PSAP (Prostatic or Prostate Specific Acid Phosphatase) [PASE/4LJ]

Prostate Specific Acid Phosphatase (PSAP) is a 100 kD glycoprotein present in high concentration in the prostate gland and its secretions. PSAP is measured clinically because its level often rises in the serum in cases of prostatic carcinoma. By immunohistochemical analysis, PSAP has been found concentrated within the large secretory vacuoles of the supranuclear portion of the prostatic columnar epithelial cell. In hyperplastic prostates and in benign prostatic tissue adjacent to the prostatic carcinoma, PSAP activity is limited to the acinar or ductal columnar epithelial cells and adjacent luminal content. PSAP reactivity in an extraprostatic tumor is an accurate and sensitive indicator of metastatic prostatic carcinoma.