Addisonian pigmentation and vitamin B₁₂ deficiency: a case series and review of the literature.

Skin changes associated with vitamin B₁₂ deficiency are common. In most cases, patients present primarily with systemic involvement (eg, megaloblastic anemia and/or neurologic effects), and additional cutaneous changes related to the diagnosis are noted as incidental findings. The role of vitamin B₁₂ deficiency in the etiology of Addisonian pigmentation has not been well studied. We discuss the importance of testing vitamin B₁₂ levels in patients who present for evaluation of generalized hyperpigmentation. Various cutaneous changes associated with vitamin B₁₂ deficiency also are reviewed.