No--not fungus, bacteria, or cancer. Most likely, this is hyperpigmenation. Medical name:
chloasmaMelasma. Common name: "mask of pregnancy." Trouble is, most people who have it aren't pregnant and don't have any hormone changes.
Tretament is fairly straighforward. Most doctors use combinations of hydroquinone and Retin-A. Ask your dermatologist for diagnosis and treamtnet.
Best.
Dr. Rockoff