Gastrointestinal stromal tumors presenting as omental masses--a clinicopathologic analysis of 95 cases. Am J Surg Pathol. 2009;33:1267-1275. [PMID: 19440146 DOI: 10.1097/pas.0b013e3181a13e99]

Primary EGIST of the greater omentum - a rare presentation

Extragastrointestinal stromal tumors (EGISTs) are rare mesenchymal neoplasms, which develop in the retroperitoneum, mesentery, and omentum, lacking continuity to the stomach or intestines. Authors hereby present a female patient with a large heterogeneous abdominal mass as a case of an omental EGIST. A 46-year-old woman was referred to our hospital due to an insidious enlargement and colicky pain in the right iliac fossa. Abdominal palpation revealed a voluminous, freely mobile, and non-pulsatile mesoabdominal bulge expanding to the hypogastrium. On exploratory midline laparotomy, the tumor was densely fused to the greater omentum, not connected to the stomach, without gross involvement of adjacent structures. The large mass was completely excised after adequate mobilization. Immunohistochemical techniques showed strong and diffuse expression of WT1, actin and DOG-1, as well as multifocal c-KIT marking. Mutational study concluded a double mutation of KIT exon 9 and a mutation of PDGFRA exon 18. The patient was submitted to adjuvant treatment with imatinib mesylate 800 mg/day. Despite an extremely diverse presentation, omental EGISTs often remain clinically silent for a long time having enough space to grow before becoming symptomatic. These tumors have a consistent pattern of metastasis that typically spares lymph nodes unlike epithelial gut neoplasms. Surgery remains the preferred treatment for non-metastatic EGISTs of the greater omentum. It is possible that DOG-1 will supplant KIT as the leading marker in the future. The scarcity of knowledge on omental EGISTs implies a close monitoring of these patients to detect local relapse or distant metastasis.

Dataset for reporting of gastrointestinal stromal tumours: recommendations from the International Collaboration on Cancer Reporting (ICCR)

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal tumours of the gastrointestinal tract and are among the most frequent sarcomas. Accurate diagnosis, classification, and reporting are critical for prognostication and patient management, including selection of appropriate targeted therapy. Here we report on international consensus-based datasets for the pathology reporting of biopsy and resection specimens of GIST. The datasets were produced under the auspices of the International Collaboration on Cancer Reporting (ICCR), a global alliance of major international pathology and cancer organizations. An international expert panel consisting of pathologists, a surgical oncologist, and a medical oncologist produced a set of core and noncore data items for biopsy and resection specimens based on a critical review and discussion of current evidence. All professionals involved were subspecialized soft tissue tumour experts and affiliated with tertiary referral centres. Commentary was provided for each data item to explain its clinical relevance and the rationale for selection as a core or noncore element. Following international public consultation, the datasets, which include synoptic reporting guides, were finalized and ratified, and published on the ICCR website. These first international datasets for GIST are intended to promote high-quality, standardised pathology reporting. Their widespread adoption will improve consistency of reporting, facilitate multidisciplinary communication, and enhance comparability of data, all of which will ultimately help to improve the management of patients with GIST. All the ICCR datasets, including these on GIST, are freely available worldwide on the ICCR website (www.iccr-cancer.org/datasets).

Gastrointestinal stromal tumor in the fourth portion of the duodenum does not express the CD117: A case report

Introduction

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the digestive tract.

Presentation of case

54-year-old woman with a history of phyllodes tumor of the left breast he patient was admitted to our hospital for management of retroperitoneal soft tissue tumor, attached to the fourth portion of the duodenum, opposite the head of the pancreas. The patient underwent a large excision of the tumor, the duodenojejunal flexure, and the third and fourth portions of the duodenum along with the head of the pancreas. The histopathological examination confirmed the presence of a spindlecell mesenchymal proliferation. These cells do not express CD117, but they express DOG1. A PDGFRA mutation was identified later. The final diagnosis was duodenal GIST.

Discussion

few cases of GIST in the fourth portion of the duodenum had been reported in the literature. PDGFRA mutation is identified as GISTs tumorigenesis to 15% of cases, and the diagnosis of GISTs is not based solely on the expression of the protein Kit.

Conclusion

the molecular biology examinations are very helpful in the direction of the correct diagnosis in case of negative staining for CD117.

Gastrointestinal Stromal Tumors (GISTs) as Incidental Findings in Gynecological Surgery

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors of the gastrointestinal tract that may be diagnosed incidentally as a part of intra-abdominal surgery for other diseases. This is a single center review to document the incidental finding of GIST at surgery for gynecological malignancies during a 10-yr period. Sixteen cases of incidental GISTs were identified in women ranging in age from 39 to 82 yr. GISTs presented as incidental secondary lesions in women undergoing surgery for other indications, typically primary debulking surgery for tubo-ovarian high-grade serous carcinoma. The GIST was located in the stomach wall in 9 cases. Other sites were cecum, omentum, and mesentery. Diagnosis of GIST was supported by immunohistochemistry in all cases and by molecular studies in 3 cases. Seventy-five percent of cases were micro-GISTs, measuring <2 cm in diameter and, where Miettinen and Lasota criteria could be applied, fitted into "no risk," "very low risk" or "low risk" prognostic groups. Seventy-five percent of women for whom survival data was available, showed disease-free survival at follow-up. The 2 women who died had concurrent high stage or high-grade gynecological malignancy at initial diagnosis.

Clinical Features of Extragastrointestinal Stromal Tumor Compared with Gastrointestinal Stromal Tumor: A Retrospective, Multicenter, Real-World Study

Objective

This study aimed to compare the tumor characteristics and long-term outcomes between EGIST and GIST. The confounding function was applied to improve the result credibility in the case of small sample size. Design, Setting, and Participants. This cohort study enrolled 55 patients with EGIST who underwent surgery and were selected from four high-volume hospitals in China and 221 GIST patients who were collected from one of the four hospitals between January 2006 and September 2017. We used propensity score matching (PSM) and subgroup analysis to compare EGIST with GIST in terms of prognosis. The confounding function was used for sensitivity analysis to reduce unmeasured confounding.

