1. A report creation support apparatus, comprising: a case report storage means for storing a plurality of different case images, each with a report text model associated therewith, the report text model being a text model derived from a report text of the corresponding case image by making at least certain words/phrases included therein changeable; a similar case image retrieval means for retrieving a case image which is similar to a diagnosis target image from the case images stored in the case report storage means; and a report creation means for creating a report text of the diagnosis target image by accepting input of a word/phrase appropriate for the diagnosis target image in a changeable word/phrase section of the report text model corresponding to the case image which is similar to the diagnosis target image retrieved by the similar case image retrieval means, wherein the report text model is generated by a report text model generating device including: lexical analysis means for performing lexical analysis on report text associated with the plurality of case images entered in free form text, dividing the text into words, checking the words with a medical dictionary to allocate meanings to the words, and extracting words/phrases describing features of the cases of the case images; and report text model generating means for generating report text models in which at least a portion of the extracted words/phrases that describe features of the cases of the case images are changeable; wherein the report creation means is a means comprising: a feature analysis means for analyzing a feature of a region of interest within the diagnosis target image; a word/phrase input means for accepting input of a word/phrase describing the analyzed feature to replace a word/phrase to be replaced therewith among the changeable words/phrases included in the report text model; wherein: the apparatus further comprises an extraction means for extracting a region of interest from the diagnosis target image; and the feature analysis means is a means for analyzing a feature of the extracted region of interest; wherein the extraction means is a means for accepting input specifying a single point on the diagnosis target image, and extracting a region of interest located around the single point, and wherein the region of interest is extracted by setting a discrimination region that sufficiently includes the region of interest, and by performing evaluation with respect to each pixel along straight lines that pass through each pixel within the discrimination region and a single point with regard to whether it represents an outline.