Pellagra, secondary to a deficiency of niacin, is manifested clinically by dermatitis, diarrhea, and dementia.
The dermatitis is most prominent in sunlight exposed skin and consists of a spectrum from mid-brown facial papules, to well demarcated patches on the neck, Casal's necklace.
Patients with carcinoid tumors can develop pellagra, as can those with Hartnup's disease.
Isoniazid and 5-fluorouracil can precipitate pellagra.
- Niacin 100 mg daily.