1. An information processing apparatus comprising: an input unit that inputs a plurality of first regions selected as diagnosis targets from a tissue sample image obtained by capturing a tissue, a plurality of second regions selected as diagnosis targets from the tissue sample image, and pieces of position information of the respective regions selected on the tissue sample image; and a calculator that calculates a similarity between the plurality of first regions and the plurality of second regions, based on correlations considering distances between the selected regions on the tissue sample image.