Gastrointestinal stromal tumors and other mesenchymal lesions of the gut

Inflammatory myofibroblastic tumor in the liver after bone marrow transplantation: case report and literature review

Introduction

Inflammatory myofibroblastic tumor (IMT) is a rare low-grade malignant neoplasm in the liver. Timely diagnosis and treatment of IMT are challenging due to its atypical symptoms and imaging results.

Case report

We report a 46-year-old woman who presented to our hospital with persistent hyperpyrexia and discomfort in the right upper abdomen for 2 months post bone marrow transplantation. Radiological findings revealed a space-occupying lesion of uncertain nature in the liver. Since the histological examination of the biopsy specimen indicated IMT, she underwent surgical resection. Subsequently, the postoperative pathology confirmed the diagnosis of IMT. The patient's febrile condition subsided after the surgery. A magnetic resonance imaging (MRI) scan performed 8 months later showed no signs of recurrence.

Conclusion

IMTs are caused by genetic rearrangements. Diagnosing IMT can be challenging especially in this case as we had to differentiate the tumor from inflammatory diseases associated with bone marrow transplantation. Hence, a thorough pathological immunohistochemical examination is required to confirm its diagnosis. Local IMTs should be treated with radical surgical resection. In cases of distant metastasis or incomplete resection cases, chemotherapy, targeted therapy, or immunotherapy can be utilized. Regular follow-up is crucial for improving the patient's survival rate.

The development of a prediction model based on deep learning for prognosis prediction of gastrointestinal stromal tumor: a SEER-based study

Accurately predicting the prognosis of Gastrointestinal stromal tumor (GIST) patients is an important task. The goal of this study was to create and assess models for GIST patients' survival patients using the Surveillance, Epidemiology, and End Results Program (SEER) database based on the three different deep learning models. Four thousand five hundred thirty-eight patients were enrolled in this study and divided into training and test cohorts with a 7:3 ratio; the training cohort was used to develop three different models, including Cox regression, RSF, and DeepSurv model. Test cohort was used to evaluate model performance using c-index, Brier scores, calibration, and the area under the curve (AUC). The net benefits at risk score stratification of GIST patients based on the optimal model was compared with the traditional AJCC staging system using decision curve analysis (DCA). The clinical usefulness of risk score stratification compared to AJCC tumor staging was further assessed using the Net Reclassification Index (NRI) and Integrated Discrimination Improvement (IDI). The DeepSurv model predicted cancer-specific survival (CSS) in GIST patients showed a higher c-index (0.825), lower Brier scores (0.142), and greater AUC of receiver operating characteristic (ROC) analysis (1-year ROC:0.898; 3-year:0.853, and 5-year ROC: 0.856). The calibration plots demonstrated good agreement between the DeepSurv model's forecast and actual results. The NRI values ( training cohort: 0.425 for 1-year, 0.329 for 3-year and 0.264 for 5-year CSS prediction; test cohort:0.552 for 1-year,0.309 for 3-year and 0.255 for 5-year CSS prediction) and IDI (training cohort: 0.130 for 1-year,0.141 for 5-year and 0.155 for 10-year CSS prediction; test cohort: 0.154 for 1-year,0.159 for 3-year and 0.159 for 5-year CSS prediction) indicated that the risk score stratification performed significantly better than the AJCC staging alone (P < 0.001). DCA demonstrated the risk score stratification as more clinically beneficial and discriminatory than AJCC staging. Finally, an interactive native web-based prediction tool was constructed for the survival prediction of GIST patients. This study established a high-performance prediction model for projecting GIST patients based on deep learning, which has advantages in predicting each person's prognosis and risk stratification.

Gastric inflammatory myofibroblastic tumor: a case report

BACKGROUND

Inflammatory myofibroblastic tumor (IMT) of the stomach is an uncommon mesenchymal neoplasm. We present a case of gastric submucosal tumor (SMT) where the final diagnosis was IMT.

CASE PRESENTATION

A 69-year-old man presented with a 24-mm SMT on the posterior wall of the middle third of the stomach that was detected by screening upper gastrointestinal endoscopy. Abdominal contrast-enhanced computed tomography showed that the tumor was well-enhanced. Although endoscopic ultrasonography-guided biopsy was performed, the histological diagnosis was not confirmed preoperatively. Since the tumor was clinically suspected to be a gastrointestinal stromal tumor, we performed gastric wedge resection by laparoscopic-endoscopic cooperative surgery. Pathologically, proliferative spindle cells with a positive reaction for smooth muscle actin, negativity for c-kit, desmin, s-100, CD34, STAT-6, β-catenin and anaplastic lymphoma kinase 1 were identified. Hence, the tumor was finally diagnosed as an IMT originating from the stomach.

CONCLUSIONS

When an SMT of the stomach is identified, the possibility of gastric IMT should be considered.

Jejunal Intussusception Secondary to a Large Inflammatory Fibroid Polyp: A Case Report and Discussion of Differential Diagnosis

Inflammatory fibroid polyp (IFP), initially considered a reactive process, is now recognized as a benign mesenchymal neoplasm of the gastrointestinal tract. We report a case of a 68-year-old woman with medically refractory Crohn disease that presented with intussusception requiring surgical intervention. The resection revealed a jejunal mass consisting of a submucosal proliferation of bland spindle cells in a fibrous stroma infiltrated by numerous eosinophils. By immunohistochemistry, the lesion was positive for vimentin and negative for desmin, smooth muscle actin (SMA), S-100, CD117, DOG1, ALK (D5F3), Melan-A, HMB-45, CD34, and STAT6. Ki-67 proliferative index was low (<1%). The mass was classified as IFP by its characteristic morphology and associated eosinophilia. IFP should be considered in the differential diagnosis of adults with intussusception or bowel obstruction. Definitive treatment typically requires surgical resection of the involved bowel segment.

Gastrointestinal stromal tumors: a comprehensive radiological review

Gastrointestinal stromal tumors (GISTs) originating from the interstitial cells of Cajal in the muscularis propria are the most common mesenchymal tumor of the gastrointestinal tract. Multiple modalities, including computed tomography (CT), magnetic resonance imaging (MRI), fluorodeoxyglucose positron emission tomography, ultrasonography, digital subtraction angiography, and endoscopy, have been performed to evaluate GISTs. CT is most frequently used for diagnosis, staging, surveillance, and response monitoring during molecularly targeted therapy in clinical practice. The diagnosis of GISTs is sometimes challenging because of the diverse imaging findings, such as anatomical location (esophagus, stomach, duodenum, small bowel, colorectum, appendix, and peritoneum), growth pattern, and enhancement pattern as well as the presence of necrosis, calcification, ulceration, early venous return, and metastasis. Imaging findings of GISTs treated with antineoplastic agents are quite different from those of other neoplasms (e.g. adenocarcinomas) because only subtle changes in size are seen even in responsive lesions. Furthermore, the recurrence pattern of GISTs is different from that of other neoplasms. This review discusses the advantages and disadvantages of each imaging modality, describes imaging findings obtained before and after treatment, presents a few cases of complicated GISTs, and discusses recent investigations performed using CT and MRI to predict histological risk grade, gene mutations, and patient outcomes.

