[Cutaneous hyperpigmentation secondary to vitamin B12 deficiency in an infant].

Cutaneous hyperpigmentation is a rare clinical feature of vitamin B12 (cobalamin) deficiency. The cause is unknown and there are different hypothesis about the pathogenesis of the hyperpigmentation. We report the case of an 8-month-old girl, with history of neuromadurative delay, hypotonia, anemia and neutropenia, who was referred to our Service by brownish hyperpigmentation on her hands and feet of 3 months of evolution. Based on the clinical suspicion of vitamin B12 deficiency, we performed a laboratory dosage that showed decreased levels of cobalamin, reason for which replacement therapy was indicated. It highlights the importance of the presumption of vitamin B12 deficiency as a cause of cutaneous hyperpigmentation and its rapid resolution after the establishment of the appropriate treatment.