Gastrointestinal stromal tumors: radiologic features with pathologic correlation

Giant gastric gastrointestinal stromal tumor: A case report

INTRODUCTION AND IMPORTANCE

Gastrointestinal stromal tumor is the most common mesenchymal tumor of the digestive tract. With occurrence in <5 % of all gastrointestinal tract tumors, they encompass 60 % of all gastric stromal tumors.

CASE PRESENTATION

A 60-year-old man presented to the emergency department with pain abdomen and lump for the past 4 months. Contrast enhanced computed tomography (CECT) abdomen showed a large (largest dimension-25 cm), well-defined, soft tissue lesion on left side of abdominal cavity, crossing the midline to the right side. En-bloc tumor resection with wedge resection of the gastric body was performed. On histopathological examination, definitive diagnosis of giant gastric gastrointestinal stromal tumor (GIST) was established. Postoperatively, the patient received adjuvant oral Imatinib therapy, and is recurrence free at 3-years of follow-up.

CLINICAL DISCUSSION

The clinical manifestations of GIST are non-specific and vary from being asymptomatic to several signs and symptoms such as abdominal pain, a palpable mass, bleeding, intestinal occlusion, and perforation. Surgical resection is the treatment of choice for GISTs, and neoadjuvant imatinib mesylate therapy for locally advanced GISTs confers good prognosis.

CONCLUSIONS

Despite the fact that luminal bleeding is the most common presentation, sometimes the tumor may grow exophytically without any symptoms. If large enough as observed in the present case, they may present to emergency department as intra-tumoral bleed. Surgical resection and neoadjuvant therapy with imatinib is equally advantageous even for giant GIST. Diagnosis and therapeutical protocol of GISTs should be established by a trans-disciplinary team.

Lessons Learned in Emergency Pelvic and First-Trimester US: Focus on Cognitive Biases

Nonpregnant and pregnant women who present with acute pelvic pain can pose a diagnostic challenge in the emergency setting. The clinical presentation is often nonspecific, and the differential diagnosis may be very broad. These symptoms are often indications for pelvic US, which is the primary imaging modality when an obstetric or gynecologic cause is suspected. Interpretation of pelvic US may be challenging and a source of confusion and misinterpretation for radiologists. Additionally, cognitive biases in imaging interpretation can contribute to diagnostic errors. Cognitive biases represent systematic errors due to failure of the mental shortcuts that the brain subconsciously uses to produce quicker judgments. There are multiple different types of cognitive biases, all of which may lead to perceptual and interpretive errors. Familiarity with common and uncommon pelvic US findings in the setting of pelvic pain is imperative to assist with prompt and accurate diagnosis. Awareness of potential biases when interpreting pelvic US findings further helps hone the interpretation. The authors illustrate the imaging findings in several peer learning cases of nonpregnant and first-trimester pregnant patients who presented with acute pelvic pain in the emergency setting. Several nonobstetric and nongynecologic causes of acute pelvic pain are included for which pelvic US was the first imaging modality used in diagnosis. Diagnostic errors and cognitive biases in interpretation related to these cases are highlighted. The radiologist's awareness of potential cognitive biases in image interpretation may help to refine the differential diagnosis and mitigate errors. ©RSNA, 2025 Supplemental material is available for this article.

Characterization of the epidemiologic, pathologic, radiologic, and management profile of patients with gastrointestinal stromal tumors (GISTs): A 5-year Chilean experience

INTRODUCTION AND AIMS

Gastrointestinal stromal tumors (GISTs) are the most frequent mesenchymal neoplastic tumors of the gastrointestinal tract and their expression and management is dependent on their aggressivity. Our aim was to characterize the GISTs diagnosed at our center, analyzing the epidemiologic, anatomopathologic, imaging study, and management variables.

MATERIAL AND METHODS

A retrospective, observational cohort study was conducted on adult patients diagnosed with GIST through imaging studies and biopsy, within the time frame of 2017 and 2022 at our center, characterizing the epidemiologic, imaging study, anatomopathologic, and therapeutic data.

RESULTS

Thirty-three patients with a mean age of 59 years were included. The majority of cases were incidental findings (54.5%), and of the symptomatic cases, the most frequent presentation was gastrointestinal bleeding (24%). The most common location was the stomach (19/33 cases), and the most frequent presentation was exophytic (48.5%). In the imaging studies, impregnation was mainly heterogeneous and progressive and 54% had an intrinsic characteristic, with necrosis/cystic areas the most frequent feature. There were no cases of local invasion or distant metastasis. Histologically, the spindle cell type was the most frequent (78.8%) and the majority had fewer than 5 mitoses per high power field. Thirty cases were treated at our center and surgery was the most frequent form of resolution (29/30). No deaths caused by GIST were registered in our case series.

CONCLUSIONS

The epidemiologic and imaging study characteristics in our case series were similar to those reported in the literature, but our results were different, with respect to early diagnosis and the low aggressivity of the cases.

Identifying subtle differences : a radiomics model assessment for gastric schwannomas and gastrointestinal stromal tumors across risk grades

Objective

This study aims to develop and validate an enhanced computed tomography (CT)-based radiomics model to differentiate gastric schwannomas (GS) from gastrointestinal stromal tumors (GIST) across various risk categories.

Methods

This retrospective analysis was conducted on 26 GS and 82 GIST cases, all confirmed by postoperative pathology. Data was divided into training and validation cohorts at a 7:3 ratio. We collected patient demographics, clinical presentations, and detailed CT imaging characteristics. Through univariable and multivariable logistic regression analyses, we identified independent predictors for discriminating between GS and GIST, facilitating the construction of a conventional model. Radiomic features were extracted and refined through manual 3D segmentation of venous phase thin-slice images to develop a radiomics model. Subsequently, we constructed a comprehensive combined model by integrating selected clinical and radiomics indicators. The diagnostic performances of all models in differentiating GS from GIST and stratifying GISTs according to malignancy risk were evaluated.

