Dermatosis neglecta, or terra firma-forme dermatosis, is a clinical entity whose etiology has still not been fully defined. It is characterized by the presence of asymptomatic, dirtlike hyperpigmented plaques with a slightly papillomatous surface; these plaques cannot be removed with ordinary cleansing but disappear completely on swabbing with 70% ethyl or isopropyl alcohol. We report a new case of this entity.

The patient was a 10-year-old girl with no relevant past medical history. Her mother brought her to our unit for assessment of a persistent asymptomatic skin rash that had appeared several months earlier. Physical examination revealed brownish, reticulated, macular areas that were slightly papillomatous to the touch in some zones. The lesions were distributed symmetrically on the anterior aspect of the trunk, shoulders, and base of the neck (Fig. 1). Dermoscopy revealed no melanocytic pattern and no vascular abnormalities, but there were polygonal areas of brownish pigmentation that followed a linear pattern in some places and spared the natural folds of the skin (Fig. 2).

Figure 1.

Clinical appearance of the lesions.

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Figure 2.

Dermatoscopy image obtained using a digital contact dermatoscope with immersion fluid.

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Given the distribution and appearance of the lesions, swabbing with a cotton ball soaked in 70% ethyl alcohol was performed as a diagnostic test that doubles as treatment. This procedure cleared the lesions, revealing skin of a normal appearance in the treated area (Fig. 3). We established a diagnosis of dermatosis neglecta and instructed the patient to apply an exfoliant cream containing keratolytic agents (silica granules, salicylic acid, triclosan, aluminum oxide, and zinc oxide) and then wash the affected areas in order to accelerate the healing and complete resolution of the lesions.

Figure 3.

Clinical appearance of the lesions after swabbing with a cotton ball soaked in 70% ethyl alcohol.

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Terra firma-forme dermatosis is much more common than the literature would lead one to believe. It was first described by Duncan et al.,1 who reported cases from the 1970s and gave the condition its Latinate name for its earthy or dirtlike appearance. The cause of terra firma-forme dermatosis is not yet fully understood. It is believed that the lesions arise as a consequence of a delay in the maturation of keratinocytes, with melanin retention, and a sustained accumulation of sebum, sweat, corneocytes, and microorganisms in regions in which hygiene measures are less rigorous (e.g. neck, trunk, navel, and flanks), leading to insufficient exfoliation and the formation of a highly adhesive, compact dirt crust.2,3 This hypothesis is supported by the fact that these lesions have also been seen in painful areas—in particular hyperesthetic ones—that many patients avoid touching during their hygiene routines (hence the name dermatosis neglecta).4

Terra firma-forme dermatosis and dermatosis neglecta are widely considered to be synonymous, but some authors have proposed a separation of the terms. Although isolated cases of terra firma-forme dermatosis have been reported in infants, it occurs mainly in older children and adolescents with characteristic hygiene habits and with a distinctive distribution of the lesions,5 whereas dermatosis neglecta affects patients of any age whose hygiene in specific areas is insufficient.6

The differential diagnosis of the condition, which has a varied clinical presentation, should include confluent and reticulated papillomatosis of Gougerot and Carteaud (which, in exceptional cases, may partially respond to alcohol swabbing),7 pityriasis versicolor, acanthosis nigricans, pseudoacanthosis nigricans, psoriasis,8 dermatitis artefacta, some forms of ichthyosis, and, in certain localized cases, seborrheic keratoses and epidermal nevi.1,9

Most cases of dermatosis neglecta can be diagnosed without performing tests other than the alcohol swab test. If performed, histopathologic studies—reported in the literature in just 8 patients to date—generally show epidermal acanthosis and papillomatosis as well as prominent lamellar hyperkeratosis with orthokeratotic whorls. The histopathologic differential diagnosis of dermatosis neglecta must therefore include benign papillomatous entities such as confluent and reticulated papillomatosis, acrokeratosis verruciformis, and epidermal nevi.10

The condition can be treated with the diagnostic method itself (swabbing with alcohol) or with products such as salicylic-acid-based exfoliants or other keratolytic agents in order to accelerate the normalization of the skin.

We conclude that dermatosis neglecta should be taken into consideration because of its ability to mimic other skin diseases. This entity is much more common than the literature would lead one to believe. In particular, the appearance of hyperpigmented lesions with an unusual pattern should raise suspicion of dermatosis neglecta. In such cases, the alcohol swab test can be very useful.