Mucosal Benign Epithelioid Nerve Sheath Tumor
Definition
- Intramucosal infiltrate of S100 positive epithelioid cells lacking other neural elements
Diagnostic Criteria
- Lamina propria expanded by an infiltrate of epithelioid cells in 5/6 cases
- At least some cases have a spindled component
- Some extend into superficial submucosa
- One case entirely submucosal
- Pushing to infiltrating borders in 5/6 cases
- Surrounds and entraps crypts
- 1/6 cases encapsulated
- Uniform bland epithelioid cells
- Eosinophilic cytoplasm
- Uniform round to ovoid nuclei
- No atypia, pleomorphism or mitotic activity
- Frequent intranuclear pseudoinclusions
- No ganglion cells or axons in lesion
- No surrounding lymphoid cuff
- Extensively S100 positive
- CD34 positive in 3/5, described as supporting cells or lesional cells
- Illustration appears to show lesional cells stained
- Negative for CD117, calretinin, EMA
- Soft tissue schwannomas usually calretinin positive
- Only one case tested for EMA
- No axons on SM31 (neurofilament) stain
- All reported GI cases occur in the colorectum
- Most are distal
- 2-10 mm in size
- No relationship to familial syndromes
- Benign
- No recurrence
- At least one case of microcystic/reticular schwannoma reported by Liegl might be included in this group
- 1/5 cases reported was intramucosal
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting : November 29, 2009