Results

We identified several key independent variables distinguishing GS from GIST, including tumor location, cystic changes, degree of enhancement in arterial phase, and enhancement uniformity. The conventional model achieved AUCs of 0.939 and 0.869 in the training and validation cohort, respectively. Conversely, the radiomics model, predicated on eight pivotal radiomics features, demonstrated AUCs of 0.949 and 0.839. The combined model, incorporating tumor location, degree of enhancement in arterial phase, enhancement uniformity, and a radiomics model derived rad-score, significantly outperformed the traditional approach, achieving AUCs of 0.989 and 0.964 in the respective cohorts. The combined model showed superior diagnostic accuracy in distinguishing GS from GIST, as well as GS from high or low malignancy potential GISTs, as evidenced by IDI values of 0.2538, 0.2418, and 0.2749 (P<0.05 for all).

Conclusion

The combined model based on CT imaging features and radiomics features presents a promising non-invasive approach for accurate preoperative differentiation between gastric schwannomas and gastrointestinal stromal tumors.

Findings of Endoscopic US and CT of Esophageal Disease

Various diseases can affect the esophagus. Endoscopic ultrasound (EUS), which provides precise information about the layers of the esophageal wall, is the primary approach used to investigate esophageal diseases. However, CT is one of the most important imaging modalities for diagnosing esophageal diseases as it can elucidate mediastinal involvement, adjacent lymphadenopathy, and distant disease spread. These two modalities complement each other in the diagnosis of esophageal diseases. Although radiologists may be unfamiliar with EUS procedures and their interpretation, understanding them aids in the differential diagnosis of esophageal conditions. This pictorial essay illustrates the EUS and CT findings of various esophageal diseases originating in the esophageal wall.

Gastrointestinal Stromal Tumors (GISTs) Mimicking Primary Ovarian Tumors or Metastasizing to the Ovaries: A Systematic Literature Review

Background: Gastrointestinal stromal tumors (GISTs) are a rare neoplasm, sometimes mimicking primary ovarian tumors (OTs) and/or metastasizing to the ovaries (M-OT). We performed a systematic literature review (SLR) of OTs and M-OTs, investigating differences in recurrence-free and overall survival. Methods: Our SLR was performed according to PRISMA guidelines, searching in Pubmed, Scopus, and Web of Science databases from inception until 21 April 2024. Results: Overall, 59 OTs (Group 1) and 21 M-OTs (Group 2) were retrieved. The absence of residual disease after surgery was achieved significantly in a higher percentage of patients with Group 1 GISTs (91.5%) compared with Group 2 GISTs (57.1%). Chemotherapy was more frequently administered to Group 2 patients (33% vs. 0%). Recurrence and deaths for disease were significantly more frequent in Group 2 than Group 1 cases (54.5% vs. 6.8%, and 37.5% vs. 9.8%, respectively). Conclusions: GISTs can rarely mimic primary ovarian cancers or even more rarely metastasize to the ovaries. Group 1 GISTs occurred in younger women, were not associated with elevated tumor markers, and had a better prognosis. In contrast, Group 2 GISTs occurred in older women, may exhibit elevated tumor markers, and presented a worse prognosis. However, no significant statistical difference for survival between the two studied groups was detected. Computed tomography scans can define the size of GISTs, which correlate to stage and prognostic risk classes. The gold standard treatment is complete surgical resection, which was achieved in almost all cases of Group 1 GISTs and in half of Group 2. Histopathology and immunohistochemistry are essential for the final diagnosis and guide chemotherapy treatment.

Cinematic Rendering of Gastrointestinal Stromal Tumours: A Review of Current Possibilities and Future Developments

Gastrointestinal stromal tumours (GISTs) are defined as CD117-positive primary, spindled or epithelioid, mesenchymal tumours of the gastrointestinal tract, omentum, or mesentery. While computed tomography (CT) is the recommended imaging modality for GISTs, overlap in imaging features between GISTs and other gastrointestinal tumours often make radiological diagnosis and subsequent selection of the optimal therapeutic approach challenging. Cinematic rendering is a novel CT post-processing technique that generates highly photorealistic anatomic images based on a unique lighting model. The global lighting model produces high degrees of surface detail and shadowing effects that generate depth in the final three-dimensional display. Early studies have shown that cinematic rendering produces high-quality images with enhanced detail by comparison with other three-dimensional visualization techniques. Cinematic rendering shows promise in improving the visualization of enhancement patterns and internal architecture of abdominal lesions, local tumour extension, and global disease burden, which may be helpful for lesion characterization and pretreatment planning. This article discusses and illustrates the application of cinematic rendering in the evaluation of GISTs and the unique benefit of using cinematic rendering in the workup of GIST with a specific emphasis on tumour characterization and preoperative planning.

Advanced and Metastatic Gastrointestinal Stromal Tumors Presenting With Surgical Emergencies Managed With Surgical Resection: A Case Series

Advanced and metastatic gastrointestinal stromal tumors (GISTs) presenting with surgical emergencies are rare. Neoadjuvant imatinib being the treatment of choice for non-metastatic advanced disease with a proven role in downstaging the disease may not be feasible in patients presenting with bleeding and obstruction. We present a case series with retrospective analysis of a prospectively maintained database of patients with advanced and metastatic GISTs presenting with surgical emergencies. Clinical characteristics, imaging and endoscopic findings, surgical procedures, histological findings, and outcomes in these patients were studied. Four patients were included in this case series, with three males and one female (age range: 24-60 years). Two patients presented with melena; one with hemodynamic instability despite multiple blood transfusions underwent urgent exploratory laparotomy for bleeding gastric GIST, while the other underwent surgical exploration after careful evaluation given the recurrent, metastatic disease with a stable metabolic response on six months of imatinib. One patient with metastatic jejunal GIST who presented with an umbilical nodule and intestinal obstruction was given a trial of non-operative management for 72 hours, but due to non-resolution of obstruction, segmental jejunal en bloc resection with the dome of the urinary bladder with reconstruction and metastasectomy was needed. The patient with advanced gastric GIST who presented with gastric outlet obstruction was resuscitated, and an attempt of endoscopic naso-jejunal tube placement was tried, which failed, and exploration was needed. The mean length of hospital stay was 7.5 days. Histopathological examination confirmed GIST in all four patients with microscopic negative resection margins. All patients were started on imatinib with dose escalation to 800 mg in the patient with recurrent and metastatic disease; however, the patient with bleeding gastric GIST experienced severe adverse effects of imatinib and discontinued the drug shortly. All four patients are disease-free on follow-ups of 15 months, 48 months for the patient with advanced non-metastatic disease, and six and 24 months for the patients with metastatic disease. In the era of tyrosine kinase inhibitor (TKI) therapy for advanced and metastatic disease, upfront surgery is usually reserved for surgical emergencies only. Surgical resection, the cornerstone for the treatment of resectable GIST, may also be clinically relevant in metastatic settings, although it requires a careful and individualized approach.

