Extragastrointestinal Stromal Tumors Research Articles

9182 Metastatic Extra-Gastrointestinal Stromal Tumor Presenting As Hypoglycemia

Abstract Disclosure: O. faour: None. D. John: None. S.K. Suryanarayanan: None. A.A. Rizvi: None. Introduction: Non islet cell tumor hypoglycemia (NICTH) is a rare paraneoplastic syndrome seen in association with solid abdominal tumors of mesenchymal and epithelial origin. We report a case of metastatic extra-gastrointestinal stromal tumor (E-GIST) presenting with severe hypoglycemia as its initial manifestation. CASE DESCRIPTION: A 46-year-old patient was found to have a blood glucose of <45 mg/dl during a routine clinic visit with her primary care physician. Although she was asymptomatic, she was sent to the emergency room (ER) for further evaluation. She had a history of prediabetes managed by lifestyle modification. She has been experiencing multiple episodes of hypoglycemia previously which fulfilled the Whipple’s triad in the preceding months. These hypoglycemic episodes included loss of unconsciousness, falls in the shower with head injury, and several hospital visits. Serum glucose in the ER was 14 mg/dl and hypoglycemia persisted despite continuous dextrose solution. Physical examination was notable for a distended, non-tender abdomen and cervical lymphadenopathy. CT scan showed a 15 cm mass in the liver, multiple large masses in the mesentery, and a 11 cm lesion in the left pelvis. There were enlarged lymph nodes in the abdomen, chest, and neck. Serum chemistries drawn when the patient was hypoglycemic revealed potassium level of 2.7 mg/dl (3.5-5.5) an insulin level of <1.0 mIU/L (5-25), C-peptide <0.1 ng/mL (0.5-2), cortisol 13.8 mcg/dL (5-25), and insulin-like growth factor-2 (IGF-2) was 270 ng/mL (38-267). The IGF-2/IGF-1 molar ratio was 3.4 (normal <3:1). The sulfonylurea drug screen came back negative. Upper and lower endoscopies were unrevealing. Biopsy of the liver lesion showed cytology and immunohistochemical findings consistent with a epithelioid metastatic extra-gastrointestinal stromal tumor. A provisional diagnosis of NICTH was made. The patient responded well to intravenous glucose, oral carbohydrate intake and high-dose corticosteroids. She was subsequently started on therapy with the tyrosine kinase inhibitor (TKI) imatinib. Discussion: Paraneoplastic hypoglycemia is often seen in association with metastatic epithelial and mesenchymal tumors. IGF-2 and incompletely processed pro-IGF-2 activates autocrine, paracrine, and endocrine pathways that lead to tumor growth, fasting hypoglycemia, rarely of acromegalic features. Treatment with octreotide, diazoxide, and glucagon is generally ineffective, while glucocorticoid use and surgical intervention are helpful in ameliorating the hypoglycemia. Tumor-directed therapy with TKIs, primarily imatinib, appears promising in achieving remission. Our case is a clinical reminder that hypoglycemia secondary to NICTH can be the predominant presenting feature in patients with underlying E-GIST. Presentation: 6/3/2024

Clinical case of a giant extragastrointestinal tumor of the retroperitoneum and review of the literature

Extragastrointestinal stromal tumors (EGIST) are rare lesions in the mesenchymal neoplasm, accounting for less than 1% of the primary neoplasias of the digestive tract. In only 10% of the cases EGIST may affect any segment of the gastrointestinal tract and can occur in other locations (omentum, mesentery, or retroperitoneum, GIST arising from the pancreas). The incidence is approximately 14.5 patients per 1 million persons [1–3]. To date, more than 190 cases have been published. We reported a rare case of huge mesenteric extra-gastrointestinal stromal tumor presenting as a peritoneal mass in a 53-year-old patient

Computed tomography-based contrast features for distinguishing extra-gastrointestinal stromal tumors from intra-abdominal fibromatosis.

