Is this skin diseased, or is it just dirty?

CASE

Two brothers, aged 9 and 7 years, were brought to our clinic by their mother. The boys had an unaesthetic dirty appearance to the skin on their trunks, arms, and legs of some months' duration. Physical examination of both boys disclosed brown-to-dark, velvety textured, hyperpigmented areas on the abdomen and umbilical region, with light scaling, and on the dorsal and volar aspects of the upper and lower limbs (Figure 1). The neck and dorsum were not involved.

The mother assured us that the boys were otherwise healthy, were not taking any medications or nutritional supplements, and maintained good hygiene, including daily showers with shampoos and soaps. She denied her consent to perform dermal scraping or punch biopsy on any lesional area. Skin examination with Wood's light disclosed no fluorescence.

DISCUSSION

The diagnosis was terra firma-forme dermatosis (TFFD). After reassuring the mother of the benign nature of the condition, we performed focal swabbing with isopropyl alcohol, which removed the pigmentation. No follow-up was needed for either patient.

TFFD is a benign condition of unknown origin. The name derives from the Latin expression terra firma, meaning “dry land,” thus implying a clinical picture of hyperkeratosis and hyperpigmentation in a typical appearance of dirty skin.

The dermatosis is characterized by localized or extensive, sometimes symmetrical, clear-cut areas of subtle brownto- black pigmentation. The neck and trunk are involved the most often, but the scalp, arms, back, legs, axillary, umbilical area, and pubic lines can also be affected. Palpable papillomatous plaques and focal light scaling may also be present, usually without any symptoms.¹

TFFD is quite common in clinical practice. In reported cases, TFFD manifests at a wide range of ages (4-72 years), with most patients being prepubertal children and adolescents. The incidence is the same in both sexes, and a familial predominance has not been reported.²

Comment The cause of TFFD is not clearly explained. Incomplete maturation of keratin squames, combined with retention of melanin and buildup and compaction of scales and dirt through initial inadequate cleansing may have a role in the pathophysiology of the condition.³

Acanthosis nigricans is prominent in axillae, folds of the neck, groin, and antecubital and popliteal surfaces. Gougerot-Carteaud syndrome is clinically characterized by brown hyperkeratotic papules and plaques arranged in a distinctive reticular pattern on the posterior and lateral neck and trunk, and in the intertriginous areas. Pityriasis versicolor, or tinea versicolor, is easily recognized as the affected area fluoresces a yellow color under a Wood's light. These diagnoses were ruled out when the dyspigmentation resolved with focal swabbing.

Cleansing with a cotton swab soaked with isopropyl alcohol is promptly both diagnostic and therapeutic, 70% ethyl alcohol and 2% salicylic acid lotion are also effective. Recrudescence of TFFD is reported as exceptional.⁴ JAAPA

Claudio Guarneri is Aggregate Professor of Dermatology and Venereology at the Department of Social Territorial Medicine, Section of Dermatology, University of Messina (Italy). Serafinella Patrizia Cannavò is Professor of Dermatology and Venereology at the same institution. They have indicated no relationships to disclose relating to the content of this article.

REFERENCES

1. Duncan WC, Tschen JA, Knox JM. Terra firma-forme dermatosis. Arch Dermatol. 1987;123(5):567-569.

2. O'Brien TJ, Hall AP. Terra firma-forme dermatosis. Australas J Dermatol. 1997;38(3):163-164.

3. Guarneri C, Guarneri F, Cannavò SP. Terra firma-forme dermatosis. Int J Dermatol. 2008;47(5):482-484.

4. Browning J, Rosen T. Terra firma-forme dermatosis revisited. Dermatol Online J. 2005;11(2):15.