The present invention relates to a method and a medical device (10) for diagnosing a diseased condition in tissue of a human or animal subject, wherein tissue electrical impedance measurements are employed. At least one set of data pre-processing rules (12a - 12d) are applied to impedance of a target tissue region and impedance of a reference tissue region (11), wherein the reference tissue region is located in close proximity to the target tissue region. The impedance data of the target tissue region and the impedance data of the reference tissue region comprises a plurality of impedance values measured in the target tissue region and the reference tissue region, respectively, wherein the tissue measurements in the two tissue regions are performed substantially concurrently or immediately consecutively. On the basis of the pre-processed data, a trained evaluation system algorithm (14) diagnoses the diseased condition in the target tissue region.
