Pellagra is found worldwide but is more common in developing countries where poverty and malnutrition are more common (in part because the staple grains are not fortified with niacin). In addition to the skin, the neurologic system and gastrointestinal system are involved. Skin eruption tends to be photodistributed, symmetric, and erythematous. It may be accompanied by pain or itch. Various neurologic and gastrointestinal complaints such as dizziness, tremors, insomnia, fatigue, mood symptoms, nausea, vomiting, and diarrhea can be present and may precede skin manifestations.
The most common etiologies of pellagra are alcohol use disorder, various medications, inadequate intake, and malabsorption. Risk factors include poverty, staple diet that is poor in niacin (maize, Indian millet, or jowar), eating disorders, human immunodeficiency virus (HIV), alcohol abuse, medication (isoniazid, pyrazinamide, carbamazepine, carbidopa, chloramphenicol, phenytoin, phenobarbital), chemotherapy (5-fluorouracil, 6-mercaptopurine, azathioprine), post-surgical complications (gastrectomy), carcinoid syndrome (tryptophan is converted to serotonin instead of niacin), malabsorptive states (eg, Crohn disease, Hartnup disease), and hypothyroidism.
Symptoms of niacin or tryptophan deficiency take months to develop due to large tissue stores. Death due to multiorgan failure will occur in 4-5 years if left untreated.
E52 – Niacin deficiency [pellagra]
418186002 – Pellagra
Differential Diagnosis & Pitfalls
- Drug-induced photosensitivity
- Phytophotodermatitis occurs in the area of contact with the plant material / extract and is usually linear or drop-like in shape.
- Photoallergic dermatitis (see drug-induced photoallergic reaction)
- Phototoxic dermatosis (see drug-induced phototoxic reaction)
- Kwashiorkor often involves the hair and nails while pellagra spares these areas.
- The lesions of zinc deficiency (acquired, hereditary) are perioral and perineal but may resemble wet pellagra.
- Variegate porphyria
- Atopic dermatitis
- Systemic lupus erythematosus
- Juvenile dermatomyositis
- Trauma (eg, burns)
- Autoimmune bullous disease
- The lesions from glucagonoma are found on truncal areas, whereas lesions of pellagra occur on sun-exposed areas.
- Porphyria cutanea tarda
- Dermatomyositis may have a neck lesion but will also have a periorbital heliotrope (purple) rash and atrophic dermal papules of dermatomyositis (formerly called Gottron papules) on the fingers.
Drug Reaction Data