[Terra firma-forme dermatosis].

Background: Terra firma-forme (i.e. resembling dry earth) is a condition chiefly affecting children wrongly considered as dermatosis arising out of negligence and inadequate corporal hygiene. It is in fact an acquired and asymptomatic grey-brown hyperpigmentation of the skin that persists despite normal washing with soap and water, but which subsides on rubbing with isopropyl alcohol 70%. Herein we report 10 new cases of this disorder.

Observations: Ten patients aged between 7 months in 17 years were seen for acquired macular skin pigmentation, either brown or grey, fragmented and confluent. In six patients, this abnormality was the main reason for the consultation, generally on aesthetic grounds, and more rarely for diagnosis or suspicion of acanthosis nigricans. In all cases, questioning revealed normal hygiene measures. The condition comprised macular or acquired papular pigmentation, either brown or grey, of bilateral and symmetrical disposition and electively affecting the neck, trunk and retro-malleolar area of the ankles. Clinical examination together with a test involving rubbing with isopropyl alcohol 70° confirmed the diagnosis, revealing healthy underlying skin.

Discussion: Terra firma-forme dermatosis is frequently seen in clinical practice but is largely ignored in the French literature, possibly because of relevant indifference towards the condition. It affects both sexes equally, with no predilection for age or ethnicity, although it is classically seen to a greater extent during adolescence. Diagnosis of the condition, which is easily made thanks to the hyperpigmentation of dirty brown appearance on the neck and the ankles in particular, should not mislead the practitioner into blaming patients for supposedly deficient body hygiene. Knowledge of this form of dermatosis is useful because of its potentially harmful aesthetic and social effects, despite the ease of treatment by insistent rubbing of the affected areas with medical alcohol or ether. Early recognition also avoids pointless additional investigations associated with differential diagnosis in relation to various other acquired or hereditary dermatoses involving brown or grey pigmentation.