Metastatic Neoplasms Involving the Stomach

OBJECTIVES

Metastatic neoplasms involving the stomach are rare and diagnostically challenging if clinical history of malignancy is absent or unavailable. This study was designed to identify the tumors that most frequently metastasize to the stomach and the morphologic features that can provide clues to investigate the possibility of metastasis and predict the primary sites.

METHODS

All patients with metastatic neoplasms involving the stomach were included in the study. The H&E- and immunohistochemical-stained slides were reviewed, and all clinical, endoscopic, and radiologic information was recorded.

RESULTS

One hundred fifty patients, including 84 (56%) women and 66 (44%) men (mean age, 64 years), were identified. Gastric metastases were the initial presentation in 15% cases. Epithelial tumors (73.3%) comprised the largest group, followed by melanoma (20.6%), sarcomas (4%), germ cell tumors (1.3%), and hematolymphoid neoplasms (0.7%). Lobular breast carcinoma was the most common neoplasm overall in women, while in men, it was melanoma. Solid/diffuse growth pattern (75%) was more common compared with glandular morphology. The solid/diffuse category included lobular breast carcinoma (21.3%), melanoma (20.6%), and renal cell carcinoma (10.6%), while the glandular category was dominated by gynecologic serous carcinomas (7.3%) with papillary/micropapillary architecture.

CONCLUSIONS

Metastatic neoplasms should be considered in the differential diagnosis of gastric neoplasms, particularly those with a diffuse/solid growth pattern. Glandular neoplasms are difficult to differentiate from gastric primaries except for Müllerian neoplasms, which frequently show a papillary/micropapillary architecture.

Mesenchymal tumors of the stomach: radiologic and pathologic correlation

Mesenchymal tumors of the stomach are uncommon, with gastrointestinal stromal tumor (GIST) being the most common among them. Majority of the tumors may arise from cells of Cajal, smooth muscle cells, neural cells, totipotent stem cells, adipocytes or fibroblasts. Imaging plays an important role not only in staging but also in characterizing these tumors. Many of these tumors have characteristic imaging features. GISTs usually present as large cavitating and necrotic tumors with exophytic component. Presence of fat tissue within the tumor suggests a lipoma or a teratoma, early phase hyperenhancement indicates glomus tumor and hemangioma, and delayed contrast enhancement is seen in schwannoma. Their differentiation from epithelial tumors like carcinoma and neuroendocrine tumors is often possible based on the location (mesenchymal tumors are intramural), spread, morphological appearance and enhancement patterns. However, overlapping features exist between these tumors with imaging often being only suggestive. A biopsy is necessary for a definitive diagnosis in many cases.

Clinical and Molecular Characteristics of Rare Malignant Tumors of Colon and Rectum

The most frequent form of colorectal cancer is represented by adenocarcinoma being about 98% of tumor histological types. However, other rare histotypes can be found in colon and rectum (adenosquamous, goblet cell adenocarcinoma, lymphoma, medullary carcinoma, melanoma, mesenchymal, neuroendocrine, plasmacytoma, signet ring, squamous tumors). Altogether, these forms account for less than 2% of colorectal tumors. There are no specific diagnostic or therapeutic recommended approaches and most of the information available from literature derives from small and retrospective clinical series. In the present study, we provide a paramount and updated view on clinical and biologic characteristics of rare colorectal tumors.

Rare Finding of Inflammatory Fibroid Polyp of the Duodenum: A Complete Diagnostic and Pathological Workup

Inflammatory fibroid polyps (IFP) are solitary benign tumors rarely found in the gastrointestinal (GI) tract. Additionally, duodenal polyps are diagnosed incidentally. We present a case of a 51-year-old female admitted to the department with an initial diagnosis of duodenal polyp on gastroscopy, CT, and positron-emission tomography (PET). COVID-19 pandemics was the reason for delayed treatment which allowed the lesion to progress and almost double its size in an eight-month period. We performed conventional duodenotomy and excision of the polyp. Diseases like gastrointestinal stromal tumor (GIST), inflammatory myofibroblastic tumor, and inflammatory polyp of Crohn's disease must be considered in the differential diagnosis of IFP because they could be observed in the same location.

Primary inflammatory myofibroblastic tumor of stomach-report of a very rare case

Primary inflammatory myofibroblastic tumor (IMT) is a very rare tumor arising from stomach and it closely mimics gastric GIST. It usually affects the lung and found in children and young patients. The diagnosis of gastric IMT is usually done post-operatively by immunohistochemistry examination where it is seen that IMT is positive to SMA and vimentin. Complete surgical excision is the treatment of choice and local recurrence is usually seen in incompletely resected cases.

Extra-gastrointestinal stromal tumor presenting as a huge peritoneal mass and mimicking as mesothelioma - A case report

INTRODUCTION AND IMPORTANCE

Extra-gastrointestinal stromal tumors are group of soft tissue neoplasm, which originates outside the gastrointestinal tract comprising of less than 5% of the total gastrointestinal stromal tumors.

CASE PRESENTATION

A 67 years old male came with a history of vague abdominal pain, discomfort and loss of appetite. Per abdominal examination showed a palpable firm mass which was filling both the flanks. Radiological imaging revealed a large abdomino-pelvic mass with central necrotic areas. Exploratory laparotomy was done and the mass was excised intact from the sigmoid mesocolon. Histopathological diagnosis was given as extra-gastrointestinal stromal tumors.

CLINICAL DISCUSSION

Extra-gastrointestinal stromal tumor was first described by Miettinen et al. in 1999. The tumor can arise from the pleura, omentum, mesentery, retroperitoneum and prostate. The clinical presentation of the tumor depends on its location and the size of tumor. Patients with these tumors present with abdominal pain, followed by abdominal mass and distention. These tumors show pathological, immunohistochemical and molecular biological characters similar as that of gastrointestinal stromal tumor.

CONCLUSION

Extra-gastrointestinal stromal tumor is a rare tumor and can reach to a considerable large size before presenting with clinical symptoms especially if the tumor arises from the mesocolon. IHC study plays an important role to reach to the final diagnosis as the tumor can mimic mesothelioma in routine staining.

A large inflammatory fibroid polyp of the rectum removed by transanal excision

Inflammatory fibroid polyps (IFP) are rare benign lesions arising from the submucosa of the gastrointestinal tract, most commonly found in the stomach and small intestine. IFPs are very rarely found in the rectum, with only a few reported cases, and their presentation is quite varied. The patient is a 53 year old male who underwent routine screening colonoscopy, during which a lobular mass of the proximal rectum was discovered. The patient subsequently underwent an endoscopic ultrasound (EUS) with fine needle aspiration (FNA) biopsy. Pathology displayed scant spindle cells with benign glandular epithelium suspicious for a spindle cell neoplasm. The mass was excised transanally. The morphological and immunohistochemical findings supported the diagnosis of inflammatory fibroid polyp. Although this is not a malignant tumor, the treatment and surveillance guidelines have not been determined and there is no standard of care.

