PSA or Prostate Specific Antigen is found in prosate tissue and in the majority of prosate carcinomas. PSA can be used to identify tumours origin, whether it originated in the prostate. The staining is seen in the acinar and ductal cells of prostate tissue.

The staining pattern of PSA is Cytoplasmic as shown below.

Picture 1 – PSA positivity in Prostate

 

PSA has several different applications. Below are a few examples.

Tumour or cell type	PSA + or -
Prostate Tissue	Positive
Prostate Carcinoma	Positive
Lung Carcinoma	Negative
Breast carcinoma	Negative