FTIR based spectral histopathology was used for label-free classification of tumor tissue sections. The regions of interest were identified and annotated with high spatial resolution. The spatial information was used for automated laser capture microdissection of relevant tissue areas. Subsequently, the collected tissue samples were analyzed using quantitative proteomics. This novel approach for precise sample collection in clinical studies was applied to differentiate epitheloid and sarcomatoid subtypes of diffuse malignant mesothelioma.