CT and MRI of Gastrointestinal Stromal Tumors: New Trends and Perspectives

Gastrointestinal stromal tumors (GISTs) are defined as mesenchymal tumors of the gastrointestinal tract that express positivity for CD117, which is a c-KIT proto-oncogene antigen. Expression of the c-KIT protein, a tyrosine kinase growth factor receptor, allows the distinction between GISTs and other mesenchymal tumors such as leiomyoma, leiomyosarcoma, schwannoma and neurofibroma. GISTs can develop anywhere in the gastrointestinal tract, as well as in the mesentery and omentum. Over the years, the management of GISTs has improved due to a better knowledge of their behaviors and risk or recurrence, the identification of specific mutations and the use of targeted therapies. This has resulted in a better prognosis for patients with GISTs. In parallel, imaging of GISTs has been revolutionized by tremendous progress in the field of detection, characterization, survival prediction and monitoring during therapy. Recently, a particular attention has been given to radiomics for the characterization of GISTs using analysis of quantitative imaging features. In addition, radiomics has currently many applications that are developed in conjunction with artificial intelligence with the aim of better characterizing GISTs and providing a more precise assessment of tumor burden. This article sums up recent advances in computed tomography and magnetic resonance imaging of GISTs in the field of image/data acquisition, tumor detection, tumor characterization, treatment response evaluation, and preoperative planning.

Comparing endoscopic ultrasonography and double contrast-enhanced ultrasonography in the preoperative diagnosis of gastric stromal tumor

BACKGROUND

This study was designed to perform a comparative analysis between endoscopic ultrasonography (EUS) and double contrast-enhanced ultrasonography (DCEUS) for the preoperative diagnosis of gastric stromal tumors (GSTs).

METHODS

A retrospective study was conducted involving 139 patients with histologically confirmed GSTs. All patients preoperatively underwent DCEUS and EUS. The pathology reports were treated as the baseline and were retrospectively compared with the findings of EUS and DCEUS.

RESULTS

Of the 139 lesions, 120 and 113 were correctly identified by DCEUS and EUS, respectively, with an accuracy of 86.3% and 81.3%. The results revealed an insignificant difference between these two methods (p = 0.189).

CONCLUSIONS

DCEUS can display not only the locations, sizes, shapes, borders, internal echoes, but also show the blood perfusion patterns of GSTs. It is a highly accurate, noninvasive, and convenient method to be used at the pre-treatment stage.

Clinical significance of dual-energy dual-layer CT parameters in differentiating small-sized gastrointestinal stromal tumors from leiomyomas

PURPOSE

Small gastrointestinal stromal tumors (GISTs) can generally have nonspecific CT findings similar to those with benign submucosal tumors of the stomach. The purpose of this study was to explore the potential dual-layer dual-energy CT (dlDECT) parameters to differentiate small-sized (≤ 4 cm) GISTs from leiomyomas of the stomach.

MATERIALS AND METHODS

This retrospective study included 26 SMTs ≤ 4 cm in diameter with pathological confirmation of either GIST (n = 17) or leiomyoma (n = 9) from May 2018 to January 2022. All patients received contrast-enhanced CT. The normalized iodine concentration (NIC) and spectral slope (λHU) were compared between GIST and leiomyoma. Receiver-operating characteristic (ROC) curves were plotted and the areas under the curve (AUCs) were calculated to estimate the diagnostic performance of these markers for differentiating GISTs from leiomyomas.

RESULTS

NIC was significantly higher in GIST than in leiomyoma in the portal (P = 0.0019) and delayed phases (P = 0.0011). λHU was significantly higher in GIST than in leiomyoma in the portal (P = 0.0006) and delayed phases (P = 0.0009). AUC of the ROC curves using NIC to differentiate between GIST and leiomyoma were 0.875 and 0.895 in the portal and delayed phase; using λHU, they were 0.918 and 0.902 in the portal and delayed phase.

CONCLUSION

dlDECT parameters including NIC and λHU show promise as indicators for differentiating small-sized GISTs from leiomyomas.

A case of primary gastrointestinal stromal tumor of the liver

A gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract. The tumor originates from Cajal cells, which generated peristaltic motion. Primary gastrointestinal stromal tumor of the liver is rare and should be considered in imaging diagnosis. We report a case of an 82-year-old female patient who represented with upper abdominal pain and poor appetite. Magnetic resonance imaging detected a large left lobe cystic lesion (10 × 15 cm). The tumor was resected. The histopathological and immunohistochemical results were of a primary gastrointestinal stromal tumor in the liver with cystic changes. On imaging, it is difficult to differentiate from other cystic lesions.

