Back to real hardcore diagnosis:
Case 1: A soldier returning from Afghanistan presents with the skin lesion shown below.
Case 2: A photographer who travels worldwide presents with subacute insidious fatigue, malaise, fever, and weight loss over months. The spleen is markedly enlarged but minimally tender. Labs show a severe anemia. The patient notes his skin has "darkened" over the last few months. Without treatment, this disease is lethal. Bone marrow aspirate is shown below.
First image is in the public domain; the second image is shown under Creative Commons Attribution Share-Alike License.