Last revised by Daniel J Bell on 04 Mar 2019

S100 is a family of cytoplasmic calcium-binding proteins expressed in numerous cell lines which can be targeted by immunohistochemistry. Staining for S100 is helpful in characterizing a number of tumors, including malignant melanoma, glial tumors, neurogenic tumors (e.g. schwannomas and neurofibromas), mesenchymal tumors (e.g. chondromas, chondrosarcomas, liposarcomas, some osteogenic sarcomas) and some histiocytic tumors 1,2

History and etymology

S100 is a contracture of 100% soluble in ammonium sulphate at neutral pH 3.

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