Dermatologic Manifestations of Pellagra Workup

Updated: May 13, 2022
  • Author: Vladimir Hegyi, MD, PhD; Chief Editor: Dirk M Elston, MD  more...
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Laboratory Studies

The therapeutic response to niacin in a patient with the typical symptoms and signs of pellagra establishes the diagnosis.

Blood counts (anemia), findings of hypoproteinemia, higher levels of serum calcium and lower levels of serum kalium and phosphorus, liver function test results, and serum porphyrin levels can help in diagnosing pellagra.

Low serum niacin, tryptophan, NAD, and NADP levels can reflect niacin deficiency and confirm the diagnosis of pellagra.

Low urinary levels of N- methylnicotinamide and pyridone suggest niacin deficiency and support the diagnosis of pellagra. The combined excretion of N- methylnicotinamide and pyridone of less than 1.5 mg in 24 hours indicates severe niacin deficiency.


Histologic Findings

Nonspecific dermatitic changes are usually evident. Early changes include a perivascular lymphohistologic infiltrate in the upper dermis, with mild edema in the papillary dermis; dilatation of capillaries; and, later, dermal fibrosis. Epidermal changes include early subcorneal blisters; pallor of the upper epidermis; and, later, hyperkeratosis, parakeratosis, and epidermal atrophy. In recurrences in the same site, blisters (pemphigus pellagrosus) contain lymphocytes, neutrophils, and histiocytes.