Terra firma-forme dermatosis: A report of ten individuals with Duncan’s dirty dermatosis and literature review

BACKGROUND: Terra-firma forme dermatosis, also known as Duncan’s dirty dermatosis, is a benign skin condition that presents as dirt-like plaques in patients of all ages. PURPOSE: We describe a series of ten patients that presented with terra-firma forme dermatosis. METHODS AND MATERIALS: We reviewed PubMed for the following terms: dermatosis, Duncan’s dirty dermatosis, isopropyl alcohol, terra firma, and terra firma-forme dermatosis. We also reviewed papers containing these terms and their references. RESULTS: The diagnosis of terra firma-forme dermatosis was confirmed in all patients who had complete resolution of each lesion after the application of 70% isopropyl alcohol. CONCLUSIONS: Terra-firma forme dermatosis is easily diagnosed and treated with 70% isopropyl alcohol. It is important to recognize this benign dermatologic condition since it can be confused with other cutaneous disorders. Therefore, in order to avoid unnecessary referrals, biopsies, blood tests, and medications, we suggest a trial of wiping the skin lesion with 70% isopropyl alcohol pads when the diagnosis of terra-firma forme dermatosis is considered.