Primary leiomyosarcoma of the lesser sac--report of a case

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 arising in the lesser sac: report of a case

We describe herein a very rare case of leiomyosarcoma arising in the lesser sac. A 58-year-old man with a psychiatric disorder was admitted to our department for the investigation of epigastralgia and nausea which he had been suffering since the previous month. A laparotomy revealed that the abdominal mass, found on physical examination, was a primary lesser omental tumor, histological examinations of which confirmed a diagnosis of leiomyosarcoma. The tumor cells showed a DNA diploid pattern. Leiomyosarcoma of the lesser sac is extremely unusual and it is important that it be distinguished from an extraluminal tumor of the abdomen.