Dementia, diarrhea, desquamating shellac-like dermatitis revealing late-onset cobalamin C deficiency

We present a case of late-onset cobalamin C deficiency presenting with a unique shellac-like erosive desquamation and mental status changes that was dramatically responsive to treatment. We discuss cobalamin C deficiency and compare the cutaneous findings with other similar nutritional deficiency states. The brown shellac-like desquamation should prompt dermatologists to consider this diagnosis in the setting of a suspected nutritional deficiency.