Diagnostic Sign of Terra Firma-Forme Dermatosis

Background: Terra Firma-Forme Dermatosis (TFFD), a benign skin condition which presents with asymptomatic brown to black plaques which resemble dirty skin. Aim: To document a new case presentation with TFFD in the Arab region which is considered as one of the differential diagnoses of dirty neck. Case presentation: A 15-year-old girl presented with a history of asymptomatic brownish dirt-like lesion on the nape and sides of the neck for 4-years duration, not resolved by wash with water and soap and confused with other dermatoses like acanthosis nigricans or atopic dermatitis. The diagnosis of TFFD was confirmed when the lesions were completely resolved after gentle swabbing with 70% isopropyl alcohol. Conclusion: TFFD is rarely reported in Arab region and should be considered when evaluating cases of dirty neck-like presentation of atopic dermatitis or acanthosis nigricans.