Marchiafava-Bignami Disease and Pellagra in a Chronic Alcohol User: A Reversible Case of Cognitive Impairment.

Marchiafava-Bignami disease (MBD) is a rare complication of chronic alcoholism characterized by demyelination of the corpus callosum. Pellagra, resulting from niacin (vitamin B3) deficiency, typically presents with dermatitis, diarrhea, and dementia. Both MBD and pellagra are often associated with severe nutritional deficiencies. We describe the case of a 56-year-old man with alcohol use disorder admitted after a syncopal episode, presenting with disorientation, apathy, and photosensitive desquamative lesions on sun-exposed skin. Brain MRI revealed T2 hyperintensity in the splenium and body of the corpus callosum, compatible with subacute MBS. Laboratory tests confirmed niacin deficiency, establishing concomitant pellagra. The patient received B-complex vitamin supplementation and was maintained in alcohol abstinence. His cognitive and dermatologic condition improved markedly, with near-complete recovery after six months. This case underlines the importance of recognizing nutritional deficiencies in alcohol-related neuropsychiatric presentations.