Terra Firma-Forme Dermatosis: It’s Easy When You Know It

Background: Terra firma-forme dermatosis, also called “Duncan’s dirty dermatosis” is an acquired, benign and asymptomatic condition characterized by a disorder of keratinization. It’s usually presented as a brownish-black, dirt-like plaques, in patients with normal hygiene. The lesions often affect the neck, ankles, trunk and face. This condition is most frequently seen in children and adolescents but doesn’t have a predilection for any gender and is also unrelated to any known genetic condition or familial inheritance.

Objective: Raise awareness amongst pediatricians for an early diagnosis of this condition, as it could save children from unnecessary investigations and treatments.

Case Presentation: A 16-year-old adolescent girl with a personal history of type I tuberous sclerosis and epilepsy presented at her regular pediatric consultation for her annual follow-up with an asymptomatic brownish dirt-like lesion at the anterior region of the thorax with some weeks of evolution. Both the patient and her mother thought the lesion was dirt and tried to clean it by rubbing it with water and soap without success. There was no history of an inflammatory dermatosis in the area or other dermatologic conditions before this. There was also no history of bad hygiene habits. At the consultation, rubbing the lesion with an 70% isopropyl alcohol-soaked gauze pad and applying pressure resulted in complete disappearance of the lesion, therefore, the diagnosis of terra firma-forme dermatosis was confirmed. After this consultation the adolescent girl manifested frequent recurrences of the lesions, mostly in both her arms, which always disappear after she applies an alcohol-like solution.

Conclusion: Both diagnosis and treatment of Terra firma-forme dermatosis consists in the application of 70% isopropyl alcohol. It’s important to recognize this condition and not confuse this benign and easily treatable condition with other dermatologic disorders in order to avoid unnecessary exams and medications.