Gastrointestinal Tract Perineurioma
Supplemental Studies
Immunohistology
| EMA |
>90% faint, focal |
| Claudin I |
>90% |
| Glut1 |
100% |
| Collagen type IV |
100% |
| CD34 |
15-30% |
- All four are markers of perineurial cells
- EMA requires high concentration, prolonged incubation and/or special antigen retrieval to give even a weak reaction
- Studies using normal EMA staining techniques and no other perineurial markers got negative results
- These studies resulted in the diagnosis of fibroblastic polyp
- It appears that fibroblastic polyp is identical to perineurioma in the GI tract
- Negative markers: S100, GFAP, caldesmon, CD1117/CKIT, smooth muscle actin, desmin, keratin
- Vimentin is strongly positive but nonspecific
Genetic study
- BRAF or KRAS mutations characteristic of hyperplastic polyps were demonstrated in 2/3 of cases studied (Agaimy)
- This suggests that GI perineuriomas are actually best considered mixed epithelial-stromal polyps
