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  • S100

S100 is an antibody marker that reacts with antigens present in conditions like melanoma. S100 is normally present in cells derived from the neural crest like Schwann cells, and melanocytes, chondrocytes, adipocytes, myoepithelial cells, macrophages, Langerhans cells, dendritic cells, and keratinocytes. It may be present in some breast epithelial cells. This is very useful to identify tumour origins as a neural origin but does require to be used as part of a panel in IHC due to the large number of cells it reacts with.

The staining pattern of S100 is Nuclear and Cytoplasmic as shown below.

Picture 1 – S100 positivity in Clear cell tumour in kidney


S100 has several different applications. Below are a few examples.

Tumour or cell type

S100 + or -



Langerhan cell Histiocytosis


Spindle cell melanoma