S100

Formalin-fixed, paraffin embedded tissue block or cell block, or 1 unstained charged slide for each test requested plus 3-4 additional unstained slides cut at 4 microns. Adequate space on each slide for control tissue is required.

S100 is a 20kDa acidic calcium binding protein, and is expressed in a variety of human tissues, including melanocytes, Langerhans cells, lipocytes, chondrocytes, Schwann cells, salivary and sweat glands, to name a few, and the corresponding tumors derived from these cells. It is most commonly used as a sensitive marker for malignant melanoma.