CLSI MM04-A provides recommendations for the performance of immunocytochemical assays on cytologic and surgical pathology specimens. It is intended to promote a better understanding of the requirements, capabilities, and limitations of these diagnostic methods; to improve their intra- and inter-laboratory reproducibility; and to improve their positive and negative predictive values in the diagnosis of disease.

The U.S. Food and Drug Administration (FDA) has evaluated and recognized this approved-level consensus guideline for use in satisfying a regulatory requirement.