Retrospective Analyses of PD-L1, LAG-3, TIM-3, OX40L Expressions and MSI Status in Gastroenteropancreatic Neuroendocrine Neoplasms.

We investigated expressions of PD-L1, LAG-3, TIM-3, and OX40L as immune checkpoint proteins, and MSI (repetitive short-DNA-sequences due to defective DNA-repair system) status were analyzed with immunohistochemistry from tissue blocks. Of 83 patients, PD-L1 expression was observed in 18.1% (n = 15) of the patients. None of the patients exhibited LAG-3 expression. TIM-3 expression was 4.9% (n = 4), OX40L was 22.9% (n = 19), and 8.4% (n = 7) of the patients had MSI tumor. A low-to-intermediate positive correlation was observed between PD-L1 and TIM-3 expressions (rho: 0.333, p < 0.01). Although PD-L1 expression was higher in grade 3 NET/NEC, MSI status was prominent in grade 1/2 NET.

Molecular and immunohistochemical comparison between primary gastrointestinal mucosal melanomas and atypical gastrointestinal stromal tumors.

BACKGROUND: It is sometimes challenging to differentiate between gastrointestinal (GI) mucosal melanoma and gastrointestinal stromal tumors (GISTs) because they share some similarities in histological and molecular features. In this study, we investigated their clinicopathological and molecular features. METHODS: Four primary GI mucosal melanomas and 4 atypical GISTs resected from 2017 to 2019 were included. Electronic medical records and histology slides were reviewed and, if needed, immunohistochemical stainings were additionally done. Somatic mutations were analyzed using whole exome sequencing (WES) with tumors and matched normal tissues. RESULTS: By immunohistochemistry, GISTs were positive for CD117 (4 of 4), DOG1 (4 of 4), and CD34 (2 of 4). In contrast, melanomas were positive for CD117 (2 of 4), HMB-45 (4 of 4), Melan-A (4 of 4), and S100 protein (3 of 4). Using WES, the KIT mutation was detected in 2 of 4 GISTs and 1 of 4 melanomas, all of which showed strong CD117 immunoreactivity. PDGFRA mutation was detected in 2 of 4 GISTs but 0 of 4 melanomas. TP53, NF1, RB1, TERT, and KMT2D mutations were detected in 1 of 4 melanomas but 0 of 4 GISTs. A patient with KIT-mutated melanoma was treated with Gleevec and has remained disease-free for 1 year. CONCLUSIONS: GISTs and GI melanomas have a wide histopathological spectrum. Appropriate ancillary studies can be helpful for proper diagnosis and optimal treatment.

Benefit of Gene Expression Profiling in Gastrointestinal Neuroendocrine Tumors of Unknown Primary Origin.

BACKGROUND/AIM: Cancer of unknown primary (CUP), representing 3-5% of all newly diagnosed cancers in the United States, is a presumptive, non-definitive diagnosis rendered when a primary tumor site cannot be identified after exhaustive diagnostic evaluation, including cases of neuroendocrine neoplasms (NENs). CUPs are characterized by findings that are challenging to reconcile, including inconclusive immunohistochemical (IHC) stains, an undifferentiated morphologic phenotype, history of multiple cancers, a clinical presentation that is discordant from histologic findings, an atypical distribution of metastases, or lack of expected response to treatment. For a significant subset of NENs (10%), traditional diagnostic evaluation is unable to determine a primary tumor site using histomorphology and IHC stains. Gene expression profiling (GEP) of either mRNA or microRNA is the technique utilized in the three commercially available platforms that provide a prediction of tumor type in cases of diagnostic uncertainty of CUPs, including those with neuroendocrine differentiation. Case Series Report: Here we present four cases of NENs, where the diagnosis based upon histomorphological and IHC features presented a unique challenge that ultimately benefited from the integration of molecular tumor classification using the validated assay. CancerTYPE ID by Biotheranostics is based on a quantitative RT-PCR assay that uses a computational algorithm to measure the collective expression of 92 genes (87 cancer-related genes and 5 control genes). This case series reports five appropriate clinical scenarios that highlight the utility of a GEP-based assay to effectively provide a molecular tumor classification to identify NEN subtypes and tumor primary site of origin. CONCLUSION: These cases demonstrated that the CancerTYPE ID test was able to resolve challenging diagnoses for primary and metastatic NENs. These cases emphasize the clinical need of utilizing a GEP-based assay for determining the anatomic site of origin and NEN subtyping, both essential for the appropriate clinical management of NENs.

