Pellagra From Tryptophan Depletion in Carcinoid Syndrome due to a Pulmonary Atypical Carcinoid Neuroendocrine Tumor.

Pellagra may complicate functioning pulmonary atypical carcinoid and present as a subtle acral dermatosis rather than the classical photo-distributed rash. In neuroendocrine tumor patients with chronic diarrhea and new skin changes, clinicians should suspect niacin deficiency and consider empiric nicotinamide, even when niacin assays are unavailable.