Results

We matched 43 patients in each of the GIST and EGIST groups by PSM. We compared EGIST data with GIST data to explore the prognostic factors between them. In the multivariate Cox regression model, tumor location of EGIST was negatively correlated with overall survival (after PSM: HR, 4.32; 95% CI, 1.22–15.26) or disease-free survival (after PSM: HR, 9.79; 95% CI, 2.22–43.31), which was also intuitively shown in the Kaplan–Meier survival curves (all P values < 0.05). In the subgroup analysis, EGIST with high risk factors had a worse prognosis than GIST. In unmeasured confounding analysis, the overall curve tends to show all combinations of c(0) of c(1) up to 2.0, none of which would bring the corrected relative risk to 1 for OS and DFS. Conclusions and Relevance. EGIST was associated with worse prognosis compared with GIST patients, particularly in EGIST patients with high risk factors, while there was a similar prognosis without those high risk factors.

Current surgical management of duodenal gastrointestinal stromal tumors

Duodenal gastrointestinal stromal tumors (D-GISTs) are uncommon mesenchymal tumors and are managed differently to common duodenal epithelial tumors. They may pose surgical challenges due to their unique but complex pancreaticoduodenal location of the gastrointestinal tract near the ampulla of Vater, pancreas, mesenteric blood vessels, biliary and pancreatic ducts. The surgical management of D-GISTs can be performed safely with good oncological outcomes provided an adequate resection margin can be achieved. The current surgical options of resectable primary D-GISTs varies with increasing complexity depending on the location, size and involvement of surrounding structures such as wedge resection with primary closure, segmental resection with small bowel anastomosis or radical pancreaticoduodenectomy. Laparoscopic approaches have been shown to be feasible and safe with good oncological outcomes in experienced hands. The minimally invasive techniques including robotic-assisted approach will likely increase in the future. D-GISTs have a prognosis comparable to gastric and other small bowel GISTs. However, the heterogeneity of different studies and the limited use of systemic tyrosine kinase inhibitor in the neoadjuvant and adjuvant settings may influence the overall survival of resected D-GISTs. The use of limited resection when condition allows is recommended due to lower surgical morbidity, less postoperative complications and better oncologic outcomes.

A Retrospective Study of Postoperative Outcomes in 98 Patients Diagnosed with Gastrointestinal Stromal Tumor (GIST) of the Upper, Middle, and Lower Gastrointestinal Tract Between 2009 and 2019 at a Single Center in Poland

BACKGROUND Gastrointestinal stromal tumors (GISTs) arise in the smooth muscle pacemaker interstitial cells of Cajal, or similar cells. The aim of this retrospective study between 2009 and 2019 from a single center in Poland was to assess the selected prognostic factors (location, tumor size, mitotic index, body mass index (BMI), length of hospital stay, age, sex, and coexistent neoplasm) and to investigate postoperative outcomes in 98 patients with GIST of the upper, middle, and lower gastrointestinal tract. MATERIAL AND METHODS Between 2009 and 2019, 98 patients (50 women and 48 men) with an average age of 63.8 years (range from 38 to 90 years) were operated on for GIST in the Department of Gastrointestinal Surgery in Katowice, Poland. Based on the intraoperative and postoperative investigations, the tumor size and mitotic index were determined in each case. RESULTS A statistically significant correlation between age and mitotic index (MI) was found (p=0.02). The higher the MI, the younger the age of the patients. However, regardless of sex, younger patients had a tendency to survive longer. A >60-year-old male patient's probability of survival was around 65% after 40 months. Higher mitotic index was also associated with larger tumor size (p<0.0001). Female patients had a tendency to survive longer than males. CONCLUSIONS The findings from this small retrospective study support the importance of preoperative evaluation and frequent postoperative follow-up for patients with GIST of the gastrointestinal tract, particularly in older male patients, and patients with malignant comorbidities, which are associated with increased mortality.

Plexiform fibromyxoma: Case report and literature review

Plexiform fibromyxoma (PF) is a rare mesenchymal neoplasm which can be misdiagnosed as the gastrointestinal stromal tumor. This tumor almost formed a lobulated intramural/submucosal mass in the gastric antrum and prepyloric area. It was considered as a benign tumor that exhibited no recurrence, metastasis, or tumor-related mortality. In this study, we reported 2 cases of gastric PF. The first case was a PF patient coexisting with gastric adenocarcinoma. The second case occurred in the gastric upper body close to gastric fundus. They underwent distal gastrectomy and laparoscopic partial gastric resection, respectively. Both of them exhibited a plexiform growth pattern in the submucosa, muscularis propria, and subserosal adipose tissues. The nodules were composed of abundant myxoid or fibromyxoid matrix riching in small thin-walled blood vessels and bland-looking spindle cells. The first case partially showed staggered growth pattern of PF and adenocarcinoma. Immunohistochemically, the spindle cells were diffusely immunoreactive for SMA and vimentin, and focally immunoreactive for CD10. It was important to distinguish the PF from other spindle cell tumors involving the stomach.

Unusual presentation of small bowel GIST: diffuse omental & mesenteric sarcomatosis

Gastrointestinal stromal tumors (GISTs) represent ~1% of gastrointestinal (GI) tract neoplasms. Unusual presentation of a small bowel GIST with diffuse omental and mesenteric implants in a symptomatic patient is reported. CT scan in a 68-years-old woman showed multiple processes with solid density and colliquation areas in the abdominal cavity. At surgery, an uncommon finding of multiple omental and mesenteric secondary implants was evident. The index mass with 40 cm of adjacent small bowel, omentum and all peritoneal lesions were completely removed. Definitive pathology report showed a small bowel GIST with focal areas of necrosis and high mitotic activity (35 mitosis/50 High Power Fields), with multiple metastases on mesentery and omentum. Patient was therefore submitted to adjuvant treatment with Imatinib and a close follow-up program. Small bowel GIST with high mitotic activity may present with diffuse omental and mesenteric peritoneal seedings. Complete surgical clearance remains the mainstay of treatment.