Effects of CO2 pneumoperitoneum on proliferation, apoptosis, and migration of gastrointestinal stromal tumor cells

BACKGROUND

The purpose of the study was to investigate the proliferation and migration capability of human gastrointestinal stromal tumor line GIST-T1 after exposure to different pressures and times of CO₂ pneumoperitoneum.

METHODS

We established simulated CO₂ pneumoperitoneum environment in vitro and divided the human GIST cell GIST-T1 into open control group, 8 mmHg CO₂ pneumoperitoneum treatment group and 15 mmHg CO₂ pneumoperitoneum treatment group. Each group was divided into two subgroups respectively cultured for 1 h and 3 h. pH value of cell culture, cell growth curve, and cell cycle distribution of each group was measured. By application of scratch healing tests and Transwell chamber experiments, mobility ratio and number of cells through 8 µm membranes were measured to assess the migration ability of cells in each group after intervention.

RESULTS

Cell culture pH value of each subgroup in CO₂ group decreased significantly after exposed in CO₂ pneumoperitoneum (P < 0.01). The proliferation of GIST-T1 cells in 15 mmHg CO₂ group was significantly inhibited early (1-2 days) (P < 0.05) and the proliferation of GIST-T1 cells in 8 mmHg CO₂ 1 h subgroup and 15 mmHg CO₂ 1 h subgroup was increased significantly late (4-6 days) (P < 0.05) after the interventions of CO₂ pneumoperitoneum. The percentage of cells in G0-G1 phase increased, the percentage of S phase cells decreased (P < 0.01) in 1-h subgroup and 3-h subgroup of 15 mmHg CO₂ group 24 h after exposure to CO₂. The percentage of cells in S phase increased in 1-h subgroup of 8 mmHg CO₂ group and decreased in 3-h subgroup of 15 mmHg CO₂ group 72 h after exposure to CO₂. In the Transwell chamber experiment, the cell number through 8-µm membrane increased significantly (P < 0.01) in 3-h subgroup of CO₂ group compared to that in 3-h subgroup of control group.

CONCLUSIONS

The routine pressure and duration of CO₂ pneumoperitoneum used in clinic did not promote the proliferation of gastrointestinal stromal tumors, but had a potential risk of increasing postoperative recurrence and distant metastasis.

Case of colonic mucosal Schwann cell hamartoma and review of literature on unusual colonic polyps

Mucosal Schwann cell hamartomas (MSCH) are benign mesenchymal tumours rarely seen in the gastrointestinal tract. They occasionally present as incidental sessile polyps during colonoscopy. A 55-year-old asymptomatic female patient with a medical history of multiple sclerosis presented for a screening colonoscopy. A 5 mm low-risk tubular adenoma was noted in the caecum, and a second 5 mm polyp was found in the ascending colon. Histopathology of the ascending colon polyp showed proliferation of spindle cells without ganglion cells in the lamina propria. Immunohistochemical findings are compatible with an MSCH. Surveillance colonoscopy was scheduled in 5 years based on the presence of a single low-risk tubular adenoma.

Ulcerated gastric leiomyoma causing massive upper gastrointestinal bleeding: A case report

Leiomyomas are rare, benign submucosal tumors originating from smooth muscle cells. The clinical presentation is usually asymptomatic, with excellent prognosis. We herein report the case of a 68-year-old female with a solitary leiomyoma found during esophagogastroduodenoscopy for hematemesis. Histopathological examination revealed smooth muscle proliferation supported by positive staining for smooth muscle myosin heavy chain and negative staining for CD117 and S-100, consistent with the marker expression pattern of leiomyoma. We report on the clinical presentation of this case, and discuss the origin, epidemiology, treatment and management of leiomyomas.

Gastric gastrointestinal stromal tumor with osseous differentiation and stromal calcification: A case report and review of literature

Gastrointestinal stromal tumors are the most common primary mesenchymal tumors of the gastrointestinal tract accounting for 0.1%–3.0% of all gastrointestinal malignancies. The stomach is the most common site (60%) followed by the small bowel (30%–35%) particularly jejunum and ileum, colorectum (5%) and rarely affect esophagus and appendix. Most gastrointestinal stromal tumors arise sporadically, however, less commonly they develop in association with various clinical syndromes like Carney triad, Carney–Stratakis syndrome, familial gastrointestinal stromal tumor syndrome and neurofibromatosis type1 (NF1). We report a 65-year-old male patient presented with gastric mass (7.5 × 4.5 × 3.5 cm) arising from the posterior gastric wall. Histologic examination revealed neoplastic proliferation of spindled and epithelioid cells with focal plexiform pattern and low mitotic activity 3/50 HPF. No evidence of cytological atypia, abnormal mitosis or necrosis. Interestingly enough, there were focal areas of mature bone formation/osseous differentiation associated with calcification. The tumor cells were strongly positive for CD117, DOG1 with focal immunoreactivity against CD34. The morphologic features and the immunoprofile were diagnostic of gastrointestinal stromal tumor. Herein, we present a rare case of gastric gastrointestinal stromal tumor with mature bone formation, osseous metaplasia and calcification. To the best of our knowledge, this is the second case report of gastric gastrointestinal stromal tumor with osseous differentiation and mature bone formation.

Gastric mesenchymal tumors as incidental findings during Roux-en-Y gastric bypass

BACKGROUND

Occurrences of mesenchymal tumors have been more recognized in recent years, and the incidental diagnosis of these lesions during bariatric surgery has been previously reported.

OBJECTIVE

To describe the cases of incidentally diagnosed mesenchymal tumors during consecutive bariatric surgeries.

SETTING

Private health-providing service, Brazil.

METHODS

A retrospective population-based study, which enrolled individuals who consecutively underwent Roux-en-Y gastric bypass at a single center from January 2006 through July 2016.

RESULTS

Of 1502 individuals, there were 16 cases (1.1%) of confirmed mesenchymal tumors. Of these 16 cases, 14 (87.5%) were gastrointestinal stromal tumors and 2 (12.5%) were leiomyomas. The affected individuals were significantly older (aged 46.2 ± 6.3 versus 35.4 ± 7.2 yr; P = .00031), presented a lower body mass index (38.2 ± 5.1 versus 45.3 ± 8.1 kg/m²; P<.00001), and had a lower weight (102.1 ± 17.9 versus 121.1 ± 7.4 kg; P = .00321). None of the individuals presented reported relapses of the mesenchymal tumors.

