How does a pterygium differ from pterygium inversus unguium?
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| Fig. 68.5 Lack of distal separation in a patient with scleroderma
and pterygium inversus unguium. (Courtesy of James E.
Fitzpatrick, MD.) |
A pterygium, which is Greek for “wing,” is classically associated with lichen planus. Lichen planus attacks the
nail-forming unit, the matrix, and causes permanent scarring. Because the nail plate at that site is no longer made, the
proximal nail fold attaches to the nail bed directly,
and both grow out distally. This produces the
“winglike” appearance.
Pterygium inversus unguium occurs when
the nail plate distally does not separate from the
underlying digital bed skin. The fingertip ulcerations
and scarring also seen in scleroderma contribute to
the inability of the nail to separate (Fig. 68-5). |