Extra-Gastrointestinal Stromal Tumor of Prostate

Background:

Extra-gastrointestinal stromal tumor is defined as a mesenchymal neoplasm arising from soft tissues outside the gastrointestinal tract. Prostatic extra-gastrointestinal stromal tumor has rarely been noted.

Case Report:

A 56 year-old man presented with pain in the anal region. A digital rectal examination revealed that the prostate was markedly enlarged with a smooth, bulging surface. Computerized tomography images showed a 6 cm heterogeneous, infiltrative tumor within the prostate gland extending to the trigon of the bladder, left seminal vesicle and rectum. The tru-cut biopsy of the prostate was reported as leiomyoma. It was decided to perform surgery and the masses were easily and completely removed from the adjacent structures. The case was reported as extra-gastrointestinal stromal tumor within the intermediate- risk category with free surgical margins. Four years after the surgery, a locoregional failure was observed and treated with imatinib.

Conclusion:

Stromal tumor, although rare, should be considered in the differential diagnosis in patients with an enlarged prostate.

Mucinous Carcinomatosis: A Rare Association between an Ovarian Tumor and an E-GIST

Pseudomyxoma peritonei (PMP) and extragastrointestinal stromal tumors (E-GISTs) are both rare entities. Most of the time, PMP is associated with an appendiceal tumor. An ovarian mucinous tumor can mimic appendiceal metastases. E-GIST is a mesenchymal tumor that can arise from the omentum, retroperitoneum, mesentery, or pleura. We present a case of an 87-year-old woman with mucinous carcinomatosis and acute intestinal occlusion submitted to an emergency laparotomy. She has found to have a borderline mucinous tumor of the ovary from the intestinal type with several lesions of pseudomyxoma peritonei and an E-GIST from the epiploons retrocavity (intermediated risk). In the literature, no relation was found between these two rare tumors. E-GIST was an incidental finding in the context of a mucinous carcinomatosis.

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.

What is New in Gastrointestinal Stromal Tumor?

The classification "gastrointestinal stromal tumor" (GIST) became commonplace in the 1990s and since that time various advances have characterized the GIST lineage of origin, tyrosine kinase mutations, and mechanisms of response and resistance to targeted therapies. In addition to tyrosine kinase mutations and their constitutive activation of downstream signaling pathways, GISTs acquire a sequence of chromosomal aberrations. These include deletions of chromosomes 14q, 22q, 1p, and 15q, which harbor putative tumor suppressor genes required for stepwise progression from microscopic, preclinical forms of GIST (microGIST) to clinically relevant tumors with malignant potential. Recent advances extend our understanding of GIST biology beyond that of the oncogenic KIT/PDGFRA tyrosine kinases and beyond mechanisms of KIT/PDGFRA-inhibitor treatment response and resistance. These advances have characterized ETV1 as an essential interstitial cell of Cajal-GIST transcription factor in oncogenic KIT signaling pathways, and have characterized the biologically distinct subgroup of succinate dehydrogenase deficient GIST, which are particularly common in young adults. Also, recent discoveries of MAX and dystrophin genomic inactivation have expanded our understanding of GIST development and progression, showing that MAX inactivation is an early event fostering cell cycle activity, whereas dystrophin inactivation promotes invasion and metastasis.

Clinical and pathological characteristics of gastrointestinal stromal tumor (GIST) metastatic to bone

Our aim in this study was to describe the clinical, morphological, and molecular profile of gastrointestinal stromal tumor (GIST) metastatic to bone. We analyzed the morphological, phenotypic, and molecular characteristics of seven cases, and in addition reviewed 17 cases from literature. Sequence analysis of KIT and PDGFRA genes was possible for six cases. For the GIST cases with bone metastasis, the most common primaries were small intestine (29%), stomach (25%), and rectum (21%). Sites of bone metastases were vertebrae (11), pelvis (8), femur (8), ribs (6), humerus (5), skull (3), scapula (1), and mandible (1). The size ranged from 1.5 to 13 cm (median, 3.8 cm). Bone metastases without involvement of any other organ were seen in 17% of the cases and were solitary in 14 (58%). Adjacent soft tissue involvement was present in nearly half of the patients. Bone metastasis was either manifest at the time of diagnosis (28%) or occurred after a mean period of 4.7 years (3 months-20 years). Morphologically, neoplastic cells were spindle in 67%, epithelioid in 13%, and mixed epithelioid and spindle in 20%. CD117, DOG1, and CD34 were positive in 88, 86, and 85% of the cases, respectively. KIT Exon 11 mutations were the most frequent gene alteration (78%), followed by KIT Exon 13 mutations. Of 17 of the cases with available follow-up information, 7 (41%) patients developed bone metastasis under imatinib therapy. Five patients (29%) died of disease within a mean of 17 months. Bone metastases from GIST are usually found in patients with advanced disease and typically present as lytic masses with occasional soft tissue involvement. We could not identify any KIT or PDGFRA alterations predisposing to bone metastasis.

