Some patients with vitiligo have an underlying autoimmune disease.
Autoimmune diseases associated with vitiligo:
(1) autoimmune polyendocrinopathy, especially when Addison's disease and/or Grave's disease are present
(2) rheumatoid arthritis
(3) psoriasis
(4) systemic lupus erythematosus
(5) pernicious anemia
Proposed mechanism: autoantibody targeting melanocytes.
Patients with autoimmune Addision's disease may have autoantibodies against aromatic L-amino acid decarboxylase or tryptophan hydroxylase.
Some affected families have a defect in the NALP1 gene on 17p13.
A skin biopsy may show a loss of dermal melanocytes in affected areas.
Differential diagnosis:
(1) depigmenting chemical exposures
(2) depigmentation due an underlying skin disease
