[Histonet] validation

[Tony Henwood (SCHN)]

Immunohistochemistry validation is much more than simply 20 positives and 20 negative cases, though this will allow you to meet most accreditation requirements.

Validation is a multi step process:
1.	Optimisation: following a thorough literature review (what should and should not stain, clones used (any difference), recommended assay conditions (eg antigen retrieval type), choose an appropriate control to confirm staining conditions and perform an optimum titre.
2.	Validation: based on the literature review, choose appropriate known (or expected) positives and negative cases that the pathologists would entertain in the differential diagnosis that should be negative.

Take Prostate Specific Antigen as an example, include known prostatic carcinomas with a mix of well, moderately and poorly differentiated prostatic carcinomas and include negative tumours that should not express PSA (eg melanomas, lymphomas, colonic and lung carcinomas).

This is a scientific approach that inspires confidence in the usefulness of the test.

3.	Another task that we find extremely useful is on-going Verification, where we compare staining results with final diagnosis of cases immunostained for the marker.

Food for thought?

Regards 
Tony Henwood JP, MSc, BAppSc, GradDipSysAnalys, CT(ASC), FFSc(RCPA) 
Principal Scientist, the Children's Hospital at Westmead
Adjunct Fellow, School of Medicine, University of Western Sydney 
Tel: 612 9845 3306 
Fax: 612 9845 3318 
Pathology Department
the children's hospital at westmead
Cnr Hawkesbury Road and Hainsworth Street, Westmead
Locked Bag 4001, Westmead NSW 2145, AUSTRALIA 

-----Original Message-----
From: Nancy Schmitt via Histonet [mailto:histonet at lists.utsouthwestern.edu] 
Sent: Wednesday, 25 October 2017 4:16 AM
To: 'histonet at lists.utsouthwestern.edu'
Subject: [Histonet] validation

Good Day!
When performing validation on IHC, we use 20 positives and 20 negative cases.

When testing for negative, can the normal tissue surrounding the tumor be counted as negative?

Does the negative tissue need to be tumor that is negative for the AB or just normal tissue?

Thank you for your consideration,

Nancy
Dubuque, IA
Ph. 563-589-9810



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