Primary Small Bowel GIST Presenting as a Life-Threatening Emergency: A Report of Two Cases

Gastrointestinal stromal tumor (GIST) is a rare stromal neoplasm, which represents the most common mesenchymal tumor of the gastrointestinal tract. It is characterized by indolent clinical symptoms, although it can present as a life-threatening emergency. Herein, we present two cases of primary small bowel GIST treated at our department. A 68-year-old female patient presented to our emergency department with a diffuse abdominal pain of acute onset. Imaging studies revealed a mass at proximal jejunum, with a nearby free air and fluid. At surgery, a mass of 9 cm was found at proximal jejunum, 3 cm distal to the treitz ligament, with perforation on the lateral wall of the mass. En bloc resection was performed. Pathology report was positive for gastrointestinal stromal tumor. A 70-year-old male patient presented to our emergency department with 3 days of dark tarry stool and few hours of hematochezia. Computed tomography angiography revealed a mass at the pelvis, with calcifications, attached to the distal ileum, with intraluminal blush of intravenous iodine. At surgery, a mass of 8 cm at the distal ileum was found. Resection of the mass along with a 20 cm of ileum was completed. Histopathology report was positive for malignant gastrointestinal stromal tumor.

Cytohistological and immunohistochemical characteristics of spindle-shaped mesenchymal neoplasms occurring in the gastrointestinal tract

The purpose of the present review is to analyze the cytohistological and immunohistochemical characteristics of spindle-shaped mesenchymal gastrointestinal neoplams (MGNs), a group of unusual neoplastic conditions with different biological behavior. These tumors exhibit clinical pictures strictly related to the site of origin and dimensions, even if they appear generally with an intramural localization. This latter point may suggest an useful application of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA), mainly followed by the cell-block procedure (CBP) in the differential diagnostic approach. First of all, we discuss the most common entity of MGNs represented by gastrointestinal stromal tumors (GISTs), analyzing the morphologic characteristics and stressing the strength of immunohistochemical algorithm for diagnostic purposes. Successively, we have reported the less common group of spindle-shaped MGNs comprehensive of those arising elsewhere the soft tissues, such as leiomyomas, leiomyosarcomas, schwannomas, inflammatory myofibroblastic tumor and intra-abdominal desmoid fibromatosis. Finally, very uncommon spindle-shaped MGNs, like clear cell, follicular dendritic cell, undifferentiated pleomorphic and radiation-induced sarcomas as well as spindle cell dedifferentiated liposarcomas, have been briefly mentioned.

Clinicopathological features and prognosis of omental gastrointestinal stromal tumor: evaluation of a pooled case series

Clinicopathological features and prognosis of omental GISTs are limited due to the extremely rare incidence. Therefore, the aim of the present study was to investigate the clinicopathological features and prognosis of omental GISTs. Omental GISTs cases were obtained from our center and from case reports and clinical studies extracted from MEDLINE. Clinicopathological features and survivals were analyzed. A total of 99 cases of omental GISTs were enrolled in the present study. Omental GISTs occurred predominantly in greater omentum (78/99, 78.8%). The majority of tumors exceeded 10 cm in diameter (67/98, 68.3%) and were high risk (88/96, 91.7%). Histological type was correlated with tumor location and mutational status. The five year DFS and DSS was 86.3% and 80.6%, respectively. Mitotic index was risk factor for prognosis of omental GISTs. Prognosis of omental GISTs was worse than that of gastric GISTs by Kaplan-Meier analysis. However, multivariate analysis showed that the prognosis was comparable between the two groups. The majority of omental GISTs were large and high risk. Mitotic index was risk factor for prognosis of omental GISTs. The prognosis was comparable between omental and gastric GISTs.

Plexiform fibromyxoma with cotyledon-like serosal growth: A case report of a rare gastric tumor and review of the literature

Plexiform fibromyxoma is a rare, benign mesenchymal neoplasm that predilects the gastric antrum and has potential for misdiagnosis as a gastrointestinal stromal tumor (GIST). The histology of the tumor is characterized by interwoven fascicular growth of cytologically bland spindled cells within a variably myxoid stroma. The current study reports the clinicopathological and immunohistochemical findings of a plexiform fibromyxoma resected from a 28-year-old Vietnamese female. The patient presented with acute, severe abdominal pain and worsening anemia. The initial fine-needle aspiration and needle core biopsy of the gastric antral mass led to an initial diagnosis of GIST. The subsequent distal partial gastrectomy revealed a 5.5-cm transmural antral mass that ulcerated the overlying mucosa and grew as variably elongated, myxoedematous, polypoid (cotyledon-like) excrescences from the serosal surface. Microscopically, the tumor demonstrated plexiform and multinodular growth of cytologically bland spindled cells proliferating in an abundant myxocollagenous stroma with a prominent capillary network. Tumor cells immunohistochemically expressed smooth muscle actin and CD10, but did not express CD117, Discovered on GIST-1 or nuclear β-catenin. Follow-up evaluation 23 months post surgery revealed no evidence of residual tumor. A review the cases of this rare entity reported in the English language literature is also provided.

Extra-Gastrointestinal Stromal Tumor of the Greater Omentum: Unusual Case Report

Gastrointestinal stromal tumors are the most common mesenchymal tumors of the gastrointestinal tract, originating from the interstitial cells of Cajal and most frequently expressing CD-117, a C-kit proto-oncogene, which can be detected immunohistochemically. Extra-gastrointestinal stromal tumors are neoplasms with similar immunohistological features arising outside the gastrointestinal tract with no connection to the gastric or intestinal wall.We report the case of a 61-year-old Moroccan man who presented with chronic abdominal pain along with progressive abdominal distension for the past last year. The clinical examination demonstrated a large abdominal mass and an abdominal computed tomography scan revealed a voluminous intraperitoneal mass measuring 30 cm in its greatest diameter. At laparotomy, this mass seemed to be arising from the greater omentum without continuity to the gastrointestinal tract. The mass was completely removed with clear margins and pathological examination was suggestive for high-risk gastrointestinal stromal tumor of the greater omentum. Due to the aggressive nature of this patient's tumor, he was assigned to receive imatinib as adjuvant chemotherapy for 3 years. He remains alive without any sign of recurrence after 4 years of follow-up.Extra-gastrointestinal stromal tumors of the greater omentum can grow slowly and remain clinically silent despite the large size of the tumor. Complete surgical resection is the only effective treatment approach. Nevertheless, adjuvant therapy following resection with imatinib has become a standard of care in cases of high risk disease.