CONCLUSION

The possibility of incidental gastric mesenchymal tumors during bariatric surgery should not be neglected; a careful inventory of the stomach at the beginning of the procedure and resection of lesions found are mandatory. (Surg Obes Relat Dis 2017;X:XXX-XXX.) © 2017 American Society for Metabolic and Bariatric Surgery. All rights reserved.

Cytologic and Immunohistochemical Evaluation of Low-Grade Spindle Cell Lesions of the Gastrointestinal Tract

Spindle cell lesions of the gastrointestinal tract are relatively uncommon compared with the frequency of their epithelial counterparts. Although gastrointestinal stromal tumors and leiomyomas are the most commonly encountered spindle cell lesions in the stomach and esophagus, respectively, there are other less common diagnostic entities that should be considered for accurate diagnoses as well as appropriate patient treatment and clinical follow-up. Given the morphologic overlap of low-grade spindle cell lesions on cytologic preparations, ancillary studies play a key role in differentiating these lesions from one another.

Metastatic Liver Disease Associated with Gastrointestinal Stromal Tumors: Controversies in Diagnostic and Therapeutic Approach

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are the most frequent mesenchymal lesions of the GI tract. They are considered to originate from neoplastic transformation of either the intestinal pacemaker cells of Cajal or the precursor pluripotential stem cells. The genetic basis of GIST growth is an activating mutation of two receptor tyrosine kinases. Recent epidemiologic studies demonstrate that the GIST prevalence is approximately 20/1000000/year. Although GISTs develop in every part of the GI tract, stomach remains the most common localization. About 80 % of the patients experience tumor recurrence or hepatic metastasis after radical resection. GIST liver metastases are usually multiple, large in diameter, and localized in both lobes. In addition, GISTs are usually completely asymptomatic, discovered incidentally. Symptoms are not typical and depend on the location, size, and aggressiveness of the tumor.

DISCUSSION

Diagnostic evaluation is based on imaging techniques, such as computed tomography, magnetic resonance imaging, positron emission tomography, and endoscopic ultrasound. Despite recent research on the therapeutic strategies against GISTs, surgical resection appears the only potentially curative approach. For the advanced metastatic disease, imatinib, a tyrosine kinase inhibitor, has been proposed neoadjuvantly with the surgery performed after the adequate reduction of tumor burden. The aim of this review was to evaluate the results of surgical treatment for metastatic GIST with special reference to the extent of its histological spread and to present the recent literature in order to provide an update on the current concepts of advanced surgical management of this entity.

Gastrointestinal (GI) leiomyosarcoma (LMS) case series and review on diagnosis, management, and prognosis

This review of 76 gastrointestinal (GI) leiomyosarcoma (LMS) cases that include 11 cases from the American University of Beirut Medical Center represents, to our knowledge, the largest number of combined GI LMS cases reported. The age range of GI LMS is variable, and the presentation is non-specific, making pathological diagnosis essential. LMSs usually lack CD117 and CD 34 mutations and are usually positive for smooth muscle cell markers. The review highlights surgery as the mainstay of treatment with negative margins attained most of the times. Adjuvant chemotherapy is used in around 7-27 % of the cases mainly for small intestinal and colorectal LMS. The relatively small number of patients is a limitation on outcome analysis. However, LMS has a risk of recurrence reaching 39-80 % and secondary metastasis reaching 55-71 % in small intestinal and colorectal cases. In light of the high frequency of recurrence and metastasis, enrolling patients in clinical randomized trials to investigate the role of chemotherapy, radiation therapy, and targeted therapy is required for better control of this rare aggressive GI tumor.

Pancreatic Gastrointestinal Stromal Tumor after Upper Gastrointestinal Hemorrhage and Performance of Whipple Procedure: A Case Report and Literature Review

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in the gastrointestinal system. These types of tumors originate from any part of the tract as well as from the intestine, colon, omentum, mesentery or retroperitoneum. GIST is a rare tumor compared to other types of tumors, accounting for less than 1% of all gastrointestinal tumors.

CASE REPORT

A 56-year-old male patient was hospitalized due to an upper gastrointestinal hemorrhage and the start of abdominal pain on the same day. In the upper gastrointestinal endoscopy that was performed, a solitary mass was found in the second section of the duodenum and a blood vessel (Forrest type 2a) was seen. The extent and location of the mass was detected by abdominal tomography. After hemodynamic recovery, a Whipple procedure was performed without any complications. A subsequent histopathological examination detected a c-kit-positive (CD117) pancreatic GIST with high mitotic index.

CONCLUSIONS

The most effective treatment method for GISTs is surgical resection. In patients with a head of pancreatic GIST, the Whipple procedure can be used more safely and effectively.

Bortezomib enhances the therapeutic efficacy of dasatinib by promoting c-KIT internalization-induced apoptosis in gastrointestinal stromal tumor cells

Dasatinib-based therapy is often used as a second-line therapeutic strategy for imatinib-resistance gastrointestinal stromal tumors (GISTs); however, acquired aberrant activation of dasatinib target proteins, such as c-KIT and PDGFRβ, attenuates the therapeutic efficiency of dasatinib. Combination therapy which inhibits the activation of dasatinib target proteins may enhance the cytotoxicity of dasatinib in GISTs. Bortezomib, a proteasome inhibitor, significantly inhibited cell viability and promoted apoptosis of dasatinib-treated GIST-T1 cells, whereas GIST-T1 cells showed little dasatinib cytotoxicity when treated with dasatinib alone, as the upregulation of c-KIT caused by dasatinib itself interfered with the inhibition of c-KIT and PDGFRβ phosphorylation by dasatinib. Bortezomib induced internalization and degradation of c-KIT by binding c-KIT to Cbl, an E3 ubiquitin-protein ligase, and the subsequent release of Apaf-1, which was originally bound to the c-KIT-Hsp90β-Apaf-1 complex, induced primary apoptosis in GIST-T1 cells. Combined treatment with bortezomib plus dasatinib caused cell cycle arrest in the G1 phase through inactivation of PDGFRβ and promoted bortezomib-induced apoptosis in GIST-T1 cells. Our data suggest that combination therapy exerts better efficiency for eradicating GIST cells and may be a promising strategy for the future treatment of GISTs.

A rare case of giant gastrointestinal stromal tumor of the stomach involving the serosal surface

INTRODUCTION

Although rare, gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors affecting the gastrointestinal tract.

PRESENTATION OF CASE

Here we report the case of a 43-year-old man complaining of abdominal pain along with a painless and palpable mass, which was confirmed on magnetic resonance and multislice computed tomography. Laparotomy revealed a nodular grayish-white firm noninfiltrative mass (39×27×14cm, 6109g) that was well localized within the extramuscular and peritoneal surface of the anterior wall of the stomach; complete tumor resection was performed. Histopathological examination revealed features typical of GIST, including increased cellularity, increased mitotic activity, and spindle shaped cells as well as positive immunoreactivity for KIT, CD34, and vimentin.

