S100

S100 is found positive in melanoma, nerve sheath tumours, clear cell sarcoma of soft tissue, various histiocytic tumours, glial tumors and myoepithelial tumours (1).

Recommended Controls

The criteria for acceptable staining is both cytoplasmic and nuclear to indicate positive staining. The recommended control is the appendix, showing positive staining in the nerves and ganglion cells, schwann cells and adipocytes. A melonoma would be a high expressor.

Appendix 1

Malignant melanoma

Normal kidney

Tonsil

Disclaimer

These methods are intended as a guide only. Laboratories that wish to implement these methods should perform internal validation/verification prior to use. The RCPAQAP does not make any claim or warranty for the accuracy or performance of these methods.