begins at the free edge and progresses proximally, causing a traumatic uplifting of the distal plate. Usually
incomplete, it results in white discoloration of the affected area, often complicated by secondary
microbial colonization. Typically traumatic, it may also result from any local problem that separates the plate
from the nail bed, such as periungual warts or onychomycosis. It also may originate from eczematous
or drug disorders, reactions to acrylic nails or nailhardeners, and psoriasis. The latter may at times occur
with complete separation of the nail, which is either mechanically lifted off the bed or separated by
traumatic bleeding. Absent local explanations, thyrotoxicosis must be ruled out (“Plummer’s nails”).
This may also cause brown nail discoloration.