ABSTRACT
Dorsal pterygium or pterygium unguis results from a focal destruction of the nail matrix with subsequent scar formation. Because a nail plate is not formed at the affected site, the proximal nail fold epithelium attaches directly to the nail bed epithelium and both grow distally together to produce a wing-shaped deformity. Pterygium unguis usually affects the fingers and rarely the toes. It is the hallmark of severe lichen planus, although it is not specific. It can occur after trauma. Multiple pterium in the same nails have been described ( Figure 5.1 and 5.2 ).
