Gastrointestinal Tract Leiomyosarcoma
Definition
- Malignant smooth muscle neoplasm arising in the gastrointestinal tract
Diagnostic Criteria
- Fascicles of spindle cells
- Moderate to abundant eosinophilic cytoplasm
- Oval to moderately elongate nuclei
- Frequently blunt-ended
- Mild to marked cytologic atypia
- Mitotic rate >5/50 HPF appears to be the most important criterion
- Most cases have >50/50HPF mitotic figures
- Very few cases <26/50HPF
- Size is not a criterion for aggressive behavior
- Range 2-19 cm
- May form polypoid intraluminal masses
- Leiomyosarcomas rare at all GI sites
- CD117 and DOG1 negative
- Any stromal neoplasm of the GI tract expressing CD117 or DOG1 should be considered a GIST
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting/updates: 12/5/09, 11/27/09
