of rare diseases. Due to the rarity of disease, there are no guidelines on standard therapeutic approaches in the adjuvant or metastatic setting. Here, we describe a unique case of GNET with a 7-year disease-free survival following adjuvant cisplatin and etoposide chemotherapy. This is the longest disease-free survival that has ever been described in literature and may support using this combination in a larger cohort of patients in the context of a global clinical trial. We will also review the histopathologic features of GNET and potential therapeutic options in the metastatic setting.

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.

Oral malignant gastrointestinal neuroectodermal tumour with junctional component mimicking mucosal melanoma

Malignant gastrointestinal neuroectodermal tumour (GNET) is a recently characterised rare and aggressive tumour that typically arises in association with the small intestine of adults. We present a novel case of this entity and expand the spectrum of its reported morphological features. The patient was a 5-year-old female, the youngest reported patient affected by the condition, and presented with extra-abdominal disease. The histopathological features included the presence of a junctional component of the palatal tumour, which mimicked mucosal melanoma, a feature that has not been previously reported in GNET. Whole genome and RNA sequencing was performed that demonstrated the EWSR1-ATF1 translocation characteristic of GNET. Knowledge of this entity and its features, together with careful morphological assessment supplemented by judicious immunohistochemical and molecular studies should enable the correct diagnosis to be established.