Primary EGIST of the greater omentum - a rare presentation

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

Primary Extragastrointestinal Stromal Tumor of Greater Omentum with Intraperitoneal Bleeding

Gastrointestinal stromal tumors (GISTs) develop in the digestive tract, mainly in the stomach, small intestine, colon, or esophagus. However, primary tumors with the same pathologic features as GISTs have been reported to occur outside of the digestive tract and are called extragastrointestinal stromal tumor (EGIST). We herein report a rare case of EGIST arising from the greater omentum in a patient with abdominal pain caused by intraperitoneal bleeding from the tumor.

Imaging in gynecological disease (19): clinical and ultrasound features of extragastrointestinal stromal tumors (eGIST)

OBJECTIVE

To describe the clinical and sonographic characteristics of extragastrointestinal stromal tumors (eGISTs).

METHODS

This was a retrospective multicenter study. The data of patients with a histological diagnosis of eGIST who had undergone preoperative ultrasound examination were retrieved from the databases of nine large European gynecologic oncology centers. One investigator from each center reviewed stored images and ultrasound reports, and described the lesions using the terminology of the International Ovarian Tumor Analysis and Morphological Uterus Sonographic Assessment groups, following a predefined ultrasound evaluation form. Clinical, surgical and pathological information was also recorded.

RESULTS

Thirty-five women with an eGIST were identified; in 17 cases, the findings were incidental, and 18 cases were symptomatic. Median age was 57 years (range, 21-85 years). Tumor marker CA 125 was available in 23 (65.7%) patients, with a median level of 23 U/mL (range, 7-403 U/mL). The vast majority of eGISTs were intraperitoneal lesions (n = 32 (91.4%)); the remaining lesions were retroperitoneal (n = 2 (5.7%)) or preperitoneal (n = 1 (2.9%)). The most common site of the tumor was the abdomen (n = 23 (65.7%)), and less frequently the pelvis (n = 12 (34.3%)). eGISTs were typically large (median largest diameter, 79 mm) solid (n = 31 (88.6%)) tumors, and were less frequently multilocular-solid tumors (n = 4 (11.4%)). The echogenicity of solid tumors was uniform in 8/31 (25.8%) cases, which were all hypoechogenic. Twenty-three solid eGISTs were non-uniform, either with mixed echogenicity (9/23 (39.1%)) or with cystic areas (14/23 (60.9%)). The tumor shape was mainly lobular (n = 19 (54.3%)) or irregular (n = 10 (28.6%)). Tumors were typically richly vascularized (color score of 3 or 4, n = 31 (88.6%)) with no shadowing (n = 31 (88.6%)). Based on pattern recognition, eGISTs were usually correctly classified as a malignant lesion in the ultrasound reports (n = 32 (91.4%)), and the specific diagnosis of eGIST was the most frequent differential diagnosis (n = 16 (45.7%)), followed by primary ovarian cancer (n = 5 (14.3%)), lymphoma (n = 2 (5.7%)) and pedunculated uterine fibroid (n = 2 (5.7%)).

CONCLUSIONS

On ultrasound, eGISTs were usually solid, non-uniform pelvic or abdominal lobular tumors of mixed echogenicity, with or without cystic areas, with rich vascularization and no shadowing. The presence of a tumor with these features, without connection to the bowel wall, and not originating from the uterus or adnexa, is highly suspicious for eGIST. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

Bladder extragastrointestinal stromal tumor in an adolescent patient: A case-based review

Extragastrointestinal stromal tumors (EGISTs) are mesenchymal tumors occurring outside the gastrointestinal tract, with histological, immunohistochemical and molecular genetic characteristics similar to those of gastrointestinal stromal tumors (GISTs). The immunohistochemical examination usually demonstrates a positive expression for CD117. GISTs are rare neoplasms and EGISTs are even less common. This is the report of a case of EGIST in the urinary bladder of a 15-year-old adolescent female patient who presented with painless gross hematuria. Pelvic computed tomography revealed an irregular soft tissue density mass, sized 5.7×4.8 cm, in the bladder. Partial cystectomy was performed in April, 2011. There was no recurrence during follow-up over the next 35 months, as determined by transabdoninal ultrasonography and cystoscopic examination. The patient in this study did not receive any molecular-targeted drugs. To the best of our knowledge, this is the first reported case of an EGIST of the urinary bladder in an adolescent patient.

Retroperitoneal extragastrointestinal stromal tumor: radiologic pathologic correlation

Neoplasms with histology and immunohistochemistry similar to gastrointestinal stromal tumors may occur primarily outside the gastrointestinal tract, usually in the omentum and mesentery. These are referred to as extragastrointestinal stromal tumors (EGISTs). Retroperitoneum is a very rare site for such neoplasms. We report a patient with EGIST in the retroperitoneum, elaborating the cross-sectional imaging and histopathologic findings.

Stromal tumor of the lesser omentum : a case report

Gastrointestinal stromal tumors (GISTs) represent the majority of primary non-epithelial neoplasms of the digestive tract, most frequently expressing the KIT protein detected by immunohistochemical staining for the CD117 antigen. Extragastrointestinal stromal tumors (EGISTs), neoplasms with immunohistological features overlapping those of GISTs, are found in the abdomen outside of the gastrointestinal tract with no connection to the gastric or intestinal wall. We report the clinical, macroscopic and immunohistological features of an EGIST arising in the lesser omentum of a 58-year-old woman. This is a very rare location of intra abdominal stromal tumors.

An extragastrointestinal stromal tumor originating from the seminal vesicles: A case report and review of the literature

The present study reports a case of an extragastrointestinal stromal tumor (EGIST) originating from the seminal vesicles. A 74-year-old male patient with a tumor in the seminal vesicles underwent a radical spermatocystectomy due to an increased defecation frequency and a huge mass in the seminal vesicles. Ultrasonography and computed tomography (CT) initially diagnosed the mass as a tumor originating from the prostate. However, the mass was ultimately confirmed as an EGIST from the seminal vesicles following a laparotomy. According to the size, mitotic activity, cellularity, necrotic situation and immunohistochemical data, the tumor belonged to a low-risk group. No recurrence or metastasis has been identified during six years of follow-up observations. To the best of our knowledge, this is the first study to report this particular pathological type of EGIST.