Extragastrointestinal stromal tumor of lesser omentum: a challenging radiological and histological diagnosis

Extragastrointestinal stromal tumors (EGISTs) are a rare subgroup of gastrointestinal stromal tumors (GISTs), arising from outside the walls of gastrointestinal tubular organs. We report a case of an EGIST of the lesser omentum that represented a diagnostic challenge. Due to its atypical radiologic findings, it was preoperatively mistaken for pedunculated hepatic hemangioma. Histopathologically, it showed epithelioid structure and c-kit negative, very uncommon for GIST. Only a few cases of EGISTs have been previously reported. We discuss imaging and histological features, emphasizing potential pitfalls.

Association of high expression of Groβ with clinical and pathological characteristics of unfavorable prognosis in gastrointestinal stromal tumors

GROβ (CXCL2) is a chemokine produced by endotoxin-treated macrophages that mediates inflammation and tumor development. However, little is known about GROβ expression in gastrointestinal stromal tumors (GIST) or the relationship between GROβ expression and clinical attributes of GIST. GROβ expression was examined via immunohistochemical staining of 173 GIST samples using tissue microarray. The relationship between GROβ expression and relevant patient and tumor characteristics was assessed, using chi-square tests. Univariate and multivariate analysis was carried out using the Cox regression method. High GROβ cytoplasm staining was detected in 56 (32.4%) specimens; high GROβ nuclear staining was detected in 64 (37.0%) specimens. High GROβ cytoplasm staining was significantly associated with patients' age (P = 0.043) and tumor location (P = 0.014), while high GROβ nucleus staining was significantly associated with mitotic index (P = 0.034), tumor location (P = 0.049), and AFIP-Miettinen risk classification (P = 0.048). Kaplan-Meier survival curves showed GIST patients with low GROβ cytoplasm expression (P = 0.023) and mitotic index < 6 per 50 HPFs (P = 0.026) to have a more favorable prognosis. These findings indicate that GROβ expression correlates with malignant GIST phenotypes and could be an unfavorable prognostic marker in patients with GIST.

Gastrointestinal stromal tumor: recent advances in pathology and genetics

The discovery of KIT gene mutation in gastrointestinal stromal tumor (GIST) has provided a paradigm shift in the classification, diagnosis and molecular-targeted therapy of gastrointestinal mesenchymal tumors. There is growing evidence of phenotype-genotype (KIT, platelet-derived growth factor receptor-alpha, succinate dehydrogenase or other driver gene mutation) and genotype-therapeutic (sensitivity to imatinib) correlations in GIST. Risk stratification based on mitotic counts, tumor size and rupture is useful for the prognostication and management of patients with GIST. Blood vessel invasion is a strong indicator of liver metastasis in GIST. In addition, novel biomarkers such as cell-cycle regulators, microRNAs and their targets have been discovered by using high throughput molecular analyses. In contrast, leiomyosarcoma of the gastrointestinal tract has become a very rare entity in the 'KIT' era, and its molecular pathogenetic mechanism is unclear. Recent studies have revealed a wide spectrum of cytological atypia, mitotic counts and biological behavior of gastrointestinal smooth muscle tumors, suggesting the necessity of establishing the criteria for malignancy. Collectively, both classical histopathological procedures and modern molecular investigations are indispensable for the evolution of diagnosis and treatment of GIST and mimics.

Primary extragastrointestinal stromal tumour of the whole abdominal cavity, omentum, peritoneum and mesentery: a case report and review of the literature

Introduction

The gastrointestinal stromal tumour is one of the common mesenchymal tumours of the gastrointestinal tract. It originates from the interstitial cells of Cajal. Gastrointestinal stromal tumours that present outside the gastrointestinal tract are called extragastrointestinal stromal tumours; they share the same morphological and immunohistochemical characteristics. Here we describe an unusual case of extragastrointestinal stromal tumour that presented with gooseberry-like multiple nodules involving the whole abdominal cavity.

Case presentation

A 65-year-old Sudanese man presented with vague abdominal pain and progressive abdominal distension for 6 months. The pain was associated with mild loss of weight despite good appetite. A physical examination revealed distended abdomen with multiple firm nodules involving his whole abdomen. The results of haematological tests were within normal range. Ultrasound of his abdomen showed multiple nodules of varying sizes in the peritoneal cavity. A computed tomography scan of his abdomen showed numerous nodules of different sizes (1 to 3cm in diameter) filling the whole peritoneal cavity with intense peripheral enhancement. Ultrasound-guided biopsy was not informative. Upper and lower gastrointestinal endoscopies were normal. Exploration of his abdomen revealed multiple firm gooseberry-like nodules of different sizes involving the greater omentum, peritoneal cavity and the mesentery. The liver, spleen and pancreas were normal. The result of the histopathology was conclusive for gastrointestinal stromal tumour.

Conclusions

Here we present a rare case of extragastrointestinal stromal tumour in a patient who presented with vague abdominal pain and progressive abdominal distension. A laparotomy showed gooseberry-like multiple nodules of different sizes involving his whole abdominal cavity. He underwent debulking surgery and received imatinib.