Some Morphology Frontiers of Dysplasia in the Tubular Gastrointestinal Tract: The Rodger C. Haggitt Memorial Lecture.

This review, based on the content of the 2020 US Gastrointestinal Pathology Society's Rodger Haggitt Lecture, concerns an array of tubular gastrointestinal tract dysplastic or possible "predysplastic lesions" with an almost purely morphologic focus based on our collaborative efforts over the past few years. These processes include esophageal epidermoid metaplasia, Barrett esophagus-associated dysplasia, polypoid gastric dysplastic lesions, small intestinal dysplasia, and the ability of metastases to mimic it, the controversial "serrated epithelial change" encountered in the setting of long-standing ulcerative and Crohn colitis, and recently described anal columnar human papilloma virus-associated neoplasms.

Secondary malignancy after urologic reconstruction procedures: a multi-institutional case series.

Urinary diversion and reconstructive urologic procedures are most often performed by incorporating various intestinal segments into the urinary tract. Although the risk of malignancy, among other complications, is well recognized and occurs most frequently after ureterosigmoidostomies and cystoplasties, data on the histopathologic and immunohistochemical characteristics of these tumors are scant. This study aims to evaluate the clinicopathological features of secondary tumors arising after urologic reconstruction procedures. Eleven cases were identified among five collaborating academic institutions. The average age was 51.7 years, and the M:F ratio was 8:3. Surgical procedures included 7 ileal conduits, 2 gastrocystoplasties, 1 augmentation cystoplasty not otherwise specified (NOS), and 1 Indiana pouch. Median time from reconstruction to malignancy was 36 years. Malignancy included adenocarcinoma in 10 patients (intestinal type in 6, gastric in 2, signet-ring cell in 1, undetermined type after neoadjuvant treatment in 1) and squamous cell carcinoma in 1. By immunohistochemistry, the adenocarcinomas were CK7 (45%), CK20 (89%), CK903 (78%), CDX2 (89%), SATB2 (67%), and beta-catenin (100%) positive. GATA-3 was negative in all cases. Pathologic stage was T1 (30%), T2 (40%), T3 (20%), and T4 (10%). Regional lymph node and distant metastasis were present in 60% and 20%, respectively. Treatment included multimodality therapy in most patients. On follow-up (mean, 27.4 months), 2 patients were dead (1 of disease), 3 were alive with disease, 4 were alive without disease, and 2 were lost to follow-up. Secondary malignancy arising within urologic reconstruction is rare, most frequently has adenocarcinoma morphology, presents late, and behaves aggressively.

Down-regulation of SOCS6: an unfavorable prognostic factor for gastrointestinal stromal tumor proven by survival analysis.

BACKGROUND: Many studies reporting that down-regulation of SOCS6 plays vital roles in promoting progression of malignant tumors have been published. The present study was performed to evaluate whether SOCS6 was significantly associated with prognosis of GIST patients. METHODS: Immunohistochemical staining was accomplished to evaluate the expression levels of SOCS6 among GIST patients. The impacts of SOCS6 expression on overall survival (OS) and recurrence-free survival (RFS) of GIST patients were assessed by Cox proportional hazard regression model analysis and Kaplan-Meier curve analysis. RESULTS: It was demonstrated that the expression level of SOCS6 was significantly associated with tumor size (P=0.001). Then according to Kaplan-Meier curve analysis, low expression of SOCS6 was significantly correlated with worse OS and RFS of GIST patients. Ultimately, it was revealed by Cox proportional regression model analysis that low expression of SOCS6 was an independent predictive factor for OS and RFS. CONCLUSIONS: Low expression of SOCS6 was an independent prognostic factor for GIST, suggesting its potential as a novel biomarker predicting survival of GIST patients.

