Gastrointestinal Tract Leiomyoma
Definition
- Benign smooth muscle neoplasm arising in the gastrointestinal tract
Diagnostic Criteria
- Fascicles of uniform spindle cells
- Moderate to abundant eosinophilic cytoplasm
- May contain eosinophilic globules
- Elongate nuclei frequently blunt-ended
- At most, focal cytologic atypia
- Rare cases reported with large hyperchromatic “symplastic” nuclei
- Mitotic rate ≤5/50 HPF appears to be the most important criterion
- Most cases have no mitotic figures
- Nearly all leiomyosarcomas have rates well above 5/50HPF
- No coagulative tumor cell necrosis
- Size is not a criterion for aggressive behavior
- Range 0.1-18 cm
- Leiomyomas vary in their incidence by site
- They are more common than GIST in the esophagus
- Most are intramural (involving muscularis propria)
- Intramural tumors occur rarely at other GI sites
- Muscularis mucosae leiomyomas are common in the rectum
- They occur rarely at other sites
- Essentially all smooth muscle tumors limited to the muscularis mucosae are benign
- GIST are never limited to the muscularis mucosae
- All leiomyomas are rare at other 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, 11/27/11
