http://www.geographictonguehelp.com/art ... ctures.htm
Geographic tongue is one of the clear visible signs of vitamin B12 deficiency. When it was first spotted for me, it was diagnosed as a fungus. A second Dr in the same surgery diagnosed B12 deficiency and ordered the blood tests a week later.
The problem with my tongue was my first real "visible" indication of Pernicious Anaemia.