An algorithmic approach utilizing CK7, TTF1, beta-catenin, CDX2, and SSTR2A can help differentiate between gastrointestinal and pulmonary neuroendocrine carcinomas.

Primary gastrointestinal neuroendocrine carcinoma (GI-NEC) cannot be distinguished morphologically from pulmonary neuroendocrine carcinoma (P-NEC). This can present a significant diagnostic challenge in cases where site of origin cannot be readily determined. To identify immunohistochemical (IHC) markers that can be used to reliably distinguish between GI-NECs and P-NECs, we constructed 3-mm tissue microarrays, one containing 13 GI-NECs and one containing 20 P-NECs. IHC was performed on both microarrays using 21 stains: AE1/AE3, CK7, CK20, synaptophysin, chromogranin, CD56, INSM1, SSTR2A, CDX2, SATB2, TTF1, Napsin A, PR, GATA3, PAX8, ISL1, beta-catenin, AFP, SMAD4, Rb, and p53. For GI-NEC, the most strongly expressed marker was synaptophysin (mean H-score 248), while AE1/AE3 was the most strongly expressed in P-NEC (mean H-score 230), which was stronger than in GI-NEC (p = 0.011). Other markers that were stronger overall in P-NEC than in GI-NEC included CK7 (p < 0.0001) and TTF1 (p < 0.0001). Markers that were stronger overall in GI-NEC than in P-NEC included SSTR2A (p = 0.0021), SATB2 (p = 0.018), CDX2 (p = 0.019), and beta-catenin (nuclear; p = 0.029). SMAD4, Rb, and p53 showed similar rates of abnormal protein expression. Based on these results, a stepwise algorithmic approach utilizing CK7, TTF1, beta-catenin, CDX2, and SSTR2A had a 91% overall accuracy in distinguishing these GI-NEC from P-NEC. This was tested on a second cohort of 10 metastatic GI-NEC and 10 metastatic P-NEC, with an accuracy in this cohort of 85% and an overall accuracy of 89% for the 53 cases tested. Our algorithm reasonably discriminates GI-NEC from P-NEC using currently available IHC stains.

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.

Gastrointestinal mixed adenoneuroendocrine carcinoma (MANEC): An immunohistochemistry study of 13 microsatellite stable cases.

BACKGROUND: Mixed adenoneuroendocrine carcinoma (MANEC) is currently included in the category of neuroendocrine carcinomas but the therapeutically management is not yet defined. AIMS: To present the immunohistochemical (IHC) features of the epithelial mesenchymal transition (EMT) of MANEC. MATERIALS AND METHODS: The clinicopathological features of 13 consecutive cases of MANEC (6 gastric and 7 colorectal) were correlated with the IHC expression of the biomarkers E-cadherin, ß-catenin, N-cadherin, vimentin, maspin, CD44 and S100. In all of the cases open surgery was performed. RESULTS: All of the cases showed microsatellite stable status, expressed E-cadherin and membrane ß-catenin in both components (neuroendocrine and adenocarcinoma) and were negative for N-cadherin, vimentin and S-100. The colorectal MANECs were negative for maspin. In gastric MANECs, maspin showed cytoplasm positivity in the neuroendocrine component and nuclear translocation in the adenocarcinoma cells. CD44 was positive in all of the cases, in both components. No tumor buddings were identified. Three of the 13 patients survived for at least 32 months, all of them showing lymphatic emboli but not lymph node metastases. Pure neuroendocrine lymph node metastases were seen in only four of the cases: one from stomach, two of the ascending colon and two cases of the upper rectum. CONCLUSIONS: Gastrointestinal MANEC is a microsatellite stable tumor with nodular growth, which components might originate from a CD44-positive stem-like precursor cell. Lymph node status remains the most reliable prognostic parameter and agressivity seems to not be influenced by tumor budding degree or EMT-related features. The histologic aspect of metastatic component (neuroendocrine versus adenocarcinoma) should be included in the histopathological reports and might be used for establishing the proper-targeted therapy of MANEC.