Anorectal Gastrointestinal Stromal Tumor: Report of a Rare Case

Gastrointestinal stromal tumors (GIST) are mesenchymal spindle cell tumors of the gastrointestinal tract with the rarest occurrence in anal canal sites accounting for approximately only 2-8% of the anorectal GISTs. GISTs involve the expression of KIT (CD117) tyrosine kinase with the presence of mutations in KIT or platelet-derived growth factor alpha (PDGFRα) and are identified as an important target in therapy. The elderly population in the age of 70s appears to be at the highest risk with abdominal pain, GI bleeding, anemia, or weight loss as non-specific presenting symptoms. Here, we describe a case of a 56-year-old man who presented with vague dull pain in his left buttock diagnosed with GIST with a submucosal mass in the posterior wall of the anal canal and rectum and a tumor size of 45x42x37 mm. An immunohistological study of the biopsy sample reported positive for CD 117, CD 34, and DOG 1. The patient was prescribed neoadjuvant imatinib for 8 months with a good response and subsequently underwent transanal endoscopic microsurgical resection. Post-operatively, the patient was continued on adjuvant imatinib followed by regular restaging CT chest/abdomen/pelvis and surveillance flexible sigmoidoscopy every 6 months.

Gastric ectopic pancreas in magnetic resonance imaging: A review of 2 cases

Gastric ectopic pancreas (EP) is an uncommon congenital anomaly in which pancreatic tissue with no anatomic connection to the main pancreas is found in the stomach. Gastric EP is often discovered incidentally when a nonspecific submucosal tumor is found in endoscopic studies or other imaging examinations. Tissue characterization by biopsy or fine-needle aspiration is required as endoscopic findings alone cannot exclude malignancy. The authors present 2 cases of gastric EP incidentally detected on endoscopy, which underwent further characterization by magnetic resonance imaging (MRI). In both cases, MRI showed submucosal gastric lesions, isointense to the orthotopic pancreas in all sequences, including hyperintensity on T1-weighted images. Furthermore, the lesions showed bright arterial phase enhancement, paralleling the native pancreas. MRI may provide the best non-invasive imaging method for evaluating gastric submucosal lesions. This report intends to show that EP shows a characteristic MR appearance that allows differentiation from other submucosal lesions.

Radiological Evaluation of a Malignant Gastrointestinal Stromal Tumor in a Female Patient With the Coincidental Detection of Primary Breast Cancer: A Case Report

Gastrointestinal stromal tumors (GIST) are a rare and unique group of mesenchymal tumors arising from the gastrointestinal tract, omentum, mesentery, and retroperitoneum. Though they have certain typical radiological features that can differentiate them from epithelial tumors, it is often difficult to differentiate them from other non-epithelial tumors. Their features also vary depending on their size, site of origin, etc. When differentiation from other mesenchymal tumors on histopathology is difficult, receptor tyrosine kinase (C-KIT proto-oncogene/CD117) and gastrointestinal stromal tumor (GIST-1) discovered on GIST1 (DOG-1) expression are confirmatory. The concurrent presence of other primary cancers with GISTs has been described in the literature, among which most have been of gastrointestinal origin. Few cases of primary breast cancer in GIST have been described. Lymph nodal metastasis is rarely encountered in GIST, and metastasis to the breast is even rarer. We present a case of a 39-year-old female with non-specific symptoms who was referred for ultrasonography (USG) and computed tomography (CT) that showed a small intestinal GIST along with a breast lump and axillary lymphadenopathy that were labeled as metastases from the GIST on frozen sections; however, they were later diagnosed as primary breast cancer with axillary metastases on the histopathology and immunohistochemistry of the excision biopsy specimens post-surgery. The patient underwent surgical resection and chemotherapy.

Radiologic Review of Small Bowel Malignancies and Their Mimicking Lesions

Because of their small size, small bowel malignancies are often easily missed when radiologists read CT images, which can lead to errors in the normal small bowel due to their similar enhancement to the small bowel or non-specific enhancement. In addition, small bowel malignancies are sometimes mistaken for masses of other origins, such as the uterus, rectum, or omentum. In this article, we describe various small-bowel malignancies, their mimicking lesions and the typical and atypical features on CT imaging along with their clinical manifestations.

Gas-containing mesenteric desmoid-type fibromatosis: A case report

RATIONALE

Desmoid-type fibromatosis is a rare benign mesenchymal neoplasm. Only 8% of desmoid-type fibromatosis develops in the abdominal cavity. The mesentery is seldom affected and gastrointestinal stromal tumors need to be considered in the differential diagnosis, particularly when imaging examination shows a tumor containing gases in the abdominal cavity. Only a few cases of gas-containing mesenteric desmoid-type fibromatosis have been reported in the literature.

PATIENT CONCERNS

A 69-year-old male patient presented with hematochezia and intermittent upper abdominal pain.

DIAGNOSIS

Contrast-enhanced computed tomography revealed a 3.9 × 3.6 cm gas-containing mass infiltrating the third portion of the duodenum. The tumor was heterogeneous, with cysts and air bubbles. It showed heterogeneous weak-to-mild enhancement in the solid part. Postoperative pathological examination confirmed a final diagnosis of mesenteric desmoid-type fibromatosis.

INTERVENTIONS

The patient underwent surgical resection of intra-abdominal lesion.

OUTCOMES

No evidence of local recurrence was noted during the 6 months of follow-up.

LESSONS

Accurate preoperative diagnosis is difficult for an intra-abdominal gas-containing mass on computed tomography scan. The appearance of spiculated infiltrative margin suggests the diagnosis of desmoid-type fibromatosis. Further investigation of imaging evidence and treatment methods is necessary.

A Gastroenterologist's Approach to the Diagnosis and Management of Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal (GI) tract. These tumors have been shown to harbor oncogenic mutations of the c-kit tyrosine kinase receptor or platelet-derived growth factor receptor alpha (PDGFRA). Immunohistochemical analysis of GISTs allows for the differentiation of these tumors from other mesenchymal tumors of the GI tract such as leiomyomas and leiomyosarcomas. All GISTs have the potential to behave in a malignant fashion. Tumor location, size, and mitotic index are factors used to predict the risk of malignant behavior. Endoscopy and endoscopic ultrasound play a critical role in the diagnosis of GISTs and can yield important information to further risk-stratify tumors and determine management. This article provides a gastroenterologist's perspective on the diagnosis and management of GISTs.