Aggressive fibromatosis

Aggressive (deep or desmoid-type) fibromatoses are locally infiltrative collagen-forming tumours with potential for recurrence but not metastasis. They exert their clinical effects primarily in relation to location and have variable biological behaviour. In sporadic cases there are somatic mutations in the β-catenin (CTNNB1) gene on 3p21, resulting in immunohistochemically demonstrable overexpression in nuclei. Fibromatosis in patients with familial adenomatous polyposis (FAP) harbours inactivating germline mutations in the desmoid region of the adenomatous polyposis coli (APC) gene on 5q21-q22. The differential diagnosis includes other myofibroblastic lesions, perineurioma, low grade fibromyxoid sarcoma and, in the abdomen, gastrointestinal stromal tumour and liposarcoma with 'low-grade' dedifferentiation. The primary management is surgical, though some desmoids cease to grow and can be watched. Other therapies have a role in stabilising growth or shrinking tumours. Although no single therapy is effective in all cases, available modalities including irradiation, hormonal therapy, chemotherapy, and receptor tyrosine kinase inhibition can be of value in appropriate clinicopathological subgroups.

An extragastrointestinal stromal tumor in the omentum with peritoneal seeding mimicking an appendiceal mucinous cancer with carcinomatosis

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. These tumors tend to present most frequently in the stomach, followed by the small intestine. GISTs can also arise from the omentum, retroperitoneum, mesentery, or pleura and are termed extragastrointestinal stromal tumors (EGISTs) when they do so. EGISTs arising from the omentum are very rare. Due to the limited incidence of EGISTs in the omentum, the diagnostic criteria are not well established, and making a correct diagnosis may be difficult. In this report, we present a case of an EGIST of the omentum with peritoneal metastasis that was initially suspected to be an appendiceal mucinous carcinoma with carcinomatosis on positron emission tomography/computed tomography imaging.

Spontaneous perforation of jejunal gastrintestinal stromal tumour (gist). Case report and review of literature

GIST is the commonest mesenchymal tumour of the gastrointestinal tract. Jejunal GIST is rare and spontaneous perforation of asymptomatic jejunal GIST is unique. A review of the English literature reveals only fifteen cases of perforated GIST till date. Pre-operative diagnosis is difficult. Diagnosis is confirmed on histopathology and immuno-histochemistry. Complete removal with postoperative imatinib therapy entails optimal treatment. Perforated GIST is associated with high recurrence.

Pathology of gastrointestinal stromal tumors

Gastrointestinal stromal tumor (GIST) is a well recognized and relatively well understood soft tissue tumor. Early events in GIST development are activating mutations in KIT or PDGFRA, which occur in most GISTs and encode for mutated tyrosine receptor kinases that are therapeutic targets for tyrosine kinase inhibitors, including imatinib and sunitinib. A small minority of GISTs possessing neither KIT nor PDGFRA mutations may have germline mutations in SDH, suggesting a potential role of SDH in the pathogenesis. Immunohistochemical detection of KIT, and more recently DOG1, has proven to be reliable and useful in the diagnosis of GISTs. Because current and future therapies depend on pathologists, it is important that they recognize KIT-negative GISTs, GISTs in specific clinical contexts, GISTs with unusual morphology, and GISTs after treatment. This review focuses on recent developments in the understanding of the biology, immunohistochemical diagnosis, the role of molecular analysis, and risk assessment of GISTs.

Current management of gastrointestinal stromal tumors--a comprehensive review

BACKGROUND

Gastrointestinal stromal tumors (GISTs) comprise < 1% of all gastrointestinal (GI) tumors, but GISTs are the most common mesenchymal tumors of the GI tract. Dramatic changes in clinical practice have been observed in the last decade. This review highlights the overall management of GIST and its recent developments.

METHOD

We identified literature by searching Medline and PubMed from January 1995 to December 2011 using the keywords "gastrointestinal stromal tumors", "GIST", "imatinib" and "tyrosine kinase inhibitor". Additional papers were identified by a manual search of the references from the key articles. There were no exclusion criteria for published information to the topics.

RESULTS

For localized primary GISTs, surgical resection is the mainstay of therapy. The 5-year survival rate after complete resection of GISTs is approximately 50%-65%. Many factors including tumor size, mitotic rate, tumor location, kinase mutational status and occurrence of tumor rupture have been extensively studied and proposed to be predictors of survival outcomes. Adjuvant imatinib is proposed as an option for those patients with a substantial risk of relapse. Unresectable metastatic or recurrent GIST can be treated with a tyrosine kinase inhibitor, imatinib, with a remarkable response (50%-70%) and prolonged survival (median progression-free survival: 18-20 months; median overall survival: 51-57 months). The standard approach in the case of tumor progression on 400 mg once per day is to increase the imatinib dose to 400 mg twice per day as permitted by toxicity. Use of a second-line targeted agent, sunitinib, in patients with advanced GIST who fail (or are intolerant of) imatinib therapy is advised.

CONCLUSION

Treatment for GISTs has become increasingly complex because of the growing understanding of its biology. A multidisciplinary team that includes radiologists, medical oncologists, pathologists, and surgeons is paramount for the effective treatment of GIST.

Greater omentum gastrointestinal stromal tumor with PDGFRA-mutation and hemoperitoneum

Although gastrointestinal stromal tumor (GIST) occurs generally in the digestive tract, omental GIST is very rare. We report the first case of an adult greater omental GIST with a new platelet-derived growth factor receptor α gene (PDGFRA)-mutation with hemoperitoneum. A 43-year-old man was admitted to our hospital complaining of acute abdominal pain. Abdominal contrast-enhanced computed tomography revealed a huge mass in the right abdominal cavity, and a large accumulation of fluid in the pelvic cavity, suggesting hemoperitoneum. We diagnosed the rupture as an intra-abdominal tumor, and an emergency tumorectomy was performed with resection of the greater omentum. This tumor was located in the distal right side of the greater omentum, and showed no continuity with the gastric wall. The tumor occurred primarily in the greater omentum. The resected tumor was about 19 cm × 12 cm × 14 cm in diameter, and weighed 1529 g. Histologically, the tumor was composed of epithelioid-shaped cells with high cellularity, and was positive for CD117 and CD34, and negative for S-100, α-smooth muscle actin. The mitosis was 6/50 under high power field. This case showed exon 18 mutation of PDGFRA with 846 (Asp to Glu) substitution, 848 (Asn to Lys) substitution. This is the first report of this PDGFRA mutation in omental GIST, and this might play an important role in the tumorigenesis of this case. Based on these findings, the tumor was diagnosed as high risk GIST primarily occurring in the greater omentum. The patient was treated with imatinib at a dose of 400 mg/d as adjuvant chemotherapy, and has been followed up for 24 mo with no evidence of recurrence.

