Terra firma‐forme dermatosis: Differential diagnosis and response to salicylic acid therapy

Abstract

Terra firma-forme dermatosis (TFFD), first described by Duncan in 1987, is a relatively common but probably underdiagnosed condition, characterized by a reticular hyperpigmented dirtlike eruption resistant to washing with common soap but typically removed with rubbing with 70% isopropyl alcohol. We present a case of TFFD in an 8-year-old boy with rapid response to 5% salicylic acid in petrolatum ointment.

Dermoscopic patterns of terra firma-forme dermatosis

“…Hyperpigmented dirt-like papular lesions resistant to washing are the typical presentation of the disorder. There are a few case studies that have reported the dermoscopic features of TFFD and to the best of our knowledge, "polygonal plate-like brown scales arranged in a mosaic pattern" is the only pattern identified for the entity so far [1,3,4]. In this study we described two additional patterns including linear and curvi-linear structures (seborrheic keratosis-like pattern) and perifollicular hyperpigmentation.…”

“…In this study we described two additional patterns including linear and curvi-linear structures (seborrheic keratosis-like pattern) and perifollicular hyperpigmentation. Terra firma-forme dermatosis may strongly imitate many cutaneous conditions including dermatosis neglecta, acanthosis nigricans, confluent and reticulated papillomatosis, ashy dermatosis, pityriasis versicolor, friction melanosis, and macular amyloidosis [1,[5][6][7]. Dermatosis neglecta is the main entity in the differential diagnosis in which a clinical improvement is achieved after both alcohol swabbing and washing with water and soap [3].…”

“…Washing the lesional skin with water and soap is ineffective. The etiopathogenesis of TFFD is unknown but it is hypothesized that it may be associated with disordered, retained keratinization [1]. Dermoscopy is a non-invasive, in vivo diagnostic tool used in the diagnosis of many cutaneous conditions.…”

Terra firma‐forme dermatosis: a systematic review

“…The title and abstract of the 102 items were screened, and 69 were considered eligible for full‐text assessment. Of the 69 studies, 64 were included in the systematic review 1–63 . The studies were published between 1987 and 2020.…”

Study of sex predominance in skin disorders in children aged 1 month to 5 years

“…Most of the skin diseases were seen in the 1-5 years age (44.94%), followed by school children (29.6%) and infants (25.46%) [4]. Skin diseases in the pediatric age group can be transitory, chronic or recurrentand differ from those in adults in terms of diagnostic approach and management, while some of them manifest mainly or exclusively in children [5]. Socioeconomic status, external environment, climate exposure, dietary habits and different levels of functional development of skin are the more influential factors in skin disorders in children [6].…”