This study aims to define the computed tomography (CT) criteria that distinguish extra-gastrointestinal stromal tumors (eGISTs) from intra-abdominal fibromatosis (IAF). Retrospective analysis was conducted on CT images obtained from 31 pathologically confirmed cases, including 17 cases of eGISTs and 14 of IAF. Various parameters [e.g., lesion location, contour characteristics, border delineation, enhancement patterns, presence of intralesional necrosis, vessels, air, fat, and hemorrhage, the long diameter (LD), LD/short diameter (SD) ratio, and volume (LD × SD × height diameter)] were meticulously evaluated. In addition, the degree of enhancement during arterial and portal venous phases and the lesion-to-aorta CT attenuation ratio during both phases were quantified. Statistical analysis was performed using Fisher's exact test, the Student's t-test, and the receiver operating characteristic curve to identify significant CT criteria. Sensitivity and specificity assessments were conducted for single and combined CT criteria. Significant differentiators between eGISTs and IAF include non-mesenteric localization, irregular contour, well-defined borders, heterogeneous enhancement, presence of intralesional necrosis and vessels, and absence of intralesional fat, with LD exceeding 9.6 cm, an LD/SD ratio >1.22, and volume surpassing 603.3 cm3 (P < 0.05). A combination of seven or more of these criteria yielded a specificity of 100%. Ten distinct CT criteria have been identified to distinguish eGISTs from IAF, notably encompassing non-mesenteric localization, irregular contour, well-defined borders, heterogeneous enhancement, presence of intralesional necrosis and vessels, absence of intralesional fat, LD >9.6 cm, an LD/SD ratio >1.22, and volume surpassing 603.3 cm3. The current findings establish CT criteria to distinguish eGISTs from IAF in a clinical setting.

An Unpropitious Surprise Post Vaginal Hysterectomy – A Case of Incidentally Discovered Extra-Gastrointestinal Stromal Tumour

Extra-gastrointestinal stromal tumours (EGIST) are rare mesenchymal tumours that arise outside the gastrointestinal tract and mainly affect the omentum, mesentery, and retroperitoneum. We report a case of EGIST in an elderly female patient at an unusual location. The patient was referred to our centre with hemoperitoneum post vaginal hysterectomy for the treatment of third-degree utero-vaginal prolapse. Ultrasonography (USG) of abdomen and pelvis was done which revealed a heterogenous tumour in the upper abdomen. The tumour mass measured 23x18x8.5cms and was abutting the greater curvature of stomach without infiltration. A diagnosis of extra-gastrointestinal stromal tumour, spindle cell type, high grade, with pseudo signet ring appearance was rendered based on the morphology and immunohistochemistry with CD117(c-kit) and DOG1. Rupture of cancerous mass in the abdomen is one of the causes to be kept in mind in hemoperitoneum and EGIST should be considered in the differential diagnosis of large, multi-nodular, primary lesions of the abdomen. A high degree of suspicion is needed as these patients present late and are often diagnosed incidentally during investigations for unrelated medical conditions. 10% of EGISTs are primarily disseminated and the site of origin cannot be established with certainty, emphasizing the enigma of its origin as encountered in the present case.International Journal of Human and Health Sciences Vol. 08 No. 02 Apr’24 Page: 207-211

A rare case of extragastrointestinal stromal tumor of vocal cord - case report.

Gastrointestinal stromal tumors (GISTs) are the mesenchymal tumors of the gastrointestinal tract. Extra Gastrointestinal stromal tumors (EGISTs) are rare neoplasms that occur outside the gastrointestinal tract [1]. Miettinen et al. [2] described the first EGIST in 1999. EGIST accounts for 10% of all GISTs [3]. The main distinction between GIST and EGIST is the site of origin of the primary tumor, as GIST occurs throughout the GI tract, from the esophagus to the anus, whereas EGIST is a tumor without any connection with the intestinal wall and are reported in the retroperitoneum, mesentery, and omentum [4]. Hu et al. [5] reported a first case report of EGIST of larynx.We present a second case report of Extra-gastrointestinal stromal tumor of larynx a 47-year-old male reported to ENT Department Command Hospital Central Command Lucknow with complaints of Hoarseness. On examination found to have right vocal cord growth for which he underwent excision of right vocal cord growth. Histopathological examination showed typical of a spindle-cell GIST, showing strong immunoreactivity for CD 117, DOG1, Vimentin and CD 99. 6 months follow up post surgery with no recurrence.

