pellagra is a nutritional disorder caused by niacin ( vitamin b3 ) deficiency , which leads to systemic disease with clinical manifestations from the skin , gastrointestinal tract and the nervous system . niacin forms into nicotinic acid and nicotinamide , which serve as precursors of two important coenzymes of cellular metabolism , namely nicotinamide adenine dinucleotide ( nad ) and nad - phosphate . the term pellagra - from pelle agra , italian for rough skin - was first used by frappoli in 1771 due to its dermatologic manifestations . however , since goldberger implicated vitamin b deficiency as the cause of pellagra in 1926 , the pellagra syndrome has historically been characterized by the 4 d s : dermatitis , diarrhea , and dementia leading to death . pellagra was a major widespread cause of death until the early 20 century , but fortification of flour with niacin has led practically to its eradication in developed countries . a 50-year old man was brought to the emergency department due to disturbed mental status . the patient was reported to be homeless , but no other information about his medical status or living conditions was available . the patient was unreliable in providing history of alcohol abuse or describing symptoms like fever in his recent past . clinical examination revealed normal vital signs , cachexia and dehydration , accompanied by extensive pigmentation and scaling eruptions on a red basis along the dorsa of his hands and the sun - exposed surface of his arms ( figure 1 ) . the patient was confused and disorientated but responded sufficiently to simple commands . laboratory investigation showed mild elevation of total white blood cell count , slightly elevated creatinine and low serum albumin . the remaining of the routine laboratory tests , including glucose , electrolytes and aminotransferases , were found within normal range . clinical follow - up did not reveal fever or other symptoms or signs indicative of an underlying infection . the patient was subjected to computed tomography imaging which excluded any brain or other pathology . following neurological assessment and the negative imaging studies , furthermore , as the characteristic skin lesions in an obviously malnourished homeless man were compatible with pellagra , pellagrous encephalopathy was the preferable diagnosis . although serologic and urinary assays confirming niacin deficiency were unavailable in our hospital , treatment with nicotinamide 300 mg orally in a daily basis was started . eighteen days later the patient died due to hospital - acquired pneumonia , without showing any remarkable improvement in his mental status . patients with pellagra have a brown discoloration of the skin , especially in sun - exposed areas . in advanced stages , the characteristic skin rash has a typical photosensitive distribution with welldefined borders , and is mostly observed on the face , the neck - forming the so - called casal s necklace - , the dorsa of the hands and the extensor surface of the forearms . in addition to skin changes , gastrointestinal involvement may lead to intractable diarrhea , stomatitis and glossitis , while the neurocognitive impairment - pellagrous encephalopathy - may present as apathy , memory loss , disorientation , depression or delirium . niacin deficiency should especially be suspected in the following conditions : i ) malnutrition ( homelessness , anorexia nervosa or severe comorbid conditions like end - stage malignancy or hiv ) ; ii ) malabsorption ( e.g. crohn s or hartnup disease ) ; iii ) chronic alcoholism ; iv ) hemodialysis or peritoneal dialysis ; v ) drugs like isoniazid , ethionamide , 6-mercaptopurine and estrogens ; vi ) carcinoid syndrome ( due to excess turnover of tryptophan , precursor of niacin , to serotonin ) . the characteristic - if not pathognomonic - skin lesions support its diagnosis on solely clinical grounds . clinicians should keep a high index of suspicion , in certain patient groups , in order to early diagnose and cure this potentially fatal but treatable disease .
we report a case of a 50-year old homeless male who presented with pellagra and pellagrous encephalopathy . the characteristic - if not pathognomonic - skin lesions of pellagra support its diagnosis on solely clinical grounds 
 . clinicians should keep a high index of suspicion , in certain patient groups , in order to early diagnose and cure this potentially fatal but treatable disease .