Differentiation of malign and benign tissue based on spectral information can be done by only using a small fractional amount of the original mid-infrared spectrum. An optimally selected arrangement of a few narrow-band quantum cascade lasers provides proficient signal-to-noise ratios and can drastically reduce the data acquisition time with constant discriminability, such that real-time applications will be possible in short-term and in-vivo diagnostics in the long-term.