to the editor: The "Photo Quiz"1 in the January 1, 2005, issue of American Family Physician was a nice quiz about an uncommonly diagnosed condition: lichen nitidus. I would like to add to the discussion of the differential diagnosis. Lichen nitidus is one of only a few skin conditions that exhibit the Koebner phenomenon. Other skin conditions that exhibit the Koebner phenomenon are: juvenile rheumatoid arthritis (systemic form),2 lichen planus, molluscum contagiosum, pityriasis lichenoides et varioliformis acuta,3 psoriasis, vitiligo,4 and warts.
Asking the patient about areas of trauma, and then looking for clustered or linear distribution of isomorphic lesions may be a major clue in the diagnosis of these disorders.
Thank you for an interesting discussion.