16 citations,
October 2007 in “PubMed” Vitamin B12 deficiency can cause skin darkening and white hair, but it's reversible.
2 citations,
October 2016 in “Nutrition in clinical practice” Vitamin B12 deficiency can cause facial dark spots that go away with treatment.
13 citations,
June 2010 in “Journal of The American Academy of Dermatology” A man with Cronkhite-Canada syndrome had all 20 nails detach but improved with treatment.
9 citations,
June 2017 in “The American journal of dermatopathology/American journal of dermatopathology” The study found increased skin pigmentation and variable melanocyte density in a patient with Addison's disease.
5 citations,
June 2014 in “Gastroenterology report” Cronkhite-Canada syndrome can sometimes show unusual colonic adenomatous polyps.