Role of antibody to S100 protein in diagnostic pathology

Normal tissues and various tumors were examined for S100 protein, using anti-S100 protein antiserum, in an immunoperoxidase reaction. Among normal tissues, in addition to the previously reported presence of S100 protein in some neurons, glial, and Schwann cells of the nervous system, melanocytes and Langerhans cells of the skin, interdigitating reticulum cells of lymph nodes, and chondrocytes, we demonstrated it in myoepithelial cells and ducts of sweat glands, salivary glands, and the breast, serous glands of the lung, fetal neuroblasts, and sustentacular cells of the adrenal medulla. Among neoplasms, S100 protein previously has been reported in neurogenic tumors, melanomas, and neuroblastomas; we have demonstrated it in mixed sweat gland tumors, histiocytosis X, pleomorphic adenomas of the salivary gland, medullary carcinomas of the breast, bronchioloalveolar carcinomas of the lung, sustentacular cells of pheochromocytomas, teratomas of the ovary, and tumors of cartilage (enchondromas, osteochondromas, and chondrosarcomas). With S100 protein producing tumors, a normal progenitor cell was identified, indicating that demonstration of S100 protein in tumors confirmed their origin.