Extra gastrointestinal stromal tumor with unusual size and rare localization: a case report

Extra gastrointestinal stromal tumor with unusual size and rare localization: a case report

Extra Gastrointestinal Stromal Tumour (EGIST) of Chest Wall Detected on 18F-FDG PET/CT: A Case Report and Brief Review of Literature

Gastrointestinal stromal tumors (GIST) are rare tumors accounting for less than 1% of primary neoplasia of the digestive tract. They can also occur outside the GIT, where they are called extra gastrointestinal stromal tumors (EGIST), which are extremely rare tumors. GISTS and EGISTS have similar histo-pathological and molecular profiles. Though these are known to be FDG avid, some of the atypical GISTS can be FDG negative or only minimally FDG avid. Here, an unusual case of a 57-year-old female with FDG avid solitary chest wall mass is presented, which after biopsy and immune-histochemistry was proven as EGIST. She underwent en block resection of the tumor and is presently on adjuvant treatment with Imatinib mesylate. This case report highlights the importance of considering EGIST as a differential diagnosis of a solitary chest wall mass and the utility of 18FFDG PET/CT in its management.

Survival analysis of extragastrointestinal stromal tumors based on the SEER database: a population-based study.

Extragastrointestinal stromal tumors (EGISTs) are rare mesenchymal neoplasms that originate outside the gastrointestinal tract. However, the population-level survival analysis of EGIST remains poorly grasped. Therefore, we aimed to analyze the survival of EGIST patients using the Surveillance, Epidemiology, and End Results (SEER) database. All patients diagnosed with GIST and EGIST between 2000 and 2019 were identified through utilization of the SEER database. Missing data were handled using multiple imputation methodology. Kaplan-Meier analyses and Cox proportional hazard models were employed to assess the influence of demographic and clinical characteristics on both overall survival (OS) and cancer-specific survival (CSS). A total of 13,330 patients were enrolled in the study, comprising 12,627 diagnosed with GIST and 703 with EGIST. EGIST patients demonstrated significantly poorer OS [hazard ratio (HR) 1.732, 95% confidence interval (CI) 1.522-1.970, P < 0.001] and CSS (HR 2.167, 95% CI 1.821-2.577, P < 0.001) compared to GIST patients. The mean 1-year, 3-year, 5-year, and 10-year OS rates for EGIST patients were 78.3%, 61.9%, 50.5%, and 32.5%, respectively, with corresponding mean CSS rates of 84.3%, 70.8%, 61.3%, and 46.5%. Multivariate Cox regression analysis identified age, race, sex, grade, size, and surgical type as independent risk factors for OS in EGIST patients, while age, sex, year of diagnosis, grade, surgical type, and radiation therapy were identified as independent risk factors for CSS. Patients with EGIST who underwent surgical treatment exhibited significantly higher 5-year OS rates (49.0% vs. 39.9%, P = 0.035) and CSS rates (63.9% vs. 53.0%, P = 0.028) compared to those who did not undergo surgery. EGIST patients have a poorer prognosis compared to GIST patients; however, surgical treatment has been shown to improve the prognosis.

