Immunohistochemical study of S-100 protein and neuron specific enolase (NSE) in melanocytes and the related tumors.

Normal human skin, malignant melanoma, nevocellular nevus, blue nevus, nevus of Ota and mongolian spot were immunohistochemically investigated on the localization of S-100 protein and neuron specific enolase (NSE). Tissues were fixed with buffered-formalin, processed with routine procedure and examined by the ABC technique. All cases of malignant melanoma and nevocellular nevus showed a relatively high amount of S-100 protein, but NSE was scantly demonstrated on about the half cases of these tumors. Blue nevus, nevus of Ota and mongolian spot revealed the presence of a small amount of S-100 protein and NSE on the half cases. Normal melanocytes were devoid of S-100 protein and NSE. Our results suggest that S-100 protein is the useful marker for diagnosis of malignant melanoma, and immunoreactive intensity for S-100 protein represents the differentiation of neural crest derived melanogenic cells and tumors.