Prostatic acid phosphatase (PAP)

Immunohistochemical expression

• apical cells of the prostatic acini (basal cells are negative) and, less strongly, in ducts: prostatic carcinoma

• seminal vesicle epithelium

• periurethral glands

• anal glands in men

• cloacal carcinomas:

  • transitional cell carcinomas of the bladder

  • periurethral gland carcinomas

  • colonic carcinomas

• neuroendocrine cells of the rectum and rectal carcinoids

• bladder urothelium

• renal tubular epithelium

• pancreatic islet cells and islet cell tumours

• hepatocytes

• gastric parietal cells

• mammary ductal epithelium

• pleomorphic adenoma and carcinomas of the salivary gland

• neutrophils

• teratomas

Rarely, pulmonary small cell carcinoma may produce ectopic prostate specific antigen and prostatic acid phosphatase2.

Diagnostic utility

• identification of metastatic adenocarcinoma of the prostate: use in conjunction with prostate specific antigen, CK7, CK20 (usual profile CK7-/CK20-) and CD 57.

• May help to differentiate intravascular large B-cell lymphoma from other lymphomas1

References

1 Seki, K., S. Miyakoshi, et al. (2004). "Prostatic acid phosphatase is a possible tumor marker for intravascular large B-cell lymphoma." Am J Surg Pathol 28(10): 1384-8.

2 Freeman NJ,Doolittle C. Elevated prostate markers in metastatic small cell carcinoma of unknown primary. Cancer 1991; 68:1118-20

©SMUHT/PW Bishop