You can find sample case studies using Google by searching for your disease and "case study". To insure that you are using a reliable source:
Google Images will aid you in finding images for your presentations. Remember that you need to cite where you found the image.
You can also find books and articles using Google Scholar.
MedlinePlus
Merck Manual
Medscape Reference (emedicine) Includes presentation, differential diagnosis, and blood work
ARUPconsult Laboratory test selection tool or find information on hematologic diseases
Lab Tests Online Find information on tests or diseases/conditions