pterygium inversum unguis pterygium inversum unguis pterygium inversum unguis or ventral pterygium is characterized by the adherence of the distal portion of the nailbed to the ventral surface of the nail plate.: 788 the condition may be present at birth or acquired, and may cause pain with manipulation of small objects, typing, and close manicuring of the nail.: 788 secondary due to connective tissue disorders pterygium inversum unguisother namespterygium inversus unguis, and ventral pterygium: 660 specialtydermatology