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.