Ewing sarcoma of the ileum with wide multiorgan metastases: A case report and review of literature

BACKGROUND

Ewing sarcoma (ES) is an aggressive small round cell tumor that usually occurs in younger children and young adults but rarely in older patients. Its occurrence in elderly individuals is rare. ES of the ileum with wide multiorgan metastases is rarely reported and difficult to distinguish radiologically from other gastrointestinal tract tumors.

CASE SUMMARY

A 53-year-old man presented with right lower quadrant pain for 2 wk. Computed tomography results showed a heterogeneous mass within the ileum and widespread multiorgan metastases. This mass was biopsied, and pathological examination of the resected specimen revealed features consistent with an extraskeletal ES.

CONCLUSION

This case emphasizes the importance of recognizing this rare presentation in the small intestine to broaden the differential diagnosis of adult intraabdominal tumors.

Confirmation of Ectopic Pancreatic Tissue: A Novel Use for 18 F-Fluciclovine PET

ABSTRACT

This case features a 21-year-old woman with a history of ulcerative colitis who was incidentally found to have a para-jejunal mass when she presented with an ulcerative colitis flare. The mass was further characterized on MR enterography as most likely representing ectopic pancreatic tissue. Given the normal intense pancreatic uptake of 18 F-fluciclovine, PET/CT was subsequently used to confirm that the mass represented ectopic pancreatic tissue.

A para-aortic malignant melanotic nerve sheath tumor mimicking a gastrointestinal stromal tumor: a rare case report and review of literature

Background

Malignant melanotic nerve sheath tumor (MMNST), formerly called melanotic schwannoma, is a rare tumor of neural crest derivation which most frequently arises from the region of spinal or autonomic nerves near the midline. Recent studies have reported malignant behavior of MMNST, and there still has no standard management guidelines. Intra-abdominal MMNST, which has never been reviewed as an entity, is even rarer. In this study, we present a rare case of a cystic MMNST arising from the para-aortic region and mimicking an intra-abdominal gastrointestinal stromal tumor (GIST), and review the literature regarding MMNSTs located in the abdominal cavity.

Case presentation

A 59-year-old female was incidentally found a tumor located in the left para-aortic area by non-contrast computed tomography. A Magnetic Resonance Imaging showed a cystic mass originated from the inferior mesenteric artery (IMA) territory. A GIST was initially diagnosed. The tumor was resected en bloc by laparoscopic surgery and was found between mesocolon and Gerota’s fascia with blood supply of IMA. Grossly, dark brown materials were noted at the inner surface of the cystic wall. Microscopically, the tumor cells were melanin-containing, and no psammomatous bodies were present. Immunohistochemically, the tumor showed positivity for MART1, HMB45, collagen IV, and SOX10, and negativity for AE1/AE3. MMNST was favored over malignant melanoma, since the tumor was located near ganglia and had cells with less atypical cytology and a low mitotic rate, and subsequent adjuvant radiotherapy was performed. The patient was alive with no evidence of recurrent or metastatic disease 11 months after radiotherapy.

Conclusions

Our review of abdominal MMNST cases showed a female predominance, with an average age of 54.8 years, and a trend toward being a larger tumor showing cystic or necrotic changes. Local recurrence and metastasis rate were reviewed, and both showed a low rate. Diagnosis of MMNST should combine all the available findings, and complete excision of the tumor should be performed, followed by long-term patient monitoring.

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.

Gastrointestinal bleeding: imaging and interventions in cancer patients

Gastrointestinal bleeding (GIB) among cancer patients is a major source of morbidity and mortality. Although a wide variety of etiologies contribute to GIB, special considerations should be made for cancer-related factors such as the type of malignancy, location and extent of disease, hemostatic parameters, and treatment effects. Key imaging modalities used to evaluate GIB include computed tomography angiography (CTA), radionuclide imaging, and catheter-based angiography. Understanding the cancer and treatment history and recognizing the associated imaging manifestations are important for identifying the source and potential causes of GIB in cancer patients. This article will review the common clinical presentations, causes, imaging manifestations, and angiographic management of GIB in cancer patients.

Correlation between pneumo-computed tomography and pathology findings for subepithelial gastric lesions

OBJECTIVE

This article aims to show the usefulness of the pneumo-computed tomography gastric distention technique in the detection and morphological characterization of subepithelial gastric lesions. We correlate the pneumo-computed tomography and pathology findings in lesions studied at our institution and review the relevant literature.

CONCLUSION

Pneumo-computed tomography, combined with multiplanar reconstructions, three-dimensional reconstructions, and virtual endoscopy, is useful for delineating the morphological details of subepithelial gastric lesions, thanks to the additional gastric distention. This technique better delimits and characterizes the upper and lower margins of the lesions. Pneumo-computed tomography can be considered a useful noninvasive imaging techniques for characterizing these lesions.

Mesenchymal Neoplasms of the Prostate and Seminal Vesicles: Spectrum of Disease with Radiologic-Pathologic Correlation

There is a wide spectrum of benign and malignant mesenchymal neoplasms of the prostate, which account for less than 1% of all prostatic tumors. These include distinctive tumors that arise from the specialized prostatic stroma and site-agnostic neoplasms such as smooth muscle tumors, fibrous or myofibroblastic neoplasms, neurogenic tumors, vascular tumors, and a plethora of sarcomas. Select tumors show classic sites of origin within the prostate. While stromal tumors of uncertain malignant potential (STUMPs) commonly involve the peripheral zone at the prostate base, leiomyomas typically originate from the central prostate toward the apex. Some "prostatic" neoplasms such as gastrointestinal stromal tumors, solitary fibrous tumor (SFT), paragangliomas, and neurogenic tumors arise primarily from periprostatic soft tissues. Most mesenchymal tumors of the prostate and seminal vesicles manifest as large tumors that cause nonspecific symptoms; prostate-specific antigen level is not typically elevated. Diverse mesenchymal neoplasms demonstrate characteristic histopathologic and immunocytochemical features and variable cross-sectional imaging findings. While leiomyoma and SFT typically display low signal intensity on T2-weighted images, synovial sarcomas commonly show hemorrhage. Diagnosis is difficult because of the rarity and lack of awareness of the tumors and the significant overlap in histopathologic features. Select tumors show characteristic genetic abnormalities that allow the diagnosis to be established. For example, more than 90% of SFTs are characterized by a unique NAB2-STAT6 gene fusion, and more than 95% of synovial sarcomas are associated with a distinctive SYT-SSX chimeric transcript. Accurate diagnosis is imperative for optimal management owing to markedly different tumor biology as well as attendant therapeutic and prognostic implications. While STUMPs commonly recur, sarcomas typically charter an aggressive course with poor prognosis. Online supplemental material is available for this article. ^©RSNA, 2022.