SATB2 Is Superior to CDX2 in Distinguishing Signet Ring Cell Carcinoma of the Upper Gastrointestinal Tract and Lower Gastrointestinal Tract.

Signet ring cell carcinomas of the gastrointestinal (GI) tract are clinically aggressive neoplasms with frequent intra-abdominal metastases at initial presentation. Currently available immunohistochemistry (IHC) markers cannot distinguish signet ring cell carcinomas of the lower GI tract and upper GI tract, suggesting the need for more specific diagnostic markers. SATB2 is a novel, sensitive marker for colorectal carcinoma. We hypothesized that SATB2 IHC can reliably identify primary and metastatic signet ring cell carcinomas of lower GI tract origin. SATB2 and CDX2 IHC was performed on 159 primary (n=93) and metastatic (n=66) signet ring cell carcinomas of GI tract origin and 13 metastatic breast carcinomas with signet ring cell features. Positive SATB2 expression (SATB2) was identified in 82% (27/33) of appendiceal, 88% (43/49) of colorectal, 13% (7/54) of gastric, and 35% (8/23) of esophageal/esophagogastric junction signet ring cell carcinomas. Primary and metastatic signet ring cell carcinomas of lower GI tract origin were more frequently SATB2 than those from upper GI tract (70/82, 85% vs. 15/77, 19%, P<0.01). Compared with CDX2, SATB2 and dual-positive staining for SATB2 and CDX2 both had higher specificities for signet ring cell carcinomas from the lower GI tract (81% vs. 49% and 86% vs. 49%, respectively, P<0.01 for both). Two (15%) metastatic breast carcinoma were SATB2, but all 13 demonstrated negative CDX2 staining. In summary, our results show SATB2 is a relatively specific immunohistochemistry marker for both metastatic and primary signet ring cell carcinomas of lower GI tract origin.

Long noncoding RNA HOTAIR is upregulated in an aggressive subgroup of gastrointestinal stromal tumors (GIST) and mediates the establishment of gene-specific DNA methylation patterns.

Aberrant alterations of DNA methylation are common events in oncogenesis. The origin of cancer-associated epigenetic defects is of interest for mechanistic understanding of malignant transformation and-in the long run-therapeutic modulation of DNA methylation in a locus-specific manner. Given the ability of certain long noncoding RNAs to operate as an interface between DNA and the epigenetic modification machinery which can interact with DNA methyltransferases, we hypothesized-considering HOTAIR as an example-that this transcript may contribute to gene specificity of DNA methylation. Using gastrointestinal stromal tumors (GISTs, n = 67) as a model, we confirmed upregulation of HOTAIR in tumors with high risk of recurrence and showed high abundance of the transcript in GIST cell lines. HOTAIR knockdown in GIST-T1 cells triggered transcriptional response of genes involved in the organization and disassembly of the extracellular matrix and, notably, induced global locus-specific alterations of DNA methylation patterns. Hypomethylation was induced at a total of 507 CpG sites, whereas 382 CpG dinucleotides underwent gain of methylation upon HOTAIR depletion. Importantly, orchestrated gain or loss of methylation at multiple individual CpG sites was shown for cancer-related DPP4, RASSF1, ALDH1A3, and other targets. Collectively, our data indicate that HOTAIR enables target specificity of DNA methylation in GIST and is capable of dual (hypo- and hypermethylation) regulation by a yet to be defined mechanism. The results further suggest the feasibility of manipulating DNA methylation in a targeted manner and are of interest in the context of epigenetic cancer therapy.

Cytological Findings of Gastrointestinal Stromal Tumor-Derived Bone Metastasis.

