Stains & CD markers
Prostatic acid phosphatase (PAP, PSAP)
Copyright: 2002-2024, PathologyOutlines.com, Inc.
PubMed Search: Prostatic acid phosphatase [title] "loattrfree full text"[sb]
Prostatic acid phosphatase (PAP, PSAP)
Author: Nat Pernick, M.D.
Last author update: 1 April 2012
Last staff update: 18 June 2021
Copyright: 2002-2024, PathologyOutlines.com, Inc.
PubMed Search: Prostatic acid phosphatase [title] "loattrfree full text"[sb]
Table of Contents
Definition / general | Uses by pathologists | Microscopic (histologic) images | Positive staining - normal | Positive staining - disease | Negative stainingCite this page: Pernick N. Prostatic acid phosphatase (PAP). PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/stainsPAP.html. Accessed December 2nd, 2024.
Definition / general
- Prostatic acid phosphatase (PAP), also prostatic specific acid phosphatase (PSAP), is enzyme produced by prostate tissue
- Acid phosphatases release phosphate groups, optimally at acid pH
- May promote HIV infection
- Naturally occurring fragments form amyloid fibrils (Semen-derived Enhancer of Virus Infection), capture HIV virions and promote their attachment to target cells (Cell 2007;131:1059)
Uses by pathologists
- Identifies prostatic origin of metastases (whose primary is PAP+), including bone metastases (Ann NY Acad Sci 2011;1237)
- Differentiates between prostatic and urothelial carcinomas
- Differentiates between prostatic adenocarcinoma and mesonephric remnant hyperplasia (Ann Diagn Pathol 2009;13:402)
- Presence is presumptive test for semen in forensic studies
Microscopic (histologic) images
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Various tissues
Metastases, lymph node
Metastases, soft tissue
Prostatic adenocarcinoma
Prostatic adenocarcinoma
Prostate / colon in situ hybridization
Positive staining - normal
- Prostatic epithelium (lysosomal granules) and prostatic ducts
- May be expressed in non-prostatic tissue but at 1 - 2 orders of magnitude less than in prostate (Int J Clin Exp Pathol 2011;4:295)
Positive staining - disease
- Prostatic adenocarcinoma and duct carcinoma (considered more sensitive but less specific than PSA)
- PSA / PAP less sensitive in poorly differentiated adenocarcinoma (Am J Surg Pathol 1986;10:765, Am J Surg Pathol 1982;6:553)
- PSA / PAP may become negative after hormonal treatment (Hum Pathol 1996;27:1377)
- Bladder adenocarcinomas and rectal carcinomas may be strongly PAP+ but are PSA-
- Bladder cystitis cystica / cystitis glandularis is occasionally positive (Arch Pathol Lab Med 1988;112:734)
- Rectal carcinoids also positive for PAP, perhaps due to shared cloacal derivation of rectum and prostate (Am J Surg Pathol 1991;15:785); also ovarian strumal carcinoids
- Salivary gland: pleomorphic adenoma (50%), duct carcinoma (20%)
Negative staining
- Prostatic basal cells, urothelium, inflammatory cells
- Nephrogenic adenoma of prostate, bladder, kidney (usually, may be weakly positive)
- Mesonephric remnant hyperplasia (Ann Diagn Pathol 2009;13:402)
- Prostatic clear cell adenocarcinoma
- Nonprostate tissue and tumors other than those indicated above are usually negative / weak
