Clear cell sarcoma of the stomach

Intestinal Clear Cell Sarcoma-A Case Presentation of an Extremely Rare Tumor and Literature Review

Background: Clear cell sarcoma (CCS) is an extremely rare form of sarcoma representing less than 1% of all soft-tissue sarcomas. It has morphological, structural, and immunohistochemical similarities to malignant melanoma, affecting young adults and equally affecting both sexes, and is usually located in the tendinous sheaths and aponeuroses of the limbs. Gastrointestinal localization is exceptional, with less than 100 cases reported thus far. The gene fusion of activating transcription factor 1 (ATF1) and the Ewing sarcoma breakpoint region 1 (EWSR1) are pathognomonic for clear cell sarcoma, representing the key to the diagnosis. CCS is an extremely aggressive tumor, with >30% having distant or lymphatic metastasis at the time of diagnostic, and it has a high recurrence rate of over 80% in the first year after diagnosis and a high tendency for metastatic dissemination. Given the rarity of this tumor, there is no standardized treatment. Early diagnosis and radical surgery are essential in the treatment of CCS both for the primary tumor and for recurrence or metastasis. Chemo-radiotherapy has very little effect and is rarely indicated, and the role of targeted therapies is still under investigation. Case presentation: We present an extremely rare case of intestinal CSS in a 44-year-old Caucasian female. The patient, asymptomatic, first presented for a routine checkup and was diagnosed with mild iron-deficiency anemia. Given her family history of multiple digestive cancers, additional investigations were requested (gastroscopy, colonoscopy, tumoral markers and imaging) and the results were all within normal limits. In the subsequent period, the patient experienced mild diffuse recurrent abdominal pain, which occurred every 2-3 months. Two years later, the patient presented with symptoms of intestinal obstruction and underwent an emergency laparotomy followed by segmental enterectomy and regional lymphadenectomy for stenotic tumor of the jejunum. Histology, immunohistochemistry, and genetic testing established the diagnosis of CCS. No adjuvant therapy was indicated. Initially, no signs of recurrence or metastasis were detected, but after 30 and 46 months, respectively, from the primary treatment, the patient developed liver metastasis and pericolic peritoneal implants treated by atypical hepatic resections and right hemicolectomy. The patient remains under observation.

Gastric cancer in the pediatric population, a multicenter cross-sectional analysis of presentation and coexisting comorbidities

OBJECTIVES

Solid tumors of the stomach in children are rare, adenocarcinoma being most frequently reported. Risk factors and clinical presentation are poorly understood. We undertook a nationwide database analysis to evaluate pediatric CA stomach presentation, comorbidities, and metastatic pattern.

METHODS

The Cerner Health Facts Database^® (CHFD) was queried for pediatric age range (1-21) patients, 2010-2017 inclusive. The pediatric gastric cancer cohort was defined by ICD9 and ICD 10 CM diagnoses attributable to primary (non-GIST, non-hematologic) solid tumors of the stomach limited to diagnosis priority < 5 and validated by filtering for supportive diagnoses. Demographic characteristics, comorbidities, before and throughout the medical record were analyzed and compared to the base population.

RESULTS

The cohort included 333 patients from a base population of 9.6 million children. The M:F ratio was 1.15:1, mean age at diagnosis was 11.8 years. Stomach cancer was most prevalent in non-Hispanic whites, less in Asians and African Americans. Symptoms included abdominal pain, vomiting, anemia, diarrhea and weight loss. Reflux symptoms, esophagitis, gastritis, including H. pylori and duodenitis were reported in 10.2%. Obesity, obesity-related comorbidities, tobacco exposure and family history of colonic polyps, gastrointestinal and breast cancer were all more prevalent (P < 0.0001) in the cohort.

DISCUSSION

We defined patient demographic characteristics, anatomic distribution in a large cohort of children with solid tumors of the stomach. Reported symptoms in our cohort are similar to those observed in adults. Associated comorbidities which may reflect risk factors include obesity, tobacco exposure and family history of intestinal polyps and malignancy.

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.

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.

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.