OBJECTIVE: Procedures for diagnosing bone tumors should be rapid and minimally invasive. Thus, cytological examinations are more useful for such purposes than histological examinations. In order to identify cytomorphological findings that could be used to diagnose bone metastasis from gastrointestinal stromal tumors (GIST), previous cases were reviewed. STUDY DESIGN: Cytological samples of 7 lesions from 4 patients with GIST-derived bone metastasis, which were obtained from 2001 to 2017 at the JFCR Cancer Institute Hospital, were reviewed. RESULTS: The metastasis of GIST to the bone was clinically suspected before the cytological and histological examinations in all cases since they all involved other metastatic lesion(s), and characteristic osteolytic lesions were detected on radiological images. Although various cell shapes were encountered, spindle cell proliferation was seen in all cytological samples. No pleomorphism was apparent. Characteristic nuclear findings were observed. All of the cases could be diagnosed as GIST-derived bone metastasis. CONCLUSION: GIST-derived bone metastasis can be diagnosed by examining cytological samples.

[Gastrointestinal leiomyoma with interstitial cells of Cajal: mimicker of gastrointestinal stromal tumor].

Objective: To study clinical and pathologic characteristics of leiomyomas of the gastrointestinal tract, and to investigate the distribution characteristics of interstitial cells of Cajal ( ICCs ) in gastrointestinal leiomyomas. Methods: One hundred and forty-seven cases of leiomyomas of gastrointestinal tract were collected at the Second Affiliated Hospital of Zhengzhou University from June 2012 to June 2017. Clinical and pathologic findings were analyzed, combined with immunohistochemistry, Alcian blue-osafranin staining and molecular study. Results: The age of patients ranged from 13-82 years with mean age of 52 years. Male to female ratio was about 1∶2. Histologically, all tumors were composed of ovoid to spindle cells arranged in short intersecting fascicles. All tumors were diffusely and strongly positive for smooth muscle antibodies, desmin and h-caldesmon by immunohistochemical staining. A prominent interspersed subpopulation of elongated/dendritic-like cells with CD117 and DOG1 positivity (accounting for 1% to 30% of all tumor cells) and negative for Alcian blue-osafranin staining was identified in all esophageal leiomyomas, 16 of 20 (80%) gastric leiomyomas and 3 of 12 small bowel leiomyomas, but none in colonic/rectal leiomyomas. Mutational analysis in 16 cases showed absence of mutation in exons 9, 11, 13 or 17 of C-KIT and exons 12 or 18 of PDGFRA. Conclusions: ICCs are identified in esophageal and gastric leiomyomas, as well as in small percentage of intestinal leiomyomas. Such findings may bring significant diagnostic pitfalls for misdiagnosis as gastrointestinal stromal tumor. Careful attention to the distribution of CD117 and DOG1 positive cells and molecular mutation analysis of C-KIT and PDGFRA may be necessary to establish the correct diagnosis.

Association of Dasatinib With Progression-Free Survival Among Patients With Advanced Gastrointestinal Stromal Tumors Resistant to Imatinib.

