P17 Photosensitive rashes in the context of alcoholism: a diagnosis to remember

Abstract

Abstract Pellagra is a disease defined by a deficiency in niacin and its precursor tryptophan. It is a clinical diagnosis characterized by the ‘four Ds’: dermatitis, dementia, diarrhoea and death (Badawy AA. Pellagra and alcoholism: a biochemical perspective. Alcohol 2014; 49:238–50; Pipili C. The diagnostic importance of photosensitivity dermatoses in chronic alcoholism. Dermatol Online J 2008; 14:15). It is predominantly a disease of non-Western countries with low niacin-containing diets, based on maize, with little meat or vegetables. In Western populations, the commonest causes of pellagra include alcoholism, gut malabsorption, some drugs and, rarely, carcinoid, which causes increased conversion of tryptophan to serotonin, depleting niacin precursor stores. The histopathological features of pellagra are nonspecific; however, pallor and keratinocyte ballooning in the upper third of the epidermis can be suggestive. We present two cases of pellagra in the context of alcoholism. Patient 1 was a 58-year-old woman who presented with a 6-week history of a rash on the dorsal hands which spread to the forearms and dorsum of both feet. Examination revealed a photodistributed erythematous rash with a prominent leading edge, wrinkling and hyperkeratosis. She described loss of appetite, diarrhoea and increasing confusion. A punch biopsy from the right forearm showed focal parakeratosis, perivascular inflammation and mild spongiosis with increased mucin in the superficial dermis. A clinical diagnosis of pellagra was suspected, and empirical niacin was prescribed. Patient 2 was a 60-year-old woman who presented with a 1-month history of a progressive itchy rash affecting her arms and legs. Examination revealed a striking photosensitive erythematous rash of her arms and legs, with complete sparing of the inner aspect of the arms. Skin biopsy showed mild keratosis, with subtle thickening of capillary walls. A diagnosis of pellagra was suspected and treatment with oral niacin commenced. Both patients drank alcohol to excess. Both had negative plasma porphyrins and had not started any new drugs and autoimmune screens were normal. The clinical appearance was identical in both cases. Patient 1 continued to drink excess alcohol, but the rash resolved with niacin supplementation. Patient 2 only took a short course of niacin due to significant flushing, but she managed to reduce her alcohol intake significantly and her rash fully resolved. Pellagra is a rare diagnosis in a Western population, but it is an important diagnosis to remember in patients presenting with a photosensitive rash, particularly in the context of alcohol abuse.