In the latest Clinical Problem-Solving article, a 47-year-old homeless man presented to the emergency department with intermittent pain and a pins-and-needles sensation in his legs. One month earlier, paresthesias had developed in his toes, which spread gradually to his shins.
Pellagra (or “rough skin,” from the Italian pelle agra) is rare in the United States, but it remains an important problem in developing countries. This condition results from inadequate dietary intake of niacin and is characterized by “the four Ds”: diarrhea, dermatitis, dementia, and death.
• What conditions or medications are associated with pellagra?
Pellagra may develop owing to malnutrition, food faddism, alcohol abuse, or medications such as isoniazid, pyrazinamide, fluorouracil, azathioprine, chloramphenicol, and ethionamide. In patients with HIV infection, pellagra-like manifestations such as dermatitis, diarrhea, and dementia can develop.
• Describe the dermatitis associated with pellagra.
The dermatitis of pellagra involves sun-exposed skin in a bilateral and symmetric pattern. The characteristic and prominent eruption can occur on the dorsum of the hands, the V-area of the neck, the face, and exposed skin on the legs and feet. The rash may resemble a sunburn with erythema, or it may be characterized by hyperpigmentation, thickening, dryness, and roughness. Pain may also develop owing to fissures and excessive dryness. One of the hallmark clinical signs is an eruption on the front of the neck extending into the region of cervical dermatomes C3 and C4, simulating a necklace (Casal’s necklace).
Morning Report Questions
Q: What are some additional clinical features of pellagra?
A: Patients with pellagra can have a wide range of neuropsychiatric manifestations, such as irritability, anxiety, delusions, hallucinations, apathy, spastic paresis, fatigue, depression, myelitis, and peripheral neuropathy of the upper and lower extremities. Approximately half the patients with pellagra have gastrointestinal manifestations. Diffuse inflammation and atrophy of the mucosal surface of the gastrointestinal tract results in diarrhea. Anorexia and malabsorptive diarrhea lead to malnutrition and eventual cachexia.
Q: Is pellagra easy to recognize?
A: Although pellagra is a prototypical nutritional deficiency with a well-defined tetrad of clinical manifestations, it is not always easily recognized. The classic symptoms and signs of niacin deficiency typically evolve at different intervals over time, rather than appearing simultaneously, making it harder for the clinician to see the pattern.