Primary leiomyosarcoma arising in the lesser sac: report of a case

The Lesser Sac and Foramen of Winslow: Anatomy, Embryology, and CT Appearance of Pathologic Processes

OBJECTIVE. This article reviews the embryologic development, relevant anatomy, and imaging features, on CT, of pathologic processes involving the lesser sac and foramen of Winslow. CONCLUSION. The lesser peritoneal sac is an intricate anatomic region involved in many disease processes. It is a significant conduit for the spread of disease within the peritoneal cavity. The spectrum of pathologic processes pertaining to the lesser sac can be classified on the basis of the type of involvement, such as a fluid collection (e.g., transudate, exudate, bile, and blood), a mass (e.g., neoplastic or nonneoplastic conditions and lymphadenopathy), or an internal hernia into the lesser sac.

First Account of Primary Leiomyosarcoma of the Lesser Omentum since Establishment of c-Kit Mutations in Gastrointestinal Stromal Tumors

Background

Primary omental leiomyosarcoma is an extremely rare type of tumor. Leiomyosarcomas originating from the lesser omentum have not been reported since immunohistochemical staining for c-kit has been used for the diagnosis of mesenchymal abdominal tumors. They are yet to be reported since gastrointestinal stromal tumors were categorized. Here we reported a case of successful resection of a lesser omental leiomyosarcoma.

Case Presentation

A 71-year-old man underwent ultrasonography at the outpatient clinic through which an upper abdominal tumor was identified. Following computed tomography and endoscopy, a 4.5 cm submucosal tumor in the lesser curvature of the stomach was highly suspected. A laparoscopic partial resection of the stomach was performed. Histopathological examination revealed the tumor to be a leiomyosarcoma arising from the lesser omentum that did not invade the stomach. Immunohistochemical staining showed that the tumor was negative for CD34, c-kit, and S-100 and positive for desmin and α-smooth muscle actin. No recurrence had been observed 1 year after surgery without adjuvant chemotherapy.

Conclusions

Primary lesser omental leiomyosarcoma, which is difficult to diagnose before surgery given the location of the primary tumor in the lesser omentum, has rarely been reported. Considering the high possibility of malignancy, close observation is essential.

Primary leiomyosarcoma of the omentum presenting as an ovarian carcinoma, case report and review of the literature

Primary omental leiomyosarcoma is a rare tumor. We report a case of successfully resected omental leiomyosarcoma whose presentation mimicked ovarian carcinoma. Symptoms of abdominal distension and discomfort that lasted 8 months followed by pain lead to a diagnosis of a large mass in the abdomen. Physical examination revealed a large, over 20 cm tumor, suspected to be of ovarian origin. A small amount of ascites was found on Computerized Tomography (CT) and ultrasound (US) scans. Total abdominal hysterectomy with bilateral salpingo-oophorectomy, omentectomy and tumor debulking procedure was planned. Laparotomy revealed normal uterus ovaries and tubes with a leiomyosarcoma of the omentum which was completely resected successfully. Only 26 cases of primary leiomyosarcoma of the omentum were previously described in the literature. A review of the literature is also presented.

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Primary leiomyosarcoma of the omentum can mimic the presentation of an ovarian carcinoma.

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The diagnosis is based mostly on the appearance on Computerized Tomography scan and angiography.

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Complete surgical resection of this tumor can lead to long term survival.

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

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

The anatomy and pathology of the lesser sac: implications for peritoneal dialysis

Pathological conditions involving the lesser sac of the peritoneal cavity in patients on peritoneal dialysis (PD) can pose significant diagnostic and therapeutic challenges. Lack of appreciation of these challenges may delay diagnosis and compromise outcome. A case series by Li and colleagues in this issue of Peritoneal Dialysis International highlights the diagnostic challenges presented by lesser sac infection in PD patients, and in this accompanying commentary we discuss the development and anatomy of the lesser sac, as well as the pathological conditions and investigations relevant to the management of patients on PD.