Pterygium inversum unguis: report of an extensive case with good therapeutic response to hydroxypropyl chitosan and review of the literature.

Pterygium inversum unguis is a rare but not exceptional dermatological condition, with few descriptions in literature. It occurs more frequently in females and may be associated with several clinical conditions. About 50% of cases are concurrent with collagen diseases such as systemic lupus erythematosus and scleroderma. Severe cases are accompanied by moderate morbidity caused by discomfort when the patient has to perform minor tasks. The treatment has been considered complex, regardless of its underlying cause, with poor response to the topical therapies such as keratolytics and corticosteroids. This paper reports a case of pterygium inversum unguis with a good therapeutic response to hydroxypropyl chitosan and includes a review of the literature.