Terra firma‐forme dermatosis

A 9‐year‐old boy was brought by his mother to our department for a follow‐up visit and dermoscopy of melanocytic nevi. During the consultation, she complained of a gradually increasing, asymptomatic, cutaneous discoloration involving the trunk, arms, and lower limbs of her son which had appeared approximately at the end of the summer.  The boy was healthy and was not taking any medication or nutritional supplements. Despite good hygiene, including showers and brushings with acid liquid soap at least three to four times per week, he showed no improvement of the condition.  Physical examination revealed dirty‐appearing skin, composed of subtle, but clear‐cut, brown to blackish areas with a velvety texture, symmetrically involving the lateral sides of the trunk, umbilical, and periumbilical regions with light scaling, dorsal and volar surfaces of the arms, and posterior parts of the lower limbs ( Figs 1 and 2). The neck, dorsum and anterior aspects of the lower limbs were uninvolved. 1Diffuse brown–blackish hyperpigmentation of the lateral aspect of the trunk and of the dorsal surface of the arm2Subtle pigmentation of the abdomen  Partial removal of these patches by isopropyl alcohol swabbing ( Fig. 3) confirmed the clinical suspicion of terra firma‐forme dermatosis. The boy's mother refused our proposal of dermal scraping and 3‐mm punch biopsy when reassured about the benign nature of the condition and the ease of treatment. 3Alcohol swabbing reveals a pink linear area of normal skin. The appearance of the alcohol pad after rubbing  The patient was seen 24 h later for erythema and burning of lesional areas because of excessively vigorous and extensive rubbing, but with no residual signs of the disease ( Fig. 4). 4Absence of dermatosis after cleansing at home. Notice frictional erythema of the treated areas