Epithelioid extragastrointestinal stromal tumor in the pelvic cavity: A rare case at a rare location

ABSTRACT Extraintestinal gastrointestinal stromal tumors (EGISTs) are rare stromal tumors involving mesentery, omentum, and retroperitoneum. EGISTs of the pelvic cavity are extremely uncommon, and till date, no case of pure epithelioid type arising from the pelvic cavity has been reported. They pose a diagnostic pitfall as they may mimic ovarian malignancy. We present a unique case of an epithelioid extraintestinal stromal tumor arising from the pelvic cavity. A 43-43-year-old woman presented with complaints of abdominal pain and menstrual irregularities. Ultrasound examination revealed a large well-defined hypoechoic mass in the right pelvic cavity with a possible site of origin from the right ovary. A total hysterectomy with bilateral salpingo-oophorectomy was done. Histopathological examination revealed an encapsulated tumor comprising predominantly of nests and lobules of epithelioid cells with round-to-oval nuclei, vesicular chromatin, and moderate amount of eosinophilic to clear cytoplasm. Mitotic activity was brisk along with focal areas of necrosis. On immunohistochemistry, tumor cells were diffusely and strongly positive for DOG1 and CD117. They were negative for smooth muscle actin, vimentin, S-100, and HMB-45. Based on these findings, a final diagnosis of the high-grade GIST epithelioid variant was made. It is crucial to make the correct preoperative diagnosis of GIST, since these patients may benefit from neoadjuvant imatinib, especially in case of large tumor size.

Gastrointestinal Stromal Tumors: Our Ten-Year Experience of a Single-Center Tertiary Hospital.

Gastrointestinal stromal tumors (GISTs) are the most frequent mesenchymal neoplasms of the gastrointestinal tract. They have variable clinical presentation, prognosis, and molecular characteristics. Here, we present the results of our retrospective study including patients operated on for GIST during the last decade. All the patients who underwent GIST resection during the decade 2008-2018 were included in the study. The diagnosis was based on the pathology report. All the data were collected and analyzed statistically using the Statistical Package for Social Science v25.0. Finally, after having applied the proper search terms, a comprehensive review of articles published in the Medline database was held. Thirty-two patients (sixteen women) were included in the study with a mean age of 69.6 years old (SD = 13.9). Twenty-one patients had a GIST in the stomach, eight in the small intestine, and three had an extra GIST. Of the 29 patients contacted, 21 were alive with a mean survival time of 74.3 months (SD = 49.6 months, min: 3.0 months, max: 161.0 months), whereas eight patients passed away. Finally, 13 patients were treated with tyrosine kinase inhibitors (TKIs) of whom only one died, while 9 patients passed away from those treated with surgery alone (p = 0.031). Our results were in concordance with the existing data in the literature. GISTs require patient-based therapeutical management depending on the histology of the tumors. Gastric tumors present a better prognosis than those localized in the intestine, while the use of TKIs has led to an improvement in patient survival rate.

Anal Reconstruction in a Rare Case of Perianal Extragastrointestinal Stromal Tumors

ABSTRACT Gastrointestinal stromal tumors (GISTs) are rare (10/15 cases per million worldwide). Anal GIST is still rarer (16 cases reported in journals). Extra-GISTs form only 1% of GISTs. Perianal extragastrointestinal stromal tumors (EGISTs) are uncommon among EGISTs with hardly any reported cases. The authors are presenting a case of recurrent perianal EGIST which was treated by wide local excision leaving a defect involving half of the circumference and full length/thickness of anal canal and anal sphincters anteriorly. As against the common practice of reconstruction with dynamic muscle transfer, usually gracilis or gluteus, the defect was repaired with levatoroplasty and Limberg skin flaps. Anal sphincter remnants were pulled and opposed esp. at the cephalic end or anchored onto the levators. The patient achieved full anal continence in a year. The authors would like to suggest it as a method of choice for anal GIST and perianal EGIST.

Primary extragastrointestinal stromal tumor of the prostate: review of the literature and case report.