DISCUSSION

A review of literature revealed that GISTs of the size and weight similar to the present case has been rarely reported. GIST most frequently involves the stomach. Although the etiopathogenesis of this disease remains unclear, few well-documented familial cases have been associated with GIST syndromes.

CONCLUSION

The primary treatment preferred is complete surgical excision of the tumor.

A Large Gastric Inflammatory Fibroid Polyp

Inflammatory fibroid polyp (IFP) is an unusual benign gastrointestinal subepithelial tumor (SET). The endosonographic (EUS) features of IFPs were sporadically reported on imaging tips or small case series study. However, the differential diagnosis and optimal treatment of gastric IFP is still challenging. We report an unusual case of a large erosioned and prolapsing gastric submucosal lesion, presenting primarily with obstructive symptoms ("ball valve syndrome") and anemia. On EUS examination, a 50 mm SET in the distal antrum was seen, with hypoechoic but heterogeneous echo-pattern, located in the second and third sonographic layers of the gastric wall (deep mucosal and submucosal). The fourth (muscle) layer was intact; no peri-lesional adenopathies were identified. A decision was made to proceed to endoscopic treatment because of the mentioned symptoms. Histopathologic evaluation of the resected specimen with immunohistochemical staining was consistent with the diagnosis of IFP. IFP rarely reach these large dimensions or cause symptoms. Despite its benign etiology, endoscopic resection was important in both establishing a histologic diagnosis and treatment. EUS was crucial in the differential diagnosis. The literature concerning IFP is also reviewed.

Perineurioma in the sigmoid colon diagnosed and treated by endoscopic resection

Perineuriomas are rare benign peripheral nerve sheath tumors in the gastrointestinal tract. We recently encountered a submucosal lesion in the sigmoid colon that was resected by endoscopic mucosal resection and was then diagnosed as perineurioma by immunohistochemistry. A 51-year-old female with a positive test for fecal occult blood was referred to our hospital for screening colonoscopy. Colonoscopy identified a submucosal lesion, approximately 15 mm in diameter, in the sigmoid colon. Endoscopic ultrasound showed a 15-mm tumor with a strong acoustic shadow. Endoscopic mucosal resection was performed in order to make a precise diagnosis as well as removal. The specimen revealed spindle cell proliferation without atypia, and immunostaining revealed that the spindle cells were positive for collagen type IV and glut-1, and the lesion was diagnosed as a colonic perineurioma with no malignancy. Gastroenterologists as well as pathologists should be aware of this type of submucosal lesion, and immunohistochemical evaluation is highly recommended when an unusual mesenchymal tumor is found.

Tactoid body features in a Schwann cell hamartoma of colonic mucosa

BACKGROUND

Mesenchymal colorectal polyps are uncommon lesions, particularly those of neurogenic origin. We describe a mucosal Schwann cell hamartoma of the colon with tactoid features, so far reported in peripheral nerve sheath tumours, and address its differential diagnosis and clinical implications.

CASE PRESENTATION

A 72-year-old man underwent screening colonoscopy that presented a 5-mm polyp on distal sigmoid. Histologically, it displayed a lesion in the lamina propria comprising oval structures with tactoid features and bland spindle cells, entrapping adjacent crypts. No ganglion cells were seen. Spindle cells expressed only S-100 protein and vimentin.

DISCUSSION

Mucosal Schwann cell hamartoma was recently recognized as distinct from common (submucosal) colorectal Schwannomas and so far not associated to inherited syndromes. Thus, it should be considered in the differential diagnosis of look-alike lesions (eg, ganglioneuroma, neuroma, and neurofibroma) that may occur in the setting of inherited syndromes such as Cowden syndrome, multiple endocrine neoplasia-2B, and type 1 neurofibromatosis.

Inflammatory fibroid polyps of the gastrointestinal tract: spectrum of clinical, morphologic, and immunohistochemistry features

Inflammatory fibroid polyps (IFPs) are rare, benign tumors that can arise throughout the gastrointestinal tract. Although the molecular pathogenesis of these lesions has been well characterized, their morphologic features often vary. We report the clinicopathologic findings of the largest series of IFPs to date. A total of 83 IFPs seen at our institution were collected between 1999 and 2012. The specimens included 64 biopsies and 19 resections. A review of the clinical features identified a modest female predominance (47 women and 36 men) with patients ranging in age from 26 to 87 years (mean, 60 y). Involved sites included the esophagus (n=2), stomach (n=31; mainly antrum), small intestines (n=17), appendix (n=1), large intestines (n=31; majority within the rectosigmoid), and anal canal (n=1). Although most patients had a nonspecific presentation, those with small intestinal lesions frequently presented with intussusception. Grossly, the tumors ranged in size from 0.2 to 4.2 cm (mean, 1.7 cm). Histologically, IFPs were centered within the submucosa in all resection specimens, but mucosal extension was found in 74 of 83 (89%) cases. The tumors varied in both cellularity and degree of vascularity. However, the characteristic feature of perivascular onion skinning was present in only 54% (45/83) of the cases. In addition, a short fascicular growth pattern was also noted in 36% (30 of 83) of cases, whereas both features were present in 14 cases (17%). Eosinophils were present in 94% (78 of 83) of cases but varied widely in number from abundant (20/hpf) to sparse (1/hpf). Interestingly, in those cases with sparse eosinophils, prominent hyalinization was also present (11 of 78, 13%). In addition, although the majority of IFPs expressed CD34, 6 of 44 (14%) were negative. No associated dysplasia or malignancy was seen. IFPs represent a diverse set of submucosal-based lesions that commonly extend into the mucosa, making them amenable to endoscopic biopsy. Although their classic histologic features of perivascular onion skinning and predominance of eosinophils are well described, they may alternatively present with a short fascicular growth pattern, a sparse number of eosinophils, and prominent hyalinization.

Colonic inflammatory myofibroblastic tumours: an institutional review

AIM

The aim of the study was to present the largest series of colonic inflammatory myofibroblastic tumour (C-IMFT) in the literature so far and to provide a review of this condition.

METHOD

A retrospective review was carried out of a consecutive series of patients diagnosed with a C-IMFT at a community-based hospital with a specialized gastrointestinal unit between 2002 and 2011. The main outcome measures were success rate and postoperative complications. Using a set of terms we searched the PubMed database for papers published on C-IMFT. We reviewed the data from these studies and case reports.

RESULTS

There were seven patients with a histopathologically proven C-IMFT. The patients' mean age was 39 ± 11.3 years. Four presented with clinical features of intestinal obstruction of varying severity and three with symptoms of anaemia. Complete surgical resection with end-to-end anastomosis was performed. The gross morphology included polypoidal myxoid tumours that served as a lead point for intussusception in two cases, a whorled mass in two and a circumferential infiltrative tumour in three. Microscopically, all tumours had typical features of IMFT with a variable expression of anaplastic lymphoma kinase (ALK-1) and tumour-free resection margins. All patients were well without local recurrence or metastasis at a mean follow-up of 46.8 ± 11.9 months.

