Take home message: B12 deficiency can lead to patchy hyperpigmentation of the skin, especially in people with darker skin tones
A new case study from Rajasthan, India, reports:
- 23 year old "strict vegetarian" woman
- with fatigue, dyspnea on exertion for 3 months
- severe pallor and darker pigmentation over the knuckles of both hands
- She had too little hemoglobin, and red blood cells that were too big (typical for B12 deficiency).
- Her serum B12 was only 59 ng/L
- She received B12 (cyanocobalamin) injections and iron tablets
- After 8 weeks the symptoms (blood parameters and skin pigmentation) returned to normal.
"About 10% of vitamin B12 deficient patients show reversible melanin skin pigmentation mainly affecting knuckle pads and oral mucosa. It is an under-recognized sign of megaloblastic anemia and should always be looked for in the setting of pallor."
Pannu AK: Knuckle pigmentation and vitamin B12 deficiency. QJM. 2017 Mar 17. doi: 10.1093/qjmed/hcx064 [Epub ahead of print]