Insight into gastrointestinal heterotopic pancreas: imaging evaluation and differential diagnosis

Heterotopic pancreas (HP) is an uncommon congenital abnormality in the developmental process of the pancreas, with gastrointestinal heterotopic pancreas (GHP) being the most common HP. The clinical manifestations of GHP may have variable patterns of presentation, dictated by both the anatomic location and the functional ability of the lesion. The most common imaging modality in detecting GHP is computed tomography (CT), while gastrointestinal barium fluoroscopy, endoscopic ultrasonography, and magnetic resonance imaging (MRI) are also applied. The density and enhancement patterns of GHP are consistent with histological classifications. GHP with a predominantly acinar tissue component manifests homogeneous and marked enhancement on CT images, whereas a predominantly ductal GHP presents heterogeneous and mild enhancement. On MRI, the appearance and signal intensity of GHP were paralleled to the normal pancreas on all sequences and were characterized by T1-weighted high signal and early marked enhancement. This article provides a comprehensive review of the histopathology, clinical manifestations, imaging features of various modalities, and differential diagnosis of GHP. It is hoped that this review will improve clinicians' knowledge of GHP and aid in accurate preoperative diagnosis, thereby reducing the misdiagnosis rate.

Approach to Cystic Lesions in the Abdomen and Pelvis, with Radiologic-Pathologic Correlation

Cystic lesions found in and around the peritoneal cavity can often be challenging to diagnose owing to significant overlap in imaging appearance between the different entities. When the cystic lesion can be recognized to arise from one of the solid abdominal organs, the differential considerations can be more straightforward; however, many cystic lesions, particularly when large, cannot be clearly associated with one of the solid organs. Cystic lesions arising from the mesentery and peritoneum are less commonly encountered and can be caused by relatively rare entities or by a variant appearance of less-rare entities. The authors provide an overview of the classification of cystic and cystic-appearing lesions and the basic imaging principles in evaluating them, followed by a summary of the clinical, radiologic, and pathologic features of various cystic and cystic-appearing lesions found in and around the peritoneal cavity, organized by site of origin. Emphasis is given to lesions arising from the mesentery, peritoneum, or gastrointestinal tract. Cystic lesions arising from the liver, spleen, gallbladder, pancreas, urachus, adnexa, or soft tissue are briefly discussed and illustrated with cases to demonstrate the overlap in imaging appearance with mesenteric and peritoneal cystic lesions. When approaching a cystic lesion, the key imaging features to assess include cyst content, locularity, wall thickness, and presence of internal septa, solid components, calcifications, or any associated enhancement. While definitive diagnosis is not always possible with imaging, careful assessment of the imaging appearance, location, and relationship to adjacent structures can help narrow the differential diagnosis. Online supplemental material is available for this article. ^©RSNA, 2021.

A Case of Accidentally Found Gastrointestinal Stromal Tumor in a 57-Year-Old Candidate of Gastric Bypass Surgery

INTRODUCTION

GIST tumors are the most common mesenchymal tumors in the alimentary tract but are rather rare compared to other GI tract tumors and are usually found incidentally. Studies about cases of GIST tumor in bariatric surgery are scarce and there is no specific guideline for treatment. Most of previous cases were managed by sleeve gastrectomy due to their location which were usually in the body and greater curvature.

METHODS

This patient had a GIST on lesser curvature and therefore underwent laparoscopic Roux-en-Y bypass. The follow-up was done with imaging studies and CT scan since the location of the tumor was no longer accessible to endoscopy after the gastric bypass.

RESULTS

The post-operative course was uneventful and after 2 years the patient is still in good health and had no other complications. The patient has been followed up by imaging studies.

DISCUSSION

There are pros and cons to this compared with sleeve gastrectomy. The most important advantage for this approach is that we have the stomach preserved; thus, our operation has the reversibility potential in case of any complication which requires revision operations. However, on the flip side, the limitation of such intervention is that we are not able to use the EGD to monitor and follow up our patient. Based on the relevant literature, for following up and monitoring the postoperative condition of these patients with relatively small GISTs, imaging studies specially abdominal computed tomography scan (CT scan) would be highly beneficial. It is also worth of mentioning that performing a EGD before a bariatric surgery, which is well noted in IFSO position statements and is well explained and discussed in other literature, had a major role in diagnosing this patient's GIST tumor and is proved to be beneficial and essential, once again.

A case of KIT negative extra-gastrointestinal stromal tumor arising in the greater omentum with predominant cystic formation

We report a rare case of KIT-negative extra-gastrointestinal stromal tumor, in a 40-year-old woman. Contrast-enhanced computed tomography and magnetic resonance imaging revealed a >15-cm mass of multiple cystic lesions in the greater omentum. Histopathological findings after surgery showed a sheet-like growth of stellate tumor cells from epithelial cells, cystic degeneration, and mucus-like stroma. Immunohistochemistry was positive for discovered on GIST-1 (DOG1) but negative for CD117 (c-kit).

Differentiation of gastric schwannomas from gastrointestinal stromal tumors by CT using machine learning

OBJECTIVE

To identify schwannomas from gastrointestinal stromal tumors (GISTs) by CT features using Logistic Regression (LR), Decision Trees (DT), Random Forest (RF), and Gradient Boosting Decision Tree (GBDT).