CONCLUSION

Surgical resection is effective for this rare tumour which mostly behaves in a benign manner. Our review supports the need for patients to be followed up for long periods because of the possibility of metastasis or late recurrence.

Inflammatory myofibroblastic tumor: a rarely seen submucosal lesion of the stomach

Inflammatory myofibroblastic tumor (IMT) is a rare mesenchymal benign tumor which is generally seen in children and in young adults. It is especially located in the lungs. In histopathological examination, neoplastic fusiform cells originating from a subtype of accessory immune system cells which are called fibroblastic reticulum cells are seen (Kouichi and Youichirou, 2008). Although IMT is histopathologically benign, imaging methods show its tendency for local recurrence and invasion. In most of the cases, it may not be possible to make a distinction whether it is malign or benign. Complete surgical resection is the most important treatment method. In this study, we have discussed the findings of our case having a gastric submucosal located IMT in light of the current literatures.

Immunohistochemical features of the gastrointestinal tract tumors

Gastrointestinal tract tumors include a wide variety of vastly different tumors and on a whole are one of the most common malignancies in western countries. These tumors often present at late stages as distant metastases which are then biopsied and may be difficult to differentiate without the aid of immunohistochemical stains. With the exception of pancreatic and biliary tumors where there are no distinct immunohistochemical patterns, most gastrointestinal tumors can be differentiated by their unique immunohistochemical profile. As the size of biopsies decrease, the role of immunohistochemical stains will become even more important in determining the origin and differentiation of gastrointestinal tract tumors.

Extra-gastrointestinal stromal tumor of the omentum: a rare case report and review of the literature

Gastrointestinal stromal tumors (GIST) are uncommon mesenchymal spindle-cell or epithelioid neoplasms, located mainly with higher frequency in the stomach and small bowel. GISTs represent the majority of primary non-epithelial neoplasms of the digestive tract, most frequently expressing the KIT protein a transmembrane tyrosine kinase receptor for stem cell factor. Extra-gastrointestinal stromal tumors tend to present In fewer than 5% of cases; they originate primarily from the mesentery, omentum or peritoneum. Furthermore, these extra-gastrointestinal tumors (EGIST) tend to be more common in patients over the age of 50 years. EGISTs are neoplasms with overlapping immunohistological features, occurring in the abdomen outside the gastrointestinal tract with no connection to the gastric or intestinal wall. We describe here a rare case of EGIST of the lesser omentum and report the clinical, macroscopic, immunohistological and radiological features of an EGIST arising in the lesser omentum of a 63-year old man. Clinical course and the prognostic factors of such lesions will also be discussed. EGISTs in the lesser omentum can grow slowly and remain silent despite a large tumor size. In most cases, a pre-operative diagnosis is not possible, and the patient undergoes a surgical operation for the generic diagnosis of abdominal mass. During the intervention it is important to achieve a complete removal of the mass and to examine every possible adhesion to the gastrointestinal wall.

Leiomyosarcoma of the sigmoid colon with multiple liver metastases and gastric cancer: a case report

Background

Leiomyosarcoma (LMS) of the gastrointestinal tract is an extremely rare high-grade neoplasm with poor prognosis. For advanced LMS with distant metastasis, the decision as to the choice of the most appropriate therapeutic strategy, including chemotherapy and surgery, is difficult. Here, we present an unusual case of LMS of the sigmoid colon with liver metastases and gastric cancer. The survival of this patient was prolonged by a combined modality therapy involving chemotherapy and surgery.

Case presentation

A 66-year-old woman who had been diagnosed with advanced gastric cancer and multiple liver metastases was referred to our hospital. The initial treatment with docetaxel and S-1 considerably reduced both the gastric cancer and liver tumors; consequently we performed surgical resection. Pathological examination revealed that no viable tumor cells remained in the stomach and chemotherapy resulted in complete remission of the gastric cancer. The liver tumors were immunohistochemically diagnosed as LMS. A tumor of the sigmoid colon was subsequently discovered and the liver tumors were found to have recurred. The surgically resected sigmoid colon and liver tumors were all immunohistochemically diagnosed as LMS. These findings indicated that the multiple liver metastases arose from the LMS in the sigmoid colon, and that they were accompanied by advanced gastric cancer. We performed another surgical resection and administered chemotherapy to treat the recurring liver metastases. The patient survived for 4 years and 10 months after initial presentation at our hospital.

Conclusion

Colonic LMS is rare and its joint occurrence with gastric cancer is extremely unusual. Although LMS is a high-grade neoplasm, a multimodal therapeutic approach can increase patient survival time even when multiple liver metastases are present.

Potential indicators predict progress after surgical resection of gastrointestinal stromal tumors

In order to find out the potential indicators predicting prognosis of malignant gastrointestinal stromal tumors (GISTs) after surgical resection, we collected clinical records of 80 patients with malignant GISTs. Tumor location, size, mitotic index, necrosis were compared with the prognosis of malignant GISTs by Kaplan-Meier method and log-rank test. After a median follow-up of 844 days (52-2 145), we found that as National Institutes of Health suggested, tumors with intermediate risk had more favorable prognosis than that with high risk. Their 3-year survival rate were 65.3% and 41.3%, respectively (P < 0.001). Moreover, tumor size and mitotic index were associated with free survival. The 3-year survival rate for patients with tumor size ≤ 10 cm and > 10 cm were 62.3% and 41.8%, respectively (P = 0.002), Tumors with mitotic index ≤ 5/50 HPF had a higher 3-year survival rate than tumors with mitotic index > 5/50 HPF (67.1% versus 40.7%, P = 0.005). The presence of necrosis was directly related to the malignant behavior. The 3-year survival rate for presence and absence necrosis were 50.8% and 64.8% (P = 0.008). From the present study, we can conclude that besides tumors size and mitotic index, tumor location and necrosis also influence on the long-term survival of patient with malignant GISTs after surgical resection.

Inflammatory myofibroblastic tumor in colon

Inflammatory myofibroblastic tumor (IMT) is an uncommon mesenchymal solid tumor commonly documented in children and young adults. Here, we report a case of IMT in colon confirmed pathologically after laparoscopic anterior resection. A 35-year-old man presented with anal bleeding after defecation for 2 weeks. Colonoscopy demonstrated a mass with shallow ulceration in the central area and irregular margin accompanied by intact mucosa in the descending colon. Computer tomography showed a well-demarcated and homogenous solitary mass in the descending colon. We performed laparoscopic anterior resection. This case was diagnosed as IMT after microscopic examination. The tumor was composed of a proliferation of spindle-shaped cells arranged in the hyaline material with chronic inflammatory cells, composed mainly of plasma cells and lymphocytes. Immunohistochemically, tumor cells were positive for smooth muscle actin, and vimentin, and negative for desmin, CD117 (c-kit), anaplastic lymphoma kinase-1.

