title: S-100 protein expression by primary and metastatic adenocarcinomas.
abstract: S-100 protein has been used as a marker of various lesions, including peripheral nerve sheath, cartilaginous and salivary gland tumors, chordomas, histiocytosis X, and melanomas, among others. The list of neoplasms that can express S-100 protein continues to expand. It has been suggested that staining for S-100 protein may be of aid in the differential diagnosis of amelanotic melanoma versus poorly differentiated tumors. Three hundred fifty primary and metastatic adenocarcinomas from various sites were immunostained for S-100 protein with the use of a commercially available polyclonal antibody. Forty-two percent of the adenocarcinomas tested expressed S-100 protein to varying degrees. The relative incidence of S-100-positive tumors varied with the primary sites, some expressing S-100 protein more often than others. A primary neoplasm able to express S-100 protein was usually associated with metastatic foci also expressing this marker. However, occasionally, a primary S-100-positive tumor was associated with metastasis that lacked expression of S-100. This study emphasizes the importance of testing for a panel of tumor markers in the evaluation of poorly differentiated tumors and cautions on possible difficulties that may arise in the interpretation of immunocytochemistry results.
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology / Q000556:secondary / Q000648:ultrastructure; D006801:Humans; D007633:Keratins / Q000378:metabolism; D008545:Melanoma / Q000378:metabolism; D009418:S100 Proteins / Q000378:metabolism*
chemical_list: D009418:S100 Proteins; D007633:Keratins