Table of ContentsDefinition / general | Essential features | Epidemiology | Sites | Clinical features | Prognostic factors | Case reports | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Sample pathology report | Differential diagnosis | Board review style question #1 | Board review style answer #1
Cite this page: Gonzalez RS. Leiomyosarcoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/stomachleiomyosarcoma.html. Accessed December 8th, 2021.
Definition / general
- Malignant smooth muscle sarcoma that arises from the muscularis propria of the stomach
- Accounts for 1% of all malignant tumors of the stomach
- Rare malignant neoplasm with atypia, mitoses and necrosis histologically
- Positive for SMA and desmin
- Intermediate to poor prognosis
- Mainly middle aged men (Kathmandu Univ Med J 2006;4:510)
- Upper part of the body or the fundus of the stomach (Kathmandu Univ Med J 2006;4:510)
- Size of 5 cm or greater is a poor prognostic factor (Histopathology 2013;63:194)
- 50 year old woman with hypertension and diabetes presented with a submucosal gastric mass (Case #438)
Microscopic (histologic) description
- Composed of spindle cells with elongated nuclei and eosinophilic fibrillary cytoplasm arranged in fascicles
- Prominent atypia with enlarged, hyperchromatic and pleomorphic nuclei is seen with brisk mitotic activity and areas of necrosis (Odze and Goldblum: Surgical Pathology of the GI Tract, Liver, Biliary tract, and Pancreas, 3rd Edition, 2015)
Microscopic (histologic) images
Sample pathology report
- Stomach, antrum, resection:
- Leiomyosarcoma (6.4 cm) (see comment)
- Margins of resection unremarkable.
- Two benign lymph nodes.
- Comment: The tumor shows prominent nuclear atypia, numerous mitotic figures and regions of necrosis. Immunohistochemical stains for SMA and desmin are positive in the tumor. Leiomyosarcomas are rare in the stomach and risk factors for progression in this location remain poorly defined.
Board review style question #1
Which of the following is a poor prognostic indicator for leiomyosarcoma of the stomach?
- Greater than 20 mitoses per 10 high power fields
- Ki67 proliferative index above 50%
- Size greater than 5 cm
- Tumor necrosis