Malignant Gastrointestinal Neuroectodermal Tumor: a Unique Rare Neoplasm

Malignant gastrointestinal neuroectodermal tumor (GNET) is a rare malignant tumor. It is also referred to as clear cell sarcoma-like gastrointestinal tumor (CCSLGT). It is an aggressive tumor with a high rate of local recurrence, metastases, and early death from disease. Its pathogenesis is not known. It shows evidence of neural differentiation and lacks immunohistochemical and ultrastructural evidence of melanocytic differentiation. It needs to be distinguished from various mimickers owing to its aggressive course. Herein, we report a case of GNET in a 55-year-old female patient.

Multiple clear-cell sarcomas of small intestine with parotid gland metastasis: A case report

Clear-cell sarcoma is a rare, malignant soft tissue tumor that displays melanocytic differentiation with a distinct molecular profile. It is rarely localized in the gastrointestinal tract. Herein we reported a case of multiple synchronous clear-cell sarcomas of the gastrointestinal tract with parotid gland metastasis. A 51-year-old male patient presented with a growing painless mass under the right ear. A preoperative positron emission tomography/computed tomography showed multiple intestinal masses and a mass in the right parotid with increased glucose uptake, and he underwent operative treatment with resection of three tumors in the jejunum and ileum and then received a right parotidectomy. Postoperative pathological examination showed that cells in the intestinal tumor were consistent with clear-cell sarcoma of the gastrointestinal tract, and the malignant cells in the parotid gland were similar to the intestinal tumor. Immunohistochemical studies revealed positive expression of HMB-45, Melan-A, and S-100. EWSR1 gene fusion transcripts were undetectable by fluorescence in situ hybridization.

Malignant gastrointestinal neuroectodermal tumor: a case report and review of the literature

BACKGROUND

Malignant gastrointestinal neuroectodermal tumor (GNET) is an extremely rare entity that was first described by Zambrano et al. in 2003 as "Clear cell sarcoma-like tumor of the gastrointestinal tract". It shares some of the histological features of clear cell sarcoma (CCS) but lacks the immunohistochemical reactivity for melanocytic markers. We report a case of GNET that was initially misdiagnosed as gastrointestinal stromal tumor (GIST). Recognizing this entity is important to avoid misdiagnosis.

CASE PRESENTATION

A case of an 18-year-old male presented with a small intestinal tumor. Histologically it was characterized by polygonal cells arranged in pseudoalveolar pattern and situated in the muscularis propria. Scattered osteoclast-like multinucleated giant cells were also noted. The neoplastic cells were positive for S-100 protein and negative for HMB-45, Melan A, smooth muscle actin, desmin and CD117. EWSR1 gene rearrangement was detected by fluorescence in situ hybridization (FISH) analysis. The patient returned with recurrence after 36 months' management by surgical resection and died one year later.

CONCLUSIONS

GNET can be mistaken histologically for other non-epithelial gastrointestinal tumors. Awareness of its existence and diagnostic criteria by the pathologist is necessary to avoid misdiagnosis, particularly as GIST, CCS or malignant peripheral nerve sheath tumor (MPNST).

Simultaneous Clear Cell Sarcomas of the Duodenum and Jejunum

Clear cell sarcoma (CCS) is an uncommon tumor that usually presents as an extremity mass but can rarely manifest as a gastrointestinal tumor with a diverse spectrum of symptoms, most commonly related to a mass effect or ulceration. Herein we report a case in which two separate tumors, one in the duodenum and the other in the jejunum, present concurrently. The subject presented with symptomatic anemia and underwent imaging and endoscopic studies that culminated in the discovery of the two lesions. He subsequently underwent operative treatment with resection of both tumors and made an unremarkable recovery. The resection specimen consisted of two separate clear cell sarcomas with negative margins. Under microscopic evaluation, they demonstrated nested growths of epithelioid cells with scattered spindled cells infiltrating the enteric wall. The neoplastic cells were positive for S100 with scattered expression of Melan A. Florescence in situ hybridization revealed a translocation at the EWRS1 locus. He was disease-free for 30 months following the procedure; then he developed a rapidly progressing metastatic disease with subsequent death 4 months later.