Laparoscopically assisted resections of small bowel stromal tumors are safe and effective

OBJECTIVE

To compare the efficacy of laparoscopically assisted and open resections in treatment of small bowel stromal tumors (SBST).

METHODS

A retrospective study of 85 patients who underwent curative resections for SBST (38 by laparoscopically assisted procedures and 47 by open procedures) was performed.

RESULTS

There were no differences between open and laparoscopically assisted approaches in terms of patients' age, gender, presenting symptoms, histological risk or extent of resection (P > 0.05). The median tumor size for laparoscopically assisted resections was 4.0 cm (range 1.2-7.0 cm), which was the same as that for the open resections (range 2.0-10.0 cm). There were fewer complications in the laparoscopic group than those in the open resection group (7.9% vs 17.0%), but no significant difference was observed (P > 0.05). The 2-year survival of the two patient groups was almost the same (86.8% vs 89.4%). Laparoscopically assisted procedures required on average 22.5 min less of operating time (87.5 min vs 110.0 min, P = 0.006), 1.0 day less of bowel recovery time (3.0 days vs 4.0 days, P = 0.001) and 5.0 days less in hospital stay (8.0 days vs 13.0 days, P < 0.001).

CONCLUSION

Laparoscopically assisted resection of SBST is a safe alternative to open resection.

Schwann cell hamartoma: case report

Background

Colorectal polyps of mesenchymal origin represent a small percentage of gastrointestinal (GI) lesions. Nevertheless, they are encountered with increasing frequency since the widespread adoption of colonoscopy screening.

Case presentation

We report a case of a small colonic polyp that presented as intramucosal diffuse spindle cell proliferation with a benign cytological appearance, strong and diffuse immunoreactivity for S-100 protein, and pure Schwann cell phenotype. Careful morphological, immunohistochemical and clinical evaluation emphasize the differences from other stromal colonic lesions and distinguish it from schwannoma, a circumscribed benign nerve sheath tumor that rarely arises in the GI tract.

Conclusion

As recently proposed, this lesion was finally described as mucosal Schwann cell hamartoma.

Malignant solitary tumor in a child: a case report and review of the literature

Solitary fibrous tumor in the mesentery is rare. We report a case of a malignant solitary fibrous tumor in the appendical mesentery of 6-year-old boy. Computed tomography and ultrasound of the abdomen demonstrated a well-defined solid mass, 4.0 cm in diameter, in the lower right abdomen. At laparotomy, an encapsulated tumor was observed in the appendical mesentery and was easily separated from the appendix. Immunohistochemistry stain showed that the spindle-shaped cells were positive for CD34 and neuron-specific enolase. DOG-1, CD117, desmin, S-100 protein, and SMA were negative. The sequence of KIT and platelet-derived growth factor receptor α was presented with wild type, no mutation. The patient received the reoperation 5 months postoperation. Despite these treatments, the relapsed tumor rapidly and markedly enlarged. The patient died of recurrent tumor with liver dissemination 7 months after reoperation.

Gastrointestinal Mesenchymal Neoplasms other than Gastrointestinal Stromal Tumors: Focusing on Their Molecular Aspects

Gastrointestinal (GI) mesenchymal tumors other than gastrointestinal stromal tumor (GIST) are rare neoplasms, but they often enter the differential diagnosis of more common GI lesions. Some of these mesenchymal tumors in the GI tract have well understood molecular pathologic aspects, including desmoid tumors, inflammatory myofibroblastic tumor (IMT), clear cell sarcoma (CCS), inflammatory fibroid polyp (IFP), and synovial sarcoma (SS). Molecular pathology is fast becoming a mainstream focus in laboratories because it aids in the precise classification of tumors, may be prognostic, and may help predict response to therapy. The following review is not intended as an exhaustive summary of all mesenchymal tumors that have been reported to involve the GI tract, but instead will highlight the current knowledge of the most important non-GIST GI mesenchymal neoplasms, focusing on those tumors with well-characterized molecular pathology and how the molecular pathologic features impact current diagnostic, therapeutic, and prognostic standards.

[Successful resection of locally advanced gastrointestinal stromal tumor of the ampulla of Vater after treatment with imatinib]

Gastrointestinal stromal tumor (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract arising from Cajal's cells, expressing CD 117. The standard treatment for primary GIST is complete surgical resection. Imatinib mesylate, a specific tyrosine kinase inhibitor, is effective against locally advanced and metastatic GIST. There are several reports of the effect of preoperative imatinib in patients with unresectable and locally advanced primary GIST. We report a case of unresectable primary GIST of the ampulla of Vater, which we were able to completely resect after treatment with a dosage of imatinib 400 mg daily for 5 months. Twelve months later, the patient was treated with imatinib and doing well with no evidence of recurrence.

Canine gastrointestinal stromal tumors: immunohistochemical expression of CD34 and examination of prognostic indicators including proliferation markers Ki67 and AgNOR

Gastrointestinal stromal tumors (GISTs), leiomyomas, and leiomyosarcomas are common mesenchymal neoplasms in the gastrointestinal (GI) tract of dogs. As previously diagnosed smooth muscle tumors of the canine GI tract are increasingly reclassified as GISTs, it becomes important to identify additional criteria that may assist in the diagnosis of these neoplasms, provide prognostic information, and offer targets for therapy. Examination of cluster of differentiation (CD), molecule expression (such as KIT [CD117] and CD34) as well as gross, histologic, and immunohistochemical features (such as tumor size, tumor location, mitotic index, AgNOR, and Ki67 labeling) in human GISTs has revealed new and valuable prognostic, diagnostic, and therapeutic information. In this study, GISTs were examined for the gross, histologic, and immunohistochemical features listed above. Forty-nine cases of canine gastrointestinal mesenchymal neoplasms from the Animal Medical Center (New York, NY) were categorized as GISTs (KIT positive), leiomyosarcoma/leiomyoma (KIT negative, smooth muscle actin [SMA], and/or desmin positive), or other (KIT, SMA, and desmin negative). A proportion (55%) of canine cases previously diagnosed as smooth muscle tumors were reclassified as GISTs according to KIT immunoreactivity. Statistical correlations with survival data were not possible because of insufficient follow-up data. However, there was a significant difference between mitotic index, AgNOR, and Ki67 scores depending on the location of the tumor (small vs large intestine). This study represents the first time CD34 immunoreactivity has been demonstrated in canine GISTs.