METHODS

This study enrolled 49 patients with schwannomas and 139 with GISTs proven by pathology. CT features with P < 0.1 derived from univariate analysis were inputted to four models. Five machine learning (ML) versions, multivariate analysis, and radiologists' subjective diagnostic performance were compared to evaluate diagnosis performance of all the traditional and advanced methods.

RESULTS

The CT features with P < 0.1 were as follows: (1) CT attenuation value of unenhancement phase (CTU), (2) portal venous enhancement (CTV), (3) degree of enhancement in the portal venous phase (DEPP), (4) CT attenuation value of portal venous phase minus arterial phase (CTV-CTA), (5) enhanced potentiality (EP), (6) location, (7) contour, (8) growth pattern, (9) necrosis, (10) surface ulceration, (11) enlarged lymph node (LN). LR (M1), RF, DT, and GBDT models contained all of the above 11 variables, while LR (M2) was developed using six most predictive variables derived from (M1). LR (M2) model with AUC of 0.967 in test dataset was thought to be optimal model in differentiating the two tumors. Location in gastric body, exophytic and mixed growth pattern, lack of necrosis and surface ulceration, enlarged lymph nodes, and larger EP were the most important CT features suggestive of schwannomas.

CONCLUSION

LR (M2) provided the optimal diagnostic potency among other ML versions, multivariate analysis, and radiologists' performance on differentiation of schwannomas from GISTs.

Mesenchymal Tumors and Lymphoproliferative Diseases of the Stomach and Duodenum

Neoplasms of the stomach are classified into two large categories on the basis of the cell of origin: epithelial and nonepithelia. The vast majority of both benign and malignant tumors of the stomach are of epithelial origin, with mesenchymal and neuroendocrine tumors being much less common. The epithelial tumors arise from the mucosa while the nonepithelial tumors arise from the submucosa, muscularis propria, or serosa. The nonepithelial or intramural tumors of stomach include gastrointestinal stromal tumors, leiomyomas, schwannoma, granular cell tumors, glomus tumor, leiomyosarcoma, Kaposi sarcoma, lymphoma, and others. In this review, radiological appearance of mesenchymal tumors and lymphoproliferative tumors are described.

CT differentiation of gastric ectopic pancreas from gastric stromal tumor

Background

Gastric ectopic pancreas (GEPs) is a rare developmental anomaly which is difficult to differentiate it from submucosal tumor such as gastric stromal tumor (GST) by imaging methods. Since the treatments of the GEPs and GST are totally different, a correct diagnosis is essential. Therefore, we retrospectively investigated the CT features of them to help us deepen the understanding of GEPs and GST.

Methods

This study enrolled 17 GEPs and 119 GST, which were proven pathologically. We assessed clinical and CT features to identify significant differential features of GEPs from GST using univariate and multivariate analyses.

Results

In univariate analysis, among all clinicoradiologic features, features of age, symptom, tumor marker, location, contour, peritumoral infiltration or fat-line of peritumor, necrosis, calcification, CT attenuation value of unenhancement phase/arterial phase/portal venous phase (CTu/CTa/CTp), the CT attenuation value of arterial phase/portal venous phase minus that of unenhanced phase (DEAP/DEPP), long diameter (LD), short diameter (SD) were considered statistically significant for the differentiation of them. And the multivariate analysis revealed that location, peritumoral infiltration or fat-line of peritumor, necrosis and DEPP were independent factors affecting the identification of them. In addition, ROC analysis showed that the test efficiency of CTp was perfect (AUC = 0.900).

Conclusion

Location, the presence of peritumoral infiltration or fat-line of peritumor, necrosis and DEPP are useful CT differentiators of GEPs from GST. In addition, the test efficiency of CTp in differentiating them was perfect (AUC = 0.900).

Role of Multidetector CT Imaging in the Risk Stratification of Gastrointestinal Stromal Tumors (GISTs)–A Retrospective Analysis

Background Gastrointestinal stromal tumors (GISTs) are the most common gastrointestinal mesenchymal neoplasms which can arise from any part of the gastrointestinal tract (GIT) or an extraintestinal location. Size and the organ of origin are the major imaging inputs expected from the radiologist. However, it is worthwhile to find out which imaging characteristics on MDCT correlate with risk stratification. This knowledge would help the clinician in treatment planning and prognostication. The aim of this retrospective study is to evaluate the various MDCT imaging characteristics of GISTs and find out which parameters have significant association with risk and subsequent development of metastasis on follow-up whenever it was possible.

Materials and Methods This is a retrospective study conducted on 45 histopathologically proven cases of GIST from two institutions by searching from the digital archives. The following imaging parameters were analyzed: maximum size in any plane, organ of origin, shape (round, ovoid or irregular), margin (well-defined or ill-defined), surface (smooth or lobulated), percentage of necrosis, growth pattern, enhancement characteristics–both intensity (mild, moderate or significant) and pattern (homogenous vs. heterogenous), calcification, infiltration into adjacent organs, and presence of metastasis at presentation or on follow-up.

Results CT morphological parameters of significance in risk stratification as per our study include tumor necrosis, predominant cystic change, irregular and lobulated shape/surface characteristics, and adjacent organ infiltration.

The parameters which were associated with development of metastasis were size > 5 cm, necrosis > 30%, and the presence of adjacent organ infiltration.

Conclusion The radiologist has an important role in ascertaining the size of tumor as well as the organ of origin accurately to guide the clinician in risk calculation and subsequent prognostication. In addition, certain CT characteristics mentioned above, namely, tumor size, significant necrosis/cystic changes, irregular/lobulated contour, and invasion of adjacent organs, help in risk stratification and in predicting metastasis/poor prognosis.

Aneurysmal dilatation of colon: A rare imaging presentation of colon cancer

Aneurysmal dilatation of colon is a rare imaging feature of colon adenocarcinoma. Two cases with massive aneurysmal dilatation of the colon secondary to moderately differentiated adenocarcinomas are described. The 2 cases presented with asymmetric and progressive abdominal distension with no obstructive symptoms. Contrast-enhanced computed tomography of the abdomen and pelvis demonstrated marked aneurysmal dilatation of the involved segments of the colon and circumferential mural thickening. Colonoscopy found markedly dilated lumen in the involved segment of the colon. Histology of the biopsy specimens taken during colonoscopy revealed moderately differentiated adenocarcinoma with extensive infiltration of colon wall and damage of myenteric nerve plexus.

