iCon-TMA for control and quantitation of immunohistochemistry and in situ molecular pathology analysis

Reliable assessment of in situ pathology analyses like immunohistochemistry, RNA in situ hybridization, and FISH are critically important in diagnosis and treatment decisions. We describe the development of small tissue microarrays (TMA) for the internal control and quantitation of these techniques, the iCon-TMA. In its simple variant, these iCon-TMA (abbreviated from internal control TMA) consist of 2 tissue cylinders, one being clearly positive and the other clearly negative for a specific marker. In its more elaborate format, the iCon-TMAs carry additional tissue spots providing a scale for quantitatively assessable markers, e.g. representing scores of negative, weak, moderate, or strong positivity. The specimen with the yet unknown reactivity is then applied to the iCon-TMA section, and both are simultaneously processed and analyzed, thus providing a convenient measure for in situ quality control and quantitation.