Does a Glomus tumor stain with S-100 (S100 protein)?

From the Guidelines

No, a Glomus tumor typically does not stain with S100.

Key Characteristics of Glomus Tumors

• Instead, it is usually positive for smooth muscle actin and can also stain with CD34 and vimentin 1.
• S100 staining is more commonly associated with neural tumors, such as schwannomas 1.

Differential Diagnosis

• Glomus tumors can be differentiated from GISTs by their negativity for CD117 (c-kit) staining 1.
• The presence of S100 suggests a neural origin or Schwannoma, rather than a Glomus tumor 1.
• Immunohistochemical analysis is essential for establishing the diagnosis and differentiating Glomus tumors from other subepithelial masses 1.

From the Research

Glomus Tumor and S-100 Staining

• The majority of studies indicate that glomus tumors do not stain with S-100 protein 2, 3, 4.
• However, one study found that all samples of glomus tumors were positive for S-100 protein 5.
• The discrepancy in the results may be due to differences in the specific antibodies used or the tissue preparation methods.
• It is essential to consider the immunohistochemical profile of glomus tumors, including their positivity for muscle-specific actin and vimentin, and negativity for cytokeratins, desmin, and neurofilaments 2, 3, 4.

Immunohistochemical Characteristics

• Glomus tumors typically show positive immunohistochemical staining for:
  • Vimentin 2, 3, 6, 4
  • Smooth muscle actin (SMA) 3, 6, 4
  • Alpha-smooth muscle actin (α-SMA) 3
• Glomus tumors are usually negative for:
  • Cytokeratins (CK) 3, 6, 4
  • Epithelial markers 6
  • S-100 protein 2, 3, 4 (although one study found positivity 5)