Colorectal gastrointestinal stromal tumors: a brief review

Gastrointestinal stromal tumors (GISTs) are rare lesions that constitute the majority of mesenchymal tumors in the gastrointestinal tract. Within the colon and rectum, they represent 0.1% of all cancers. They can present with a variety of symptoms but are often asymptomatic. Although many lesions may be benign, up to half of patients develop recurrent disease within a few years. Almost all GISTs contain a mutation in the c-kit tyrosine kinase that leads to its constitutive activation and results in cell proliferation. This discovery has led to the immunostaining of the c-kit antigen (CD117) to distinguish GISTs from other malignancies. Radiologic examinations can be helpful in initial diagnosis and staging. Surgery is the best treatment for cure, but recent advances have led to the use of imatinib mesylate, a tyrosine kinase inhibitor, to treat metastatic or unresectable disease, or both. There are currently many clinical trials available to help treat GISTs.

Gastrointestinal Stromal Tumors: A Guide to the Diagnosis

Gastrointestinal stromal tumors (GISTs) have emerged from being a poorly understood and therapeutically refractory sarcoma to a tumor whose biology has not only provided insight into a mechanism of oncogenesis but has also led to a rational basis for therapy. Most GISTs are characterized by KIT protein (CD117) expression and constitutive activating mutations in either the c-kit or platelet-derived growth factor receptor α genes. This information can now be obtained from routine formalin-fixed and paraffin-embedded tissue. Because the correct diagnosis is the key to successful treatment of this tumor, it is incumbent on the pathologist to be familiar with the various gross and histologic patterns shown by these tumors. GISTs range from small incidental stromal nodules to large cystic and solid tumor masses. GISTs show a variety of microscopic patterns and therefore several other tumors enter the differential diagnosis. Fortunately, with an understanding of GIST histology, and with the proper use of immunohistochemistry and molecular analysis, a correct diagnosis can usually be made. In addition to the correct diagnosis, several key attributes of the tumor need to be determined because they provide the basis for proper clinical management. This article summarizes the gross, microscopic, and molecular findings of GISTs, and discusses the differential diagnosis and key attributes of this interesting group of neoplasms.

Gastrointestinal stromal tumors: a review of the literature

Gastrointestinal stromal tumors are mesenchymal neoplasms with a spectrum of histologic appearances and biologic activity. The morphologic classification of these lesions has evolved over time, and molecular analysis has led to a better understanding of their nature. The histologic differential diagnosis for these lesions is broad and includes many spindle cell lesions of the gastrointestinal tract, including neoplasms of true smooth muscle and neural origin, proliferating fibrous lesions, metastatic neoplasms, and primary sarcomas of vascular and adipose origin. Immunohistochemical studies that include CD117 have become invaluable in the classification of mesenchymal lesions arising in the gastrointestinal tract. Treatment of gastrointestinal stromal tumors has historically been involved surgery, but the use of the chemotherapeutic agent imatinib mesylate for advanced disease has made accurate classification even more important. The molecular features have not only allowed us to understand the pathogenesis of these tumors but also have proven to be associated with response to kinase inhibitors.

Benign fibroblastic polyps of the colon

Benign fibroblastic polyps of the colon are a recently described entity among mucosal polyps found in the colorectum. These polyps are typically discovered on routine screening colonoscopy within the distal colon. Benign fibroblastic polyps occur most commonly in adult women in the sixth decade of life. Histologically, benign fibroblastic polyps are bland spindle cell lesions that fill the lamina propria and displace the surrounding crypts. The spindle cell proliferation lacks atypia and significant mitotic activity. Hyperplastic changes are frequently present both in the adjacent epithelium and within the lesions. Immunohistochemically, the cells of benign fibroblastic polyps are invariably positive for vimentin with rare focal positivity for CD34 and smooth muscle actin. They are negative for CD117 and S100 protein. Ultrastructurally, benign fibroblastic polyps have features of fibroblastic differentiation. These polyps are benign with no reports, to our knowledge, of recurrence or metastasis.

Best practices in diagnostic immunohistochemistry: spindle cell neoplasms of the gastrointestinal tract

CONTEXT

The proper classification of spindle cell neoplasms of the gastrointestinal tract frequently requires the use of immunohistochemistry, as the histologic appearance of these lesions often overlaps.

OBJECTIVE

To review the antibodies used in the diagnosis of spindle cell neoplasms of the gastrointestinal tract, and to outline an approach to the evaluation of these lesions by using immunohistochemistry.

DATA SOURCES

The authors' experience and a review of the English literature from 1976 to 2008.

CONCLUSIONS

The most common spindle cell neoplasm of the gastrointestinal tract is gastrointestinal stromal tumor; this lesion is readily diagnosed with c-kit immunohistochemistry in most cases. Other stains, such as smooth muscle actin, desmin, S100 protein, and beta-catenin, are also useful in the diagnosis of smooth muscle tumors, schwannomas, desmoid-type fibromatoses, and metastatic melanoma.

Role of EUS and MDCT in the diagnosis of gastric submucosal tumors according to the revised pathologic concept of gastrointestinal stromal tumors

Gastric submucosal tumors (SMTs) consist of various lesions arising from the deep layers of the stomach. Gastrointestinal stromal tumors (GISTs) are undoubtedly the commonest malignant SMTs of the stomach, and therefore the attitude towards the general diagnostic approach for GISTs defines the extended diagnostic plan for SMTs. Two recent consensus meetings were assembled concerning the classification and therapeutic plans for GISTs. These meetings shed light upon the need for the modification of the current role of imaging modalities, including endoscopic ultrasound (EUS) and computed tomography (CT). According to the revised concepts of GISTs, the most important and plausible current role of imaging for the diagnostic approach of gastric SMTs is to differentiate GISTs from other gastric SMTs. This review discusses the newly established diagnostic role of radiology according to the revised classification of GISTs and provides the differential diagnoses based on EUS and CT findings.

Endosonographic features of gastric ectopic pancreases distinguishable from mesenchymal tumors

BACKGROUND AND AIMS

Gastric ectopic pancreas is the second common submucosal lesion in the stomach, and differs from mesenchymal tumors with respect to clinical approach and prognosis. The purpose of our study was to evaluate the endoscopic ultrasound (EUS) findings for differentiating between gastric ectopic pancreases and mesenchymal tumors.

METHODS

All patients (n = 71) were diagnosed pathologically as having gastric ectopic pancreas (n = 18) or mesenchymal tumors (n = 53) between 2002 and 2006. The EUS images of the patients were retrospectively reviewed by two observers who were unaware of the pathological results, regarding location, size, growth pattern, layer of origin, presence or absence of layer disruption, margin, and internal echo pattern. These EUS imaging findings were compared for ectopic pancreases and mesenchymal tumors.

RESULTS

Compared with mesenchymal tumors, ectopic pancreases showed a significant difference in the lesion location, growth pattern, layer of origin, presence of layer disruption, margin, and internal echo (P < 0.05). The longest/shortest diameter ratio was also larger in ectopic pancreases (p < 0.05). There was no statistical difference in the lesion size and presence of focal anechoic portion.

CONCLUSION

Careful assessment of the EUS findings may be a useful aid in the differentiation of ectopic pancreases from mesenchymal tumors in the stomach.