Importance: Gastrointestinal stromal tumors (GISTs) are life-threatening when metastatic or not amenable to surgical removal. In a few patients with advanced GISTs refractory to imatinib mesylate, treatment with sunitinib malate followed by regorafenib provides tumor control; however, additional active treatments are needed for most patients. Objective: To evaluate the 6-month progression-free survival (PFS), tumor objective response, and overall survival rates in patients with GISTs treated with dasatinib. Design, Setting, and Participants: This single-arm clinical trial used a Bayesian design to enroll patients 13 years or older with measurable imatinib-refractory metastatic GISTs treated at 14 sarcoma referral centers from June 1, 2008, through December 31, 2009. A control group was not included. Patients were followed up for survival for a minimum of 5 years from date of enrollment. Tumor imaging using computed tomography or magnetic resonance imaging was performed every 8 weeks for the first 24 weeks and every 12 weeks thereafter. Tumor response was assessed by local site using the Choi criteria. Treatment was continued until tumor progression, unacceptable toxic effects after reduction in drug dose, or patient or physician decision. Archival tumor tissue was evaluated for expression of the proto-oncogene tyrosine-protein kinase Src (SRC), phosphorylated SRC (pSRC), and succinate dehydrogenase complex iron sulfur subunit B (SDHB) proteins and for mutation in the V-Kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog (KIT) and platelet-derived growth factor receptor α (PDGFRA) genes. Data analysis was performed from May 19, 2017, through December 20, 2017. Interventions: Dasatinib, 70 mg orally twice daily. Main Outcomes and Measures: The primary end point was the 6-month PFS estimate using greater than 30% as evidence of an active drug and less than 10% as evidence of inactive treatment. Results: In this study, 50 patients were enrolled (median age, 60 years; age range, 19-78 years; 31 [62%] male and 19 [38%] female; 41 [82%] white), and 48 were evaluable for response. The estimated 6-month PFS rate was 29% in the overall population and 50% in a subset of 14 patients with pSRC in GISTs. Objective tumor response was observed in 25%, including 1 patient with an imatinib-resistant mutation in PDGFRA exon 18. Conclusions and Relevance: Dasatinib may have activity in a subset of patients with imatinib-resistant GISTs. Further study is needed to determine whether pSRC is a prognostic biomarker.

[Clinicopathologic and molecular characteristics of malignant gastrointestinal neuroectodermal tumors].

Objective: To investigate the clinicopathologic and molecular characteristics, diagnostic, differential diagnostic and prognostic features of malignant gastrointestinal neuroectodermal tumor. Methods: Two cases of malignant gastrointestinal neuroectodermal tumor were retrieved; the clinical and radiologic features, histomorphology, immunophenotype, molecular genetics and prognosis were analyzed and the relevant literature reviewed. Results: Case 1 was a 57-year-old male, presented with recurrent abdominal pain and melena. Pelvic imaging showed a circumscribed thickening of the wall of a small intestinal segment, and a malignant lymphoma was favored. Case 2 was a 24-year-old male, presented with recurrent small intestinal malignancy. Imaging demonstrated multiple masses in the peritoneal and pelvic cavities, and a malignant gastrointestinal stromal tumor with multiple metastases was suspected. Grossly both tumors were located mainly in the muscularis propria of small intestine. Case 1 showed a single 5.5 cm tumor; and case 2 consisted of two tumors measuring 4 cm and 6 cm respectively. Microscopic examination of both tumors showed small round blue, but focally spindled or clear tumor cells in solid pattern. The tumor cells had scanty cytoplasm, indistinctive nucleoli and brisk mitoses. Osteoclast-like giant cells were dispersed within the stroma. In case 1 rosette-like and pseudo-papillary growth patterns were noted, and in case 2 there were variable-sized hemorrhagic cysts. By immunohistochemistry, both tumors showed strong and diffuse expression of SOX10 and S-100, and focal to diffuse expression of neuroendocrine markers (CD56 or synaptophysin). Case 2 exhibited focal reactivity to pan-cytokeratin. Both tumors lacked expression of markers associated with gastrointestinal stromal tumor, smooth muscle tumor, melanoma (HMB45 or Melan A), dendritic cell tumor and Ewing sarcoma. Fluorescence in situ hybridization analysis demonstrated EWSR1 rearrangement in both tumors and the next generation sequencing confirmed EWSR1-ATF1 gene fusion in case 2. At follow-up of 16 months, case 1 was recurrence or metastasis free; whereas case 2 showed multiple recurrences and metastases within 19 months although stable disease was transiently achieved when treated with combinations of multidrug and targeted chemotherapy. Conclusions: Malignant gastrointestinal neuroectodermal tumor is a rare and aggressive soft tissue sarcoma with a predilection for small intestine. It has distinctive morphologic, immunohistochemical and molecular characteristics and needs to be distinguished from other small blue round and spindle cell tumors that occur in the gut. Careful attentions to its characteristic histomorphology with the judicious use of immunohistochemistry and molecular genetics can help to distinguish this tumor from its many mimickers.

