Terra firma-forme dermatosis (TFFD), also known as Duncan’s dirty dermatosis, is an idiopathic benign skin disease resulting from an altered keratinocyte maturation process. It is mostly reported in children and is characterized by asymptomatic brown to black stuck-on appearing patches, mimicking dirty skin, arranged with a reticulated pattern and scattered islands of normal skin. Elective locations of lesions are flexural areas and skin folds. The complete clearance of TFFD lesions after rubbing of 70% isopropyl alcohol (pathognomonic sign) is useful to confirm diagnosis that is usually clinical. Dermatoscopy typically shows large polygonal platelike brown scales arranged in a mosaic or cobblestone pattern. These features histopathologically correlate with compact lamellar orthohyperkeratosis and intracorneal orthokeratotic whorls with the underlying papillomatosis, irregular acanthosis, and basal layer hypermelanosis.