Predictors of response to targeted therapies for gastrointestinal stromal tumors

CONTEXT

The inhibition of oncogenic kinase signaling is a successful strategy to treat both hematologic and solid malignancies. Patients with chronic myelogenous leukemia, lung adenocarcinoma, renal cell carcinoma, and gastrointestinal stromal tumors are experiencing tremendous clinical benefits from targeted therapies in the form of kinase inhibitors. These drugs marked a revolution in cancer treatment, not only for their safety and efficacy, but also because they continue to expand our knowledge of the pathophysiology of cancer.

OBJECTIVE

To provide a summary of the biologic predictors of gastrointestinal stromal tumor behavior and response to targeted therapies that currently help guide clinical decision making.

DATA SOURCES

Published articles pertaining to the diagnosis, molecular genetics, prognostication, clinical behavior, and treatment of gastrointestinal stromal tumors, as well as experiences in a multidisciplinary sarcoma clinic.

CONCLUSIONS

In gastrointestinal stromal tumors, the strongest predictor of response to targeted therapies is the mutational status of KIT or PDGFRA. Patients whose tumors harbor a KIT exon 11 mutation benefit the most from imatinib mesylate therapy, in terms of response rate, progression-free survival, and overall survival. Conversely, tumors without detectable mutations in either gene ("wild-type" gastrointestinal stromal tumors) are generally not responsive to imatinib mesylate.

Histopathology of gastrointestinal stromal tumor

Gastrointestinal stromal tumor (GIST), generally driven by oncogenic KIT or PDGFRA mutations, is the most common mesenchymal tumor of the gastrointestinal (GI) tract. GIST is most common in the stomach (60%) and small intestine (30%), but can occur anywhere in the GI-tract and the intra-abdominal soft tissues. GIST can show spindle cell or epithelioid morphology, and mitotic count and tumor size are most important prognostic parameters. GISTs in NF1 patients and children are distinctive clinicopathologic groups. Immunohistochemical testing for KIT and sometimes for DOG1/Ano 1 is essential in confirming the diagnosis.

Prognostic factors for survival post surgery for patients with gastrointestinal stromal tumors

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms located in the alimentary tract. Our aim was to assess the influence of prognostic factors on survival in patients surgically treated for GISTs.

STUDY

One hundred and five patients treated between January 1989 and December 2008 were available for study. A retrospective analysis of prognostic factors (age, gender, mitotic index, tumor location, tumor size, risk of malignant behavior, and coexisting other neoplasm) was performed. Univariate and multivariate survival analyses were undertaken.

RESULTS

Univariate analyses revealed the importance of patient gender (p = 0.007), disease location (p = 0.055), mitotic index (p = 0.054) and coexistence with other neoplasms (p = 0.004). However, multivariate analysis showed 3 independently statistically significant factors: coexistence with other neoplasm (RR = 3.53, p = 0.004), male gender (RR = 2.60, p = 0.011) and mitotic index ≥10/50 HPF, (RR = 2.60, p = 0.042).

CONCLUSIONS

Our study has shown that male gender, a high mitotic index ≥10/50 HPF, and coexistence with other malignant neoplasms were independent poor prognostic factors in patients with GIST. The presence of middle or lower gut disease location leads to an increased risk of mortality when compared with the upper gut.

Epithelioid gastrointestinal stromal tumor of the stomach mimicking extragastrointestinal origin

We report a case of gastrointestinal stromal tumor (GIST) of the stomach mimicking extragastrointestinal origin. The tumor presented as a large isolated mass in the transverse mesocolon with a minor adhesion to the stomach. Microscopic examination revealed c-kit gene protein product (KIT)-positive tumor cells with epithelioid features. The tumor pseudocapsule close to the adhesion site included a small smooth muscle tissue component, indicating a gastric origin. Furthermore, tumor cells at the adhesion site showed prominent hyalinization and calcification. The tumor was diagnosed as a gastric GIST showing extensive extramural growth. Thus, GIST of the stomach and other parts of the gastrointestinal tract can present as tumors localized in the soft tissues of the abdomen mimicking extragastrointestinal origin.

Secondary resistance of extra-gastrointestinal stromal tumors to imatinib mesylate: report of a case

Extra-gastrointestinal stromal tumors (EGISTs) that do not originate in the digestive tract are rare. We report a case of multiple EGISTs, which was monitored closely by KIT gene mutation analysis and other investigations. The patient was a 52-year-old man in whom multiple tumors in the abdominal cavity were diagnosed as EGISTs. Immunohistochemical analysis revealed positive staining for c-kit; however, no mutations were found in the KIT gene. The tumors decreased in size remarkably following treatment with imatinib mesylate, but after 2 years of this treatment, multiple liver metastases and some regrowth of the abdominal masses were found simultaneously. The liver metastasis and the abdominal masses were excised, and further analysis of the KIT gene revealed the same mutation in exon 11 in the KIT gene in the metastatic tumors. We speculate that the treatment might have triggered development of the imatinib mesylate-resistant clone, which may have existed in the primary lesion as a KIT gene mutant. This report provides valuable insight into the mechanisms of recurrent GISTs after treatment with imatinib mesylate.

