A peculiar leg rash

A 57 year old woman had a four month history of a mildly painful rash on both legs and feet. The skin was extremely dry and rough, with small cracks and brownish flakes (figure). Her diet lacked fruit and vegetables and she consumed approximately 8 units of alcohol daily. The brown colouring made eczema unlikely. Pellagra was considered and later confirmed by a reduced serum vitamin B3 (niacin) level of 11 µmol/L (normal range: 20-50 µmol/L). Excess alcohol and poor niacin intake contributed to this patient’s condition. Alcohol affects niacin metabolism by inhibiting the conversion of tryptophan to niacin.1 Pellagra typically affects the neck and/or the back of the hands, but in this case only the legs were affected.

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