Esophageal subepithelial lesion diagnosed as malignant gastrointestinal neuroectodermal tumor

A 21-year-old male visited our hospital with a complaint of aggravating dysphagia and odynophagia for a few days. Esophagogastroduodenoscopy showed huge bulging mucosa with an intact surface causing luminal narrowing at 35 cm from the incisor teeth. Endoscopic ultrasonography showed an about 35 mm sized irregular margined in-homogenous hypoechoic lesion with an obscure layer of origin. Endoscopic ultrasonography fine needle aspiration revealed spindle cell proliferation without immunoreactivity for CD117, SMA, and cytokeratin. The patient underwent excision of the subepithelial lesion at the distal esophagus. On pathologic examination of the specimen, the tumor was composed of short fascicles of oval to spindle cells with eosinophilic and clear cytoplasm and vesicular nuclei. The tumor cells were positive for S-100 and SOX10 and negative for CD117, SMA, HMB-45, melan-A, cytokeratin, and CD99. The split-apart signal was detected in EWSR1 on FISH, suggesting a malignant gastrointestinal neuroectodermal tumor. At the time of writing, the patient is on radiation therapy at the operated site of esophagus and doing well, with no recurrence for three months. Malignant gastrointestinal neuroectodermal tumor is a rare gastrointestinal tumor with features of clear cell sarcoma, without melanocytic differentiation, and shows a poor prognosis. This is the first reported case of malignant gastrointestinal neuroectodermal tumor arising as subepithelial lesion in the esophagus.

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

Clear cell sarcoma–like tumor of the gastrointestinal tract (CCSLGT) is a rare malignant neoplasm that occurs in the wall of the small bowel, stomach, or large bowel, predominantly in young adults. It is an aggressive neoplasm that frequently presents with metastatic disease and has a high mortality rate. Histologically, it is usually composed of medium-sized primitive ovoid or epithelioid cells with pale or clear cytoplasm that are arranged in sheets or in papillary or alveolar architectures. Clear cell sarcoma–like tumor of the gastrointestinal tract is positive for S100 protein, invariably negative for melanocyte-specific markers and is often also positive for neuroendocrine markers. The etiology of CCSLGT is unknown, but many studies have shown associations with EWSR1-CREB1 gene fusions and, less frequently, with EWSR1-ATF1 fusions. Here, we discuss the current status of CCSLGT, including histologic, immunophenotypic, and molecular findings.

Malignant gastrointestinal neuroectodermal tumor: A case report and review of the literature

Malignant gastrointestinal neuroectodermal tumor (GNET) is a rare soft tissue sarcoma, previously referred to as clear cell sarcoma-like gastrointestinal tumor (CCSLGT) and also commonly reported in the literature as clear cell sarcoma of the gastrointestinal tract (CCS-GI). The current study reports a case of GNET arising in the stomach of a 17-year-old male, who presented with symptoms of fatigue, anemia and low temperature. Examination with positron emission tomography-computed tomography revealed a soft tissue mass in the gastric antrum. Subsequently, radical distal gastric resection was performed, and the mass measured 6.0×4.0×3.5 cm³. Histopathological analysis revealed that the tumor cells were arranged in nests and focally formed fascicular, pseudopapillary, pseudoalveolar and rosette-like growth patterns. Osteoclast-like giant cells were also observed. Immunohistochemically, the tumor cells were positive for S-100 protein, vimentin and BCL-2, and negative for HMB45, Melan-A, CD117, CD34 and CD99. Additionally, the osteoclast-like giant cells were positive for CD68. Fluorescence in situ hybridization demonstrated EWSR1 gene rearrangement. After 10 months of follow-up, no evidence of recurrence or metastasis was observed. As GNET is currently classified differently and under various names in the literature, the information provided by this case study and review is predicted to be useful towards the accurate diagnosis, treatment and prognosis of this rare tumor type.

