IMMUNOHISTOCHEMICAL DETECTION OF PROSTATE-SPECIFIC ANTIGEN

Immunohistochemical detection of prostate specific antigen (PSA) is an important adjunct for the pathologist. The primary diagnostic uses of PSA immunohistochemistry include: separation of prostatic adenocarcin omas from other primary adenocarcinomas located in the pelvis; determi nation of the site of origin of a metastatic adenocarcinoma; and deter mination of whether an adenocarcinoma in a distant organ represents a metastasis from a prostate primary, A variety of polyclonal and monocl onal antibodies are available which may be used to detect PSA in a var iety of specimens, including formalin-fixed, paraffin-embedded section s, PSA is strongly expressed in the cytoplasm of normal and hyperplast ic prostate glandular epithelium. Similarly, PSA expression is retaine d by the vast majority of prostatic adenocarcinomas, although the quan tity and quality of staining are decreased, In general, comparatively few extra prostatic tissues and neoplasms have been shown to express P SA, supporting the high specificity of this marker.