Table 2.

 Choice of tissue for quality control of PSA and PSAP immunohistochemistry

Tissue	Optimisation of antibody dilutions		External positive control
	UK laboratories N (%)	Non-UK laboratories N (%)	UK laboratories N (%)	Non-UK laboratories N (%)
Not indicated	11 (8%)	7 (8%)	5 (4%)	6 (7%)
None	0	2 (2%)	11 (8%)	6 (7%)
Benign prostate	84 (63%)	65 (75%)	82 (62%)	67 (77%)
Benign prostate + well differentiated PC	14 (11%)	4 (5%)	10 (8%)	2 (2%)
Well differentiated PC	15 (11%)	5 (6%)	20 (15%)	5 (6%)
Benign prostate + poorly differentiated PC	2 (2%)	1 (1%)	2 (2%)	0
Well differentiated PC + poorly differentiated PC	1 (1%)	0	1 (1%)	0
Poorly differentiated PC	2 (2%)	0	1 (1%)	0
Benign prostate + well differentiated PC + poorly differentiated PC	4 (3%)	3 (3%)	1 (1%)	1 (1%)

PC, prostate cancer; PSA, prostate specific antigen; PSAP, prostate specific acid phosphatase.