A 58-year-old man was presented with lower urinary tract symptoms for 6 months. A digital rectal examination revealed a markedly enlarged prostate with a smooth, bulging surface. Prostate-specific antigen density was 0.5ng/ml. MRI of the prostate showed an enlarged prostatic mass with hemorrhagic necrosis. Transrectal ultrasound-guided prostate biopsy was performed and pathological reports suggested a gastrointestinal stromal tumor. The patient refused radical prostatectomy and received only imatinib treatment. The diagnosis of EGIST of the prostate is extremely rare and depends on the histopathologic features with immunohistochemical results. The treatment is essentially based on radical prostatectomy, but there are other therapeutic modalities associating surgery with adjuvant or neoadjuvant chemotherapy. For patients refusing surgery, treatment with imatinib alone appears to be a therapeutic solution. Despite the rarity, EGIST of the prostate should be included in the differential diagnosis of patients presenting with lower urinary tract symptoms. There is no consensus regarding the treatment of EGIST, and the patients are treated as per the risk stratification.

Extra-gastrointestinal stromal tumors (EGISTs): A case report for a mischief entity.

Extra-gastrointestinal stromal tumor is a rare subtype of soft tissue sarcomas with significantly variable presentation, management, and prognosis. This makes it crucial to report the different institutional experiences of encountering extra-gastrointestinal stromal tumors (EGIST). We report 3 cases of EGIST diagnosis at American University of Beirut Medical Center for 2 males and 1 female in the 5th, 6th, and 7th decades of life, respectively. For the first case, the tumor was initially suspected to be ovarian cancer, but biopsy revealed a diagnosis of EGIST, and the patient was started on neoadjuvant therapy. In the second case, the tumor was retro-gastric and prelim diagnosis was gastric cancer but again biopsy revealed an EGIST histopathology, and the patient underwent surgery and adjuvant treatment. For the third case, a previous history of testicular cancer prompted an initial suspicion of recurrence with metastasis but biopsy and immunohistochemistry staining revealed EGIST with related markers. The patient underwent treatment at a different institution in his home country. This report sheds light on the importance of keeping EGIST amongst any differential list for abdominal and pelvic tumors. It also shows that EGIST-focused studies are needed to assess the effectiveness of the different treatment modalities available when utilized specifically for EGIST. This would allow for better oncological outcomes and improved quality of life.

Primary extra-gastrointestinal stromal tumor of retroperitoneum: Clinicopathologic characteristics and prognosis of six cases.

This study investigates the clinicopathological features and prognostic genic biomarker factors of primary retroperitoneal extra-gastrointestinal stromal tumors (EGISTs). The clinicopathological data of six patients with primary retroperitoneal EGIST were analyzed, including cell type (epithelioid or spindle), mitoses, and the presence of intratumoral necrosis and hemorrhage. Mitoses were counted and summed from 50 high power fields (HPFs). Mutations of exons 9, 10, 11, 13, 14, and 17 of the C-kit genes and those of exons 12 and 18 of the PDGFRA gene were examined. Follow-up was performed via telephone, and all outpatient records were reviewed. The last follow-up date was February 2022, the median follow-up was 27.5m and the postoperative status, medication, and survival of the patients were recorded. The patients were treated with radical intent. Four cases (patients 3, 4, 5, and 6) underwent multivisceral resection for encroachment on the adjacent viscera. The postoperative pathological results demonstrated that all biopsy specimens were negative for S-100 and desmin, and positive for DOG1 and CD117. Additionally, four patients (case 1, 2, 4, and 5) were positive for CD34, four (case 1, 3, 5, and 6) were positive for SMA, four (case 1, 4, 5, and 6) had >5/50 HPFs, and three (case 1, 4, and 5) had Ki67 >5%. According to the modified National Institutes of Health (NIH) guidelines, all patients were graded as high-risk cases. By exome sequencing, exon11 mutations were detected in the six patients, while exon10 mutations were detected in two cases (patients 4 and 5). The median follow-up time was 30.5 (11-109) months, with only one fatality at 11 months. Retroperitoneal EGIST is a rare mesenchymal tumor that is difficult to distinguish from other retroperitoneal tumors. To diagnose this highly malignant tumor, low-threshold suspicion is necessary, and Kit and PDGFRA gene mutations should be routinely tested to confirm the diagnosis and guide subsequent treatment.