Thymosin beta-4 overexpression correlates with high-risk groups in gastric gastrointestinal stromal tumors: A retrospective analysis by immunohistochemistry.

BACKGROUND: Thymosin beta-4 (Tß4) is a protein that is linked to a number of important biological actions and recently tumor progression and poor prognosis of some tumors. The aim of this study was to evaluate Tß4 expression in gastric GISTs and correlate with some clinicopathological characteristics related with prognosis and clinical outcome in order to add further data to the current literature. METHODS: Tß4 antibody was applied to the 4µm-thick paraffin sections of 57 gastric GISTs by immunohistochemistry. RESULTS: Tß4 expression was found to be directly corrrelated with higher risk groups, tumor size, mitotic count, cellularity, and necrosis while it was inversely correlated with overall survival (OS) by univariate analysis (p=0.000, p=0.001, p=0.000, p=0.025, p=0.023, and p=0.042, respectively). The direct association between Tß4 expression and risk groups were also supported by multivariate analysis (p=0.000, ß=0.497, t=4.374). CONCLUSION: Overexpression of Tß4 was found to be related with predictive characteristics for tumor progression and adverse prognosis. Thus, we suggest that overexpression of Tß4 might play a role in the progression of gastric GISTs and might be used as a potential prognostic tool as well as a target for novel therapies.

Surgical Pathology of Gastrointestinal Stromal Tumors: Practical Implications of Morphologic and Molecular Heterogeneity for Precision Medicine.

Gastrointestinal stromal tumor (GIST), the most common mesenchymal neoplasm of the gastrointestinal tract, exhibits diverse histologic and clinical manifestations. With its putative origin in the gastrointestinal pacemaker cell of Cajal, GIST can arise in association with any portion of the tubular gastrointestinal tract. Morphologically, GISTs are classified as spindled or epithelioid, though each of these subtypes encompasses a broad spectrum of microscopic appearances, many of which mimic other histologic entities. Despite this morphologic ambiguity, the diagnosis of GIST is aided in many cases by immunohistochemical detection of KIT (CD117) or DOG1 expression. The natural history of GIST ranges from that of a tumor cured by surgical resection to that of a locally advanced or even widely metastatic, and ultimately fatal, disease. This clinicopathologic heterogeneity is paralleled by an underlying molecular diversity: the majority of GISTs are associated with spontaneous activating mutations in KIT, PDGFRA, or BRAF, while additional subsets are driven by genetic lesions-often inherited-of NF1 or components of the succinate dehydrogenase enzymatic complex. Specific gene mutations correlate with particular anatomic or morphologic characteristics and, in turn, with distinct clinical behaviors. Therefore, prognostication and treatment are increasingly dictated not only by morphologic clues, but also by accompanying molecular genetic features. In this review, we provide a comprehensive description of the heterogenous molecular underpinnings of GIST, including implications for the practicing pathologist with regard to morphologic identification, immunohistochemical diagnosis, and clinical management.

EZH2 overexpression in primary gastrointestinal diffuse large B-cell lymphoma and its association with the clinicopathological features.

