The mask of deficiency: A rare case of facial hyperpigmentation in vitamin B₁₂ deficiency – a case report and review of literature.

This article focuses on a rare presentation of vitamin B12 deficiency manifesting as hyperpigmentation over the face and oral cavity, which can mimic Addison's disease. Typically, vitamin B12 deficiency causes neurological symptoms and skin hyperpigmentation primarily on the hands and feet, but facial and oral involvement is uncommon. The case described involves a 56-year-old male with generalized facial and oral hyperpigmentation, diagnosed with pernicious anemia-related vitamin B12 deficiency despite not being vegetarian. The article emphasizes the importance of considering vitamin B12 deficiency in the differential diagnosis of facial hyperpigmentation once Addison's disease is excluded, highlighting that uncommon manifestations of common diseases warrant clinical attention.