From the Guidelines
No, Glomus tumors typically stain positive for smooth muscle actin, but they are usually negative for S100 protein, as S100 is more commonly associated with tumors of neural origin or Schwannoma 1.
Key Characteristics of Glomus Tumors
- Stain positive for smooth muscle actin
- Usually negative for S100 protein Some key points to consider when evaluating subepithelial lesions include:
- Endoscopic appearance: No specific characteristics for Glomus tumors
- EUS layer: Typically found in the 2nd, 3rd, or 4th layer
- EUS appearance: Hypoechoic
- Histology: Spindle cells, similar to GIST, but with positive staining for smooth muscle actin and negative staining for CD117 and CD34 1. It's essential to note that while Glomus tumors do not typically stain positive for S100 protein, other tumors such as those of neural origin do stain positive for S100 protein 1.
From the Research
Immunohistochemical Characteristics of Glomus Tumors
- Glomus tumors have been studied immunohistochemically to determine their characteristics and differentiate them from other tumors.
- The studies 2, 3, 4, 5 consistently show that glomus tumors are negative for S100 protein.
- In addition to S100 protein, glomus tumors are also negative for other markers such as keratin, neurofilaments, Factor VIII-related antigen, and desmin in some cases 2, 3.
- However, glomus tumors are typically positive for smooth muscle actin and vimentin, which suggests a smooth muscle origin 2, 3, 4, 5.
Specific Studies
- A study of 23 cases of glomus tumors found that none of the tumors stained positive for S100 protein 2.
- Another study of 11 cases of glomus tumors also found that all tumors were negative for S100 protein 3.
- A case report of a glomus tumor of the stomach found that the tumor was negative for S100 protein, as well as other markers such as c-KIT, CD34, and desmin 4.
- A case report of a malignant glomus tumor of the palm found that the tumor was negative for S100 protein, as well as other markers such as cytokeratins, epithelial membrane antigen, and melanosome 5.
- A study of 16 glomus tumors found that some tumors were positive for S100 protein, but this was not a consistent finding across all cases 6.