Clear Cell Sarcoma–Like Tumor of the Gastrointestinal Tract

Clear cell sarcoma is a rare tumor classically associated with tendons and aponeuroses of lower extremities of young adults and has a distinctive histopathologic and molecular profile. It has been rarely described in other locations other than soft tissues, including the gastrointestinal tract. Herein we report a case of clear cell sarcoma of gastrointestinal tract arising in the ileum, which is rich in osteoclast-like giant cells with a review of the literature.

Malignant melanoma of soft parts with osteoclast-rich giant cells: A rare tumour of the jejunum

Malignant melanoma of soft parts (MMSP), first described by Franz M. Enzinger, is a rare tumour of unknown cell origin. We describe a case of a 45-year-old male who presented with a one-year history of abdominal pain, weakness, and anaemia. Computerised tomography enteroclysis showed a mass in the jejunum that was suggestive of a gastrointestinal stromal tumour. An ulceroinfiltrative lesion measuring 6.5 x 4 x 2cm was identified. Microscopy revealed typical features of MMSP with numerous osteoclasts-like giant cells. The diverse histomorphology and immunohistochemical characteristics of this case involving a rare tumour at a rare site is presented.

Clear cell sarcoma of the esophagus: report of a case

We report a rare case of clear cell sarcoma of the esophagus and review the literature regarding clear cell sarcomas of the gastrointestinal tract. A 57-year-old male was admitted with dysphagia during swallowing. Preoperative imaging studies, including upper gastrointestinal endoscopy and endoscopic ultrasonography, showed that the tumor was located between the mucosa and the muscularis propria of the lower esophagus. We performed subtotal esophagectomy with gastric tube reconstruction. Pathological findings of the tumor showed mixed spindle cells and oval cells. Immunohistochemical staining showed that the tumor cells were positive for S-100, vimentin and neuron-specific enolase and negative for α-smooth muscle actin, myoglobin and c-kit. Fluorescence in situ hybridization using a Ewing sarcoma breakpoint region 1 probe showed split signals in a small percentage of cells. We finally diagnosed the patient with clear cell sarcoma of the esophagus.

Clear cell sarcoma-like tumor of the gastrointestinal tract, presenting as a second malignancy after childhood hepatoblastoma

Clear cell sarcoma-like tumor of the gastrointestinal tract (CCSLGT) is a rare malignant neoplasm arising within the wall of the small bowel, stomach, or large bowel, predominantly in children and young adults. It is an aggressive tumor with a high rate of local recurrence, metastases, and early death from disease. Histologically, it is composed of relatively monomorphic ovoid or round cells with clear to eosinophilic cytoplasm, arranged in sheets and sometimes papillary or alveolar architectures, often with CD68-positive osteoclast-like giant cells in variable numbers, and is associated with EWSR1-CREB1 gene fusions. Its pathogenesis is unknown, and histologically it can be easily confused with a variety of intra-abdominal neoplasms. We describe a case of CCSLGT with molecular characterization, presenting as an acutely obstructing small bowel mass in a 33-year-old male, which occurred as a second malignant neoplasm 20 years after treatment with surgery, radiotherapy, and cisplatin and doxorubicin chemotherapy for childhood hepatoblastoma. This gives further insight into the clinical setting of this highly aggressive neoplasm and highlights the use of radiation therapy as a possible etiologic factor.

Malignant gastrointestinal neuroectodermal tumor: clinicopathologic, immunohistochemical, ultrastructural, and molecular analysis of 16 cases with a reappraisal of clear cell sarcoma-like tumors of the gastrointestinal tract