Primary Extra-Gastrointestinal Stromal Tumors (E-GIST) of the Liver, about Two Cases and Review of the Literature Oncology Hospital Experience at Chu Hassan II in FES

Introduction: Primary extra-gastrointestinal stromal tumors (E-GIST) of the liver are rare. The clinical presentation can range from asymptomatic to bleeding or manifestations of mass effect. Cancer surgery followed by adjuvant treatment with imatinib is the standard of care. However, in special circumstances, a cytoreductive approach may represent a therapeutic option. We describe here the case of two patients who presented with a painful and protruding epigastric mass, the first case was a localized E-GIST candidate for neoadjuvant treatment with imatinib with complete resection surgery thereafter with very good evolution, and the second is that of an E-GIST of the liver at an advanced stage with an evolution very quick to death. Conclusion: Primary liver E-GIST is a rare condition. Treatment is based on systemic therapy and total resection surgery. However, cytoreductive surgery will be required when complete resection is not possible.

A Rare Case of Gastrointestinal Stromal Tumor of the Abdominal Wall

Gastrointestinal stromal tumors (GIST) are rarely encountered in medical practice, developing with predilection in people over 40 years old. Their starting point is found in the digestive tract, and can appear anywhere along it. Normally, in the human body cells go through the processes of development, division and then apoptosis. In the case of gastro-intestinal stromal tumors, the cells divide continuously and the process of apoptosis is no longer carried out, forming these tumors, which can be benign or malignant. The essential medical treatment used in the case of gastrointestinal stromal tumors is Imatinib, which has the role of preventing the growth or even regression in size of the tumor in most cases. The specificity marker for GIST is represented by c-KIT protein, and immunohistochemically, the majority of gastrointestinal stromal tumors show positivity for CD34 and c-KIT. There are also extragastro-intestinal stromal tumors, for example located in the liver, duodenum, pancreas, but they are extremely rare, being considered rather as metastases from the primary tumor.

An Extragastrointestinal Tumor Diagnosed as a Vaginal Mass during Pregnancy

We report a case of an extragastrointestinal stromal tumor diagnosed as a vaginal mass during pregnancy. The mass was detected during routine examination at 24 weeks of gestation. At 26 weeks, the patient underwent transvaginal ultrasonography and magnetic resonance imaging, which revealed a blood flow-rich mass of approximately 50 × 30 mm in the rectovaginal septum. At 29 weeks of gestation, we resected the mass vaginally and the pathological diagnosis was a gastrointestinal stromal tumor. Chemotherapy was withheld until after full-term birth because the proliferation index of the tumor cells was low. The patient delivered a healthy infant. Imatinib was commenced at 1 month postpartum, with no recurrence or metastasis after 2.5 years. An extragastrointestinal stromal tumor as a vaginal mass in pregnancy has not been reported; however, our case suggests that the tumor should be considered a differential diagnosis of a vaginal mass in pregnancy.

