PELLAGRA
PELLAGRA ICD-10: E52
• Pellagra arises from a diet deficient in niacin or tryptophan, or both. Tryptophan is converted in the body to niacin. A predominantly maize-based diet is usually implicated.
• Pellagra is characterized by the three Ds: dermatitis, diarrhea, and dementia. Skin changes are determined by exposure to sunlight and pressure.
• The disorder begins with a symmetric itching and erythema on the dorsa of the hands, neck, and face. Vesicles and bullae may erupt and break, so that crusting occurs and lesions become scaly (Fig. 15-18A). Later, skin becomes indurated, lichenified, rough, covered by dark scales and crusts; there are cracks and fissures and a sharp demarcation from normal skin (Fig. 15-18B).
• Distribution: dorsa of hands and fingers (“gauntlet”) (Fig. 15-18B), band-like around the neck (“Casal necklace”) (Fig. 15-18A), dorsa of feet up to malleoli with sparing of the heel, and butterfly region of the face.
• Diagnosis is verified by detection of decreased levels of urinary metabolites.
• 100 to 300 mg niacinamide orally plus other B vitamins lead to complete resolution.
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B
FIGURE 15-18 • Pellagra (A) Scaly crusted band-like plaque on the neck (“Casal necklace”). (B) “Gauntlet” of pellagra; indurated, lichenified, pigmented, and scaly skin on the dorsa of the hands. Note sharp demarcation to lower arm.