Extragastrointestinal stromal tumor originating from the vulva

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. They have gain-of-function mutations of the c-kit receptor tyrosine kinase gene and have been suggested to originate from the interstitial cells of Cajal. A small percentage of GISTs form extragastrointestinal masses. We report a rare case of a GIST originating from the vulva. A 55-year-old woman presented with a vulvar tumor. The tumor was initially diagnosed as a leiomyosarcoma following the first resection. Following a second recurrence the patient was administered chemotherapy. A third recurrence occurred and the patient underwent a third resection. Histology revealed that a bundle of fibrous tumor cells had invaded the connected tissue and muscular coat, and some spindle-shaped and blunt-ended nuclei were detected. Furthermore, immunohistochemical evaluation revealed that the tumor cells exhibited strong and diffuse staining for c-kit and CD34. The recurrent tumor was diagnosed as a GIST and a reevaluation of the original specimens also revealed a GIST. The patient was treated with imatinib, and is currently healthy with no evidence of recurrence at 20 months after the last surgery.

Giant gastrointestinal stromal tumor presenting as a palpable abdominal mass: an unusual presentation

Gastrointestinal stromal tumors (GIST-) account for the majority of mesenchymal tumors arising within the gastrointestinal tract. GIST presenting as a palpable abdominal mass is extremely rare. We report four additional cases of a GIST presenting as an abdominal mass along with a pertinent review of the literature. Twenty five cases of GISTs presenting with an abdominal mass, including 4 cases discussed here, have been reported in the world literature since 2001. The mean duration of symptoms was 152.7 days. Twenty one of 25 (84%) patients received surgical resection. The mean tumor size was 17.2 cm, with an average mitotic index of 7.6 per 50 high power fields. Thirteen of 14 (92.9%) patients had a high-risk tumor. Five patients were disease-free at a mean followup of 11 months, 2 patients had stable disease and 2 patients had progressive disease, and one patient had a partial response. In conclusion, symptomatic patents have an increased incidence of high-risk tumors and metastases at presentation. Adjuvant therapy with imatinib improves disease-free survival in patients with large abdominal GIST tumors, but no change in overall survival was noted. Finally, GISTs should be considered in the differential diagnosis of an abdominal mass in an elderly patient.

Diagnosis of gastrointestinal stromal tumor (GIST) on transurethral resection of the prostate: a case report and review of the literature

Gastrointesinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract and they show differentiation towards interstitial cells of Cajal (ICC). Herein, we describe a case of a 60-year-old man presenting with symptoms mimicking adenomatous hyperplasia of the prostate that was subjected to repeated transurethral prostatectomies. Histologic and immunohistochemical examination showed a neoplastic process with characteristics consistent with GIST. Imaging studies confirmed a rectal origin of the tumor. Review of the literature revealed 20 cases of GISTs occurring in the prostate gland, either diagnosed as either primary GISTs or, more commonly, as rectal neoplasms extending to this organ. We add our case in this short list, emphasizing on the importance of inclusion of GISTs in the differential diagnosis of every spindle cell lesion encountered in the prostate.

[A case of primary extragastrointestinal stromal tumor presenting as peritoneal dissemination]

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract, but also occurs at a lower frequency in extra-gastrointestinal regions such as omentum, mesentery, retroperitoneum and undefined abdominal sites. This tumor is called extragastrointestinal stromal tumor (EGIST). EGIST is mostly diagnosed as a cystic mass, but rarely occurs as a disseminated abdominal tumor. We experienced a 70-year-old man with primary EGIST presenting as peritoneal dissemination. Abdominal CT showed diffuse peritoneal thickening with a large amount of ascites, but no definite mass lesion. Laparoscopic biopsy was performed and histologic findings showed tumor composed of epithelioid cells. In the results of immunohistochemical stains, the tumor showed positive reactivity with CD117 (c-kit), CD34, vimentin and actin, but negative reactivity with desmin and S-100 protein. On account of unresectability and histologic parameters of malignant behavior, he was started on imatinib.

Advances in clinicopathological classification and genotyping of gastrointestinal stromal tumors

In recent years, the discovery of new markers and advances in mutation detection technologies have made it easy to diagnose gastrointestinal stromal tumor (GIST). However, it is still difficult to predict the biological behavior of GIST. Currently, the most prevalent GIST classification systems, including the National Institutes of Health (NIH) consensus criteria for assigning risk to gastrointestinal stromal tumors (2008 Revision) and the International Union Against Cancer TNM classification of malignant tumors (2010 version), are based on tumor size, mitotic rate, tumor location, and presence of a tumor rupture or not. Molecular genetic studies have shown that genotype of GIST is closely related to tumor prognosis and response to imatinib mesylate.

Primary extragastrointestinal stromal tumor of the pleura: report of a unique case with genetic confirmation

Gastrointestinal stromal tumors (GISTs), the most common mesenchymal neoplasms of the tubular gastrointestinal tract, usually originate in the wall of the stomach or small intestine. Most GISTs harbor oncogenic mutations in either the KIT or platelet-derived growth factor receptor alpha (PDGFRA) tyrosine kinase receptor genes and show differentiation along the lines of the interstitial cells of Cajal. Rarely, GISTs arise primarily in the omentum, mesentery, or retroperitoneum, at which sites they are referred to as "extragastrointestinal stromal tumors" (EGISTs). However, primary intrathoracic GIST arising in the pleura or lung has not been previously reported. We describe herein, a 62-year-old male who presented with a pleural-based mass unrelated to the esophagus that was morphologically typical of a spindle-cell GIST, showing strong immunoreactivity for KIT and DOG1, and harboring an exon 11 mutation in KIT. Ten years after resection, the tumor recurred as multiple masses in the pleura and mediastinum and was marginally reexcised. The patient was then treated with adjuvant imatinib mesylate with no evidence of further recurrences 13 months later. This seems to be the first EGIST arising above the diaphragm. This case shows a potential diagnostic pitfall with therapeutic consequences.