The correct answer is eczema (choice “a”), a very common trigger
for fingernail dystrophy. Lichen planus (choice “b”) can
certainly cause nail dystrophy, onycholysis, or even
onychorrhexis, but the changes seen on this man’s nail were much
more uniform than those seen in lichen planus. The lack of
response to the most effective oral antifungal medication
available effectively ruled out onychomycosis (choice “c”). That
medication would have had no effect on a candidal infection
(choice “d”), either, but the lack of perionychial edema and
redness spoke rather loudly against that possibility in the
first place. Atopic dermatitis, in all its manifestations, is
seen many times every day in the average clinical dermatology
practice, and odds are that’s what was affecting this man’s
nail. Two possible mechanisms have been advanced to explain the
very common nail ridging and dystrophy seen in atopic patients.
One is the separation of dry, thin cuticle from the nail plate,
which exposes the matrix to environmental ins