IMMUNOHISTOCHEMISTRY, S100

What this test checks

Detects S100 protein, expressed in nerve sheath cells, Langerhans cells, melanocytes, and chondrocytes. Used to identify melanoma, nerve sheath tumours (schwannoma, neurofibroma), and some other tumour types.

Why do people get this test?

S100 is particularly valuable for diagnosing melanoma and nerve sheath tumours. Identifying these tumour types correctly is essential for choosing between surgery, targeted therapy, or immunotherapy.

When you should consider this test

• When melanoma is suspected in a tissue sample
• When classifying peripheral nerve sheath tumours
• As part of melanoma or neural tumour diagnostic panels

How to prepare

No preparation needed — performed on biopsy or surgical tissue.