The characterisation of the early molecular genetic events of tumor development depends on the selective procurement of histopathologically defined small cell populations from premalignant tissue. In order to obtain high-quality DNA, mRNA and proteins from these small tissue samples and even from single cells, tissue microdissection is one of the most useful techniques, becoming increasingly important for molecular pathologists. Using different microdissection techniques which allow the

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... n of morphologically defined cell populations under direct visualisation, it is now feasible to study molecular genetic events that drive the multistep evolution in tumours. This review aims to present the current techniques of tissue microdissection and these techniques are discussed in the light of their ability to isolate premalignant cell populations in particular. Furthermore, we describe the subsequent application of several multiplex molecular analyses for characterising the microdis-sected premalignant cells. Applying these advanced techniques, alterations in the cellular DNA or the fluctuation of expressed genes that correlate with a particular stage of carcinogenesis can ultimately be compared within or between individual patients. Thus, these new technologies will have an enormous impact on molecular pathology with several diagnostic, prognostic and therapeutic implications.