The clinical, histologic, immunophenotypic, ultrastructural, and molecular features of a distinctive gastrointestinal tumor are described. Sixteen patients, 8 women and 8 men aged 17 to 77 years (mean age, 42 y; 63% less than 40 y) presented with abdominal pain, intestinal obstruction, and an abdominal mass. Mean tumor size was 5.2 cm (range, 2.4 to 15.0 cm). The tumors arose in the small bowel (10), stomach (4), and colon (2) and were histologically characterized by a sheet-like or nested population of epithelioid or oval-to-spindle cells with small nucleoli and scattered mitoses. Five cases showed focal clearing of the cytoplasm. Scattered osteoclast-type multinucleated giant cells were present in 8 cases. The tumor cells were positive for S-100 protein, SOX10, and vimentin in 100% of cases, for CD56 in 70%, for synaptophysin in 56%, for NB84 in 50%, for NSE in 45%, and for neurofilament protein in 14% of cases. All cases tested were negative for specific melanocytic, gastrointestinal stromal tumors, epithelial, and myoid markers. Ultrastructural examination of 5 cases showed features of primitive neuroectodermal cells with clear secretory vesicles, dense-core granules, occasional gap junctions, and no evidence of melanogenesis. EWSR1 gene rearrangement was assessed by fluorescence in situ hybridization in 14 cases. Twelve cases (86%) showed split EWSR1 signal consistent with a chromosomal translocation involving EWSR1. One case showed extra intact signals, indicating that the nuclei possessed either extra copies of the EWSR1 gene or chromosome 22 polysomy. Only 1 case showed no involvement of the EWSR1 gene. Six cases demonstrated rearrangement of the partner fusion gene ATF1 (46%), and 3 showed rearrangement of CREB1 (23%); 2 cases lacked rearrangement of either partner gene. Clinical follow-up was available in 12 patients and ranged from 1.5 to 106 months. Six patients died of their tumors (mean survival, 32 mo; 83% less than 24 mo). At last follow-up, 4 patients were alive with regional, lymph node, and liver metastases, and 2 patients were alive with no evidence of disease. The tumor described here is an aggressive form of neuroectodermal tumor that should be separated from other primitive epithelioid and spindle cell tumors of the gastrointestinal tract. The distinctive ultrastructural features and absence of melanocytic differentiation serve to separate them from soft tissue clear cell sarcomas involving the gastrointestinal tract. The designation "malignant gastrointestinal neuroectodermal tumor" is proposed for this tumor type.

Soft tissue tumors of uncertain origin

Many soft tissue tumors of childhood lack obvious differentiation toward a defined mesenchymal tissue type or have a phenotype that does not correspond to any defined normal tissue. These challenging tumors are currently regarded as neoplasms of uncertain differentiation. Nonetheless, there have been great strides in the understanding of their pathologic and genetic features and biologic underpinnings. The application of new genetic information to the pathologic diagnosis among this group of tumors is an emerging area in diagnostic pediatric pathology. This article reviews the clinicopathologic features of tumors of uncertain and/or miscellaneous origin, with an emphasis on the unique aspects of these neoplasms in children and adolescents, use of diagnostic adjuncts, and differential diagnosis.

Selected unusual tumors of the stomach: a review

Several unusual stomach tumors have been recently described. In addition, some tumors that are often encountered in other sites may rarely occur as primary gastric tumors. The diagnostic surgical pathologist needs to be aware of some of these lesions to prevent misdiagnosis. This overview discusses the key clinical features, pathology, immunohistochemistry, and relevant molecular findings of multiple minute gastrointestinal stromal tumors and interstitial cell of Cajal hyperplasia, nerve sheath tumors (schwannoma and perineurioma), gastroblastoma, granular cell tumor, glomus tumor, plexiform angiomyxoid myofibroblastic tumor, and primary clear cell sarcoma of the gastrointestinal tract that occur as primary gastric neoplasms.

Intra-abdominal clear-cell sarcoma: a report of 3 cases, including 1 case with unusual morphological features, and review of the literature

Clear-cell sarcoma (CCS) is a soft-tissue neoplasm that morphologically resembles cutaneous malignant melanoma but has a distinct molecular profile. Gastrointestinal and intra-abdominal CCSs are very rare. Here, the authors present 3 cases of intra-abdominal CCS and review the literature. Of these cases, 2 involved the small bowel, and 1 involved the peritoneum. Cases 1 and 3 had the characteristic CCS morphology, but case 2 was morphologically unusual and therefore difficult to diagnose. It had relatively small cells with less prominence of clear cells; many pseudoglandular structures were also present. It also showed aberrant expression of epithelial membrane antigen (EMA). The other 2 cases also involved some diagnostic uncertainty and were therefore referred to specialized centers. The authors wish to emphasize the importance of molecular studies in making a conclusive diagnosis of intra-abdominal CCS.