Gastrointestinal diffuse large B-cell lymphoma (GI DLBCL) is the most common gastrointestinal lymphoma. Enhancer of zeste homolog 2 (EZH2) has been implicated in the pathogenesis of several cancers. However, EZH2 has not been studied in GI DLBCL. Thus, we investigated EZH2 expression and EZH2 Y641 mutation in 100 GI DLBCL specimens by immunohistochemistry and sequencing. In addition, trimethylated H3K27 (H3K27me3), BCL2, c-MYC, and Ki-67 expression and Helicobacter pylori infection were detected, and BCL2 and c-MYC gene translocation was assessed. EZH2 was overexpressed in 50% of cases. EZH2 overexpression was significantly associated with higher stage (P = .014), higher International Prognostic Index score (P = .003), reduced overall survival rate (P = .030), and H3K27me3 (P = .001) and c-MYC expression (P = .008). We detected EZH2 mutations in 1 of 33 (3.0%) DLBCLs with a germinal center immunophenotype. The frequency of EZH2 Y641 mutation in GI DLBCL was significantly lower than that in patients with DLBCL without gastrointestinal features (P = .022). BCL2 and c-MYC translocation was detected in 6.5% and 5.1% of cases, respectively. BCL2 translocation was detected exclusively in the germinal center B-cell-like subtype. Chronic gastroenteritis was present in all cases, and 36.4% of gastric DLBCL cases had H pylori infection. The data indicate that primary GI DLBCL is closely related with chronic inflammation and has a low frequency of molecular abnormality, and EZH2 overexpression is significantly associated with inferior outcome in patients with primary GI DLBCL; evaluating EZH2 expression has therapeutic implications.

[Advances of circulating biomarkers in gastroenteropancreatic neuroendocrine neoplasms].

Gastroenteropancreatic neuroendocrine neoplam (GEP-NEN) is a rare group of tumors with its incidence rising significantly in recent decades. Because of the late presentation of the disease and limitations in conventional biomarkers, about 50% of GEP-NEN patients manifests advanced disease when diagnosed. Therefore, it is vital to identify circulating biomarkers which can not only be used for early diagnosis but also accurately evaluating the biological behavior of GEP-NEN. This review summarizes the advances of circulating biomarkers in diagnosing and evaluating efficacy of treatment in GEP-NEN. Well-known circulating biomarkers include chromogranin A (CgA), pancreastatin (PST), chromogranin B (CgB), neuron-specific enolase (NSE) and pancreatic peptide(PP). Novel biomarkers including circulating tumor cell(CTC), microRNA and NETest are promising biomarkers with potential clinical benefit, but further researches are needed before their clinical applications.

Human epididymis protein 4 immunostaining of malignant ascites differentiates cancer of Müllerian origin from gastrointestinal cancer.

BACKGROUND: An accurate diagnosis of cancer of Müllerian origin is required before the initiation of treatment. An overlap in clinical presentation and cytological, histological, or imaging studies with other nongynecological tumors does occur. Therefore, immunocytochemistry markers are used to determine tumor origin. Human epididymis protein 4 (HE4) is overexpressed in tissue of epithelial ovarian cancer (EOC). It has shown to be a sensitive and specific serum marker for EOC and to be of value for the differentiation between EOC and ovarian metastases of gastrointestinal origin. The objective of the current study was to evaluate HE4 immunocytochemistry in malignant ascites for differentiation between cancer of Müllerian origin, including EOC, and adenocarcinomas of the gastrointestinal tract. METHODS: Cytological specimens of 115 different adenocarcinomas (45 EOCs, 46 cases of gastric cancer, and 24 cases of colorectal cancer) were stained for HE4, paired box 8 (PAX8), and other specific markers. RESULTS: 91% of the ascites samples from patients with EOC stained for both HE4 and PAX8. The 4 samples without HE4 staining were a clear cell carcinoma, a low-grade serous adenocarcinoma, an undifferentiated adenocarcinoma, and a neuroendocrine carcinoma. All high-grade serous adenocarcinomas (n = 37, 100%) stained with HE4, compared with 94% that stained positively for PAX8. In cases of gastric or colorectal cancer, 25% and 21% of cases, respectively, stained positive for HE4. No PAX8 staining was observed in colorectal or gastric adenocarcinomas. CONCLUSIONS: HE4 staining in ascites is feasible and appears to have a high sensitivity for high-grade serous ovarian cancer. HE4 is a useful addition to the current panel of immunocytochemistry markers for the diagnosis of EOC and for differentiation with gastrointestinal adenocarcinomas. Cancer Cytopathol 2017;125:197-204. © 2016 American Cancer Society.