S2210 A Rare Retroperitoneal Mass Simulating a Complicated Diverticulitis

Introduction: Extra-gastrointestinal stromal tumors (EGISTs) are a group of rare neoplasm that arises from cells outside the gastrointestinal (GI) tract but with similar pathologic characteristics as of gastrointestinal stromal tumors (GISTs). They account for only 5% of all GISTs involving the retroperitoneum, mesentery or omentum. EGISTs typically presents as large intra-abdominal masses with unspecific symptoms and are known to have a more aggressive behavior than its GI counterpart. Case Description/Methods: A 50-year-old male inmate with no medical history presents to the ED after having unquantified episodes of non-bloody, non-watery diarrhea and vomiting of gastric content for 5 days prior to admission. The patient also reports subjective fever and constant left quadrant abdominal pain. Upon physical exam, he was found with signs of dehydration, a distended abdomen with hyperactive bowel sounds, and a non-mobile large mass on the left lower quadrant with tenderness to light palpation. Laboratories were remarkable for neutrophilic leukocytosis, thrombocytosis, and elevated inflammatory markers. Abdomino-pelvic CT revealed a large left heterogeneously enhancing retroperitoneal mass with central necrosis measuring 18.6 cm AP x 18.4 cm transverse x 25.3 cm CC causing mass effect over the left kidney with loss of intervening fat planes, flattening of the left adrenal gland and displacement of the stomach, small and large bowel with almost complete collapse of the distal transverse and descending colon. Core-needle biopsy revealed high-risk GIST with positive immunohistochemistry for C-KIT, CD34, CD56, actin, and desmin with a very high mitotic index (45 mitosis/25 HPF). Surgery was deferred due to large size of mass and closure to adjacent structures. Neoadjuvant therapy with Imatinib was started but patient was lost to follow up upon discharge. Discussion: This case describes a rare presentation of EGIST emerging from the retroperitoneum with a positive immunohistochemistry for desmin and manifesting as a complicated diverticulitis. Although there is limited data about its origin, EGISTs and GISTs are recognized to be molecularly identical. Furthermore, because EGISTs are found outside the GI system, symptoms only appear when the tumor has progressed to an advanced stage giving it a worse prognosis. As a result, having EGIST as a differential diagnosis for abdominal mass is crucial. More research is needed to better understand the behavior, prognosis, and treatment options of these tumors.

Mesenteric lymphoma - a case report

Gastrointestinal stromal tumors (GISTs) comprise a group of smooth muscle mensenchymal alimentary tract tumors of variablemalignancy (1) GISTs may ouccur anywhere along the gastrointestinal tract, they are most commont located in the stomach (50-60%) and the small intestine (30-35%), and less frequenty in the colon, rectum and esophagus (2). More rarely, GISTs may arisefrom other intra-abdoment soft tissues within the abdominal cavity, usually in the omentum, mesentery or the retroperitoneumcalled extra-Gastrointestinal stromal tumors (EGIST). Three macroscopic growth patterns of GIST: intraluminal, exophytic(extraluminal), and transmural tumors with the distribution was even (3).In this study, we describe case report of 70-year-old man was admitted to our hospital because of abdominal pain over 6months with no pathological antecedent. Abdominal ultrasound (US) reveal a omental solid mass in left lumbar region, andon CT scan show a solid mass in left lumbar region in front of the descending colon, maesuring around 50x87x133mm withwell-circumscribed, slight enhance with intravenous contrast, no hemmorrage or necrosis area, no calcification and not clearlyseparated from small-bowel. Patient has laparoscopic surgeon, diagnosis was a pedunculated exoluminal gastrointestinal stromal tumor (GIST). Histopathological examination report and the CD-117 immunoreactive score is suitable of endoscopicallyinvisible medium sized.

Morphological and immunohistochemical diagnostic of extragastrointestinal stromal tumors - a 51 case series analysis.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the digestive tract, originating from structures differentiating towards Cajal cells. Due to their morphology and localization, the extragastrointestinal stromal tumors (EGISTs) can be a diagnostic challenge. We investigated a series of 51 EGISTs diagnosed in our institutions, aiming to explore the immunophenotypes and to analyze the process and the utility of the antibodies required for a positive diagnosis. Immunohistochemical examinations were done for pan-cytokeratin (pan-CK), Ki67, discovered on GIST1 (DOG1) protein and platelet-derived growth factor receptor alpha (PDGFRA), as necessary. The main tumor site was abdominal wall in 43 (84%) cases, most of the tumors showed spindle cell cellularity, followed by mixed and epithelioid type. Twenty-six cases revealed a full conventional immunohistochemical profile with DOG1 positivity. In 10 cases, c-KIT expression was absent but with the preservation of cluster of differentiation (CD)34 positivity, and eight cases were positive for PDGFRA. In our study, we found a subgroup of eight cases presenting in extra-abdominal settings (including one in lung and two in the head-and-neck area). We concluded EGISTs represent a histopathological and immunohistochemically challenging subgroup testing more often negative for c-KIT mutations and positive for PDGFRA compared to GIST. DOG1 remains the marker of choice regardless of tumor site, while CD34 and CD117 should be considered as adjuvants.