Thymic carcinoma metastasize to the small intestine: a case report

BACKGROUND

Thymic carcinoma is a rare mediastinal neoplasm with a high malignant potential. It often shows pleural invasion and distant metastasis. The metastasis of thymic carcinoma to the small intestine is rarely reported and difficult to distinguish from other gastrointestinal tract tumors.

CASE PRESENTATION

An elderly man presented with lower abdominal pain for 2 months. Abdominal CT showed a mass communicated with the small intestinal lumen. After radical resection of the small intestinal tumor, resected specimens showed moderately differentiated squamous-cell carcinoma with lymph nodes metastases. The patient received chest CT and was found to have a mass in anterior mediastinum. Biopsies of the mass revealed thymic squamous-cell carcinoma.

CONCLUSIONS

We highlighted the metastasis of thymic carcinoma to the small intestine is rare and easily misdiagnosed. In patients with a mass communicated with the small intestinal lumen, a suspicion of thymic carcinoma metastasis should not be overlooked and we should make accurate differential diagnosis from the other small intestinal tumors.

Gastric Calcifying Fibrous Tumor: An Easy Misdiagnosis as Gastrointestinal Stromal Tumor-A Systemic Review

Background and Objectives: Calcifying fibrous tumor (CFT) in the stomach is extremely rare and is easily misdiagnosed as a gastrointestinal stromal tumor (GIST). This study aims to determine the best method to differentiate between gastric CFT and GIST after a systemic review and meta-analysis. Materials and Methods: A systematic search of articles using electronic databases (MEDLINE, EMBASE, and LILACS) was conducted and resulted in 162 articles with 272 CFT cases published from January 1988 to September 2019. Results: Of these cases, 272 patients, 60 patients with gastric CFT (32 men and 28 women, mean age 49.2 years) were analyzed. The mean tumor size was 2.4 cm in patients with gastric CFT. Both endoscopic ultrasound (EUS) and computed tomography (CT) findings revealed well-defined (100% vs. 77.8%), heterogeneous (100% vs. 77.8%), iso-hypoechoic (71.4% vs. 33.3%), and calcified (85.7% vs. 77.8%) lesions, respectively. The majority of patients (53.3%) were symptomatic, with the most common symptom being abdominal discomfort (55.6%). None of the patients with gastric CFT showed recurrence after treatment, and most patients received nonendoscopic treatment (56%, n = 28/50). Both age and tumor size were statistically significant in patients with gastric CFT than GIST (49.2 vs. 65.0 years and 2.4 vs. 6.0 cm; both p < 0.001). The ratio of children among patients with CFT (5%) and GIST (0.05%) was also significantly different (p = 0.037). The calcification rates of gastric CFT had significantly higher calcification rates than GIST on images of EUS and CT (85.7% vs. 3.6% and 77.8% vs. 3.6%; both p < 0.001). Conclusions: Compared with patients with GIST, patients with gastric CFT were younger, had smaller tumor size, and were symptomatic. Furthermore, gastric CFT was well-defined, heterogeneous in the third layer, and had high calcification rates on the images.

Gastrointestinal stromal tumors (GIST): a proposal of a "CT-based predictive model of Miettinen index" in predicting the risk of malignancy

PURPOSE

To identify the predictors of malignancy on CT for the evaluation of gastrointestinal stromal tumors (GIST) by correlating CT findings with the mitotic index in order to propose a "CT-based predictive model of Miettinen index."

METHODS

One radiologist and one resident in radiology with 14- and 4-year experience in oncological field reviewed the CT findings of 42 patients by consensus, with respect to lesion site, size, contour, tumor growth pattern, enhancing pattern, degree of enhancement of tumor, percentage of tumor necrosis, mesenteric fat infiltration, ulceration, calcification, regional lymphadenopathy, direct invasion to adjacent organs, and distant metastasis. All parameters were correlated with the mitotic index evaluated at histopathological analysis following surgery. Normality of variables was evaluated using Shapiro-Wilk test. Pearson's correlation test was used to assess the interaction between variables. The diagnostic accuracy percentage of tumor necrosis was measured by receiver operating characteristic (ROC) analysis for detecting whether the number of mitosis per 50 high-power fields was > 5.

RESULTS

A significant statistical correlation was found between percentage of tumor necrosis and the mitotic index (p < 0.005), dimension, and location of the tumor.

CONCLUSION

CT could be an accurate technique in the prediction of malignancy of GIST in a CT risk assessment system, based on the location of the tumor, its size, and the percentage of tumor necrosis.

Periampullary duodenal schwannoma mimicking ampullary neoplasm

Schwannomas are neurogenic tumors that arise from Schwann cells in the neural sheath. Gastrointestinal schwannomas occur most often in the stomach, followed by the colon and the rectum. Duodenal schwannomas are rare amongst mesenchymal tumors of the gastrointestinal tract and only a few cases have been reported up to the current date with an incidence of approximately 2%-6%. Duodenal Schwannomas do not have characteristic imaging features thereby cannot be easily differentiated from other submucosal and adjacent extraluminal neoplasms. We present a case of a 76-year old male patient that presented to our hospital with abdominal pain and was diagnosed after an upper gastrointestinal endoscopy with an ampullary duodenal neoplasm that proved to be a periampullary duodenal Schwannoma on histopathology. Duodenal Schwannomas although rare should be considered in the differential diagnosis of ampullary neoplasms.

Retroperitoneal gastrointestinal stromal tumor: A case report and literature review

Retroperitoneal gastrointestinal tumor is the rarest subtype among 3 subtypes of extragastrointestinal tumors, which are uncommon stromal tumors. We herein report a case of a 55-year-old man with retroperitoneal gastrointestinal tumor detected by magnetic resonance imaging and confirmed by postoperative histology and immunohistochemistry.