A 32-year-old man presents with deteriorating thumbnails. He is in good health except for a long-standing seizure disorder that is controlled with phenytoin. He denies trauma to the nails.
Key point: This is classic pterygium—overgrowth of nailfold skin onto the nail bed instead of nail plate. This may be laterally located (as in this case case) or centrally located. Pterygium is associated with nail matrix lichen planus; trauma to the nail matrix; and a small number of drugs, including phenytoin.
Treatment: There is no effective treatment, as the condition reflects scarring destruction of the matrix such that skin overgrows the area where nail should have been located.
Note: Although the condition appears rather dramatic, it is generally asymptomatic.