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Effectiveness of Topical Adapalene in Dowling-Degos Disease

1999; Karger Publishers; Volume: 198; Issue: 2 Linguagem: Inglês

10.1159/000018102

1421-9832

G. F. Altomare, Giovanni Luigi Capella, Claudio Fracchiolla, E. Frigerio,

Genetic and rare skin diseases.

The clinical aspect of Dowling-Degos disease (DDD) is clearly summarized in the descriptive denomination 'reticulate pigmented anomaly of the flexures'. DDD is a harmless but esthetically disfiguring, slowly evolving pigmentation of the great skin folds with a reticulate follicular pattern. This follicular pattern can be very pronounced so that in some cases the acronym DDD should more appropriately mean 'dark dot disease' [1]; this last term refers to the presence of typical comedo-like, black pinhead-sized hyperkeratotic follicular lesions [1]. The condition affects mainly women, and it is believed to be a genetically determined disease with an autosomal dominant inheritance [2], although many cases appear to be sporadic [3], probably because of low penetrance or incomplete pedigree inquiry. The available literature documents the relation of this syndrome with other rare pigmentary abnormalities. However, the therapeutic aspect seems to have been so far disregarded. We report a woman with an overt pruritic form of DDD successfully treated with the application of adapalene. To the best of our knowledge, this is the first report of a satisfying medical therapeutic attempt in DDD.A 76-year-old woman was admitted with a papular follicular hyperpigmentation of submammary, intergluteal and groin flexures (fig. 1). The pigmentary plaques were studded with comedo-like lesions. The eruption had been lasting for 1 year and was intensely itchy. Palmar or facial pits, breaks in epidermal ridge pattern and adenitis of apocrine glands were absent. None of the patient's relatives was affected. The disorder had previously been labeled flexural Darier's disease, acanthosis nigricans and postinflammatory hyperpigmentation. Former treatments included topical steroids, antibiotics and antimycotics, and oral etretinate (25 mg b.i.d. for 3 months), all of which had proven ineffective. Laboratory investigations, including tests for endocrine functions, were normal. The patient was neither obese nor hypertensive. A biopsy was performed. The histological examination showed focal parakeratotic plugs obstructing follicular infundibula, irregular acanthosis, elongation of rete ridges and basal hyperpigmentation with a normal number of melanocytes. A sparse perivascular mixed round cell infiltrate was present. The clinical diagnosis of DDD was confirmed. Topical treatment with adapalene gel 0.1% b.i.d. was started, and after only 5 days of treatment the patient's condition was as shown in figure 2. Further improvement, including suppression of itching and further clearing of the dark and deeper reticulum still evident in figure 2, has ensued from the continuous application of adapalene, which however cannot be discontinued because of prompt relapse.DDD is a rare, well-defined disturbance of epidermal proliferation [4], possibly reactive to a primary retention and/or overproduction of melanin [1, 5]. The exact nosographic position of DDD is controversial, and this entity is thought to be related to other rare conditions such as reticulate acropigmentation of Kitamura, Haber's syndrome, pigmentatio reticularis faciei et colli with epithelial cystomatosis, familial multiple follicular hamartoma [6], acropigmentation of Dohi and dyschromatosis universalis hereditaria [7], all of which share some clinical or histological aspects with DDD [6, 7]. Indeed, there seems to be a general agreement towards a 'spectrum hypothesis' [6, 8]regarding all these syndromes as the result of a 'nosographical splitting' of a single underlying mixed genetic disorder [7, 8]. Some differences are merely topographical: for instance, facial pits are described in true DDD [9], while palmar pits are more typical of the Kitamura form [10]. DDD can be associated with hidradenitis suppurativa, probably because of follicular occlusion [11]. The clinical variability of DDD itself must be stressed, because the expression of the condition can range from isolated thin reticulate pigmentation to gross hyperchromia with overt follicular comedo-like lesions [1], as in our case. The great flexures are typically attained, but DDD can also involve the neck and the genitalia [1]as well as the scalp [9].Because DDD is a genetically determined disease [2], only symptomatic therapies can be tried. Depigmentating agents such as hydroquinone are disappointing [1]. Some authors claim the efficacy of laser therapy (copper vapor or Q-switched Nd: YAG) [3]. A therapeutic attempt with etretinate was ineffective [4], and this has also been confirmed by our case. Local application of tretinoin is already known to be nonfeasible, because of its irritative effect favoring erosions [4]. In this view, we decided to try adapalene, a naphthoic acid derivative with recognized retinoid-like pharmacology, because of its comedolytic [12]and regulatory effect on epidermal proliferation and differentiation [13]. Moreover, adapalene has a low skin irritation potential and displays anti-inflammatory properties [14]that make it suitable for application in intertriginous areas. Results do not need any other comment than the figures illustrating them. Treatment with adapalene can be protracted for a long time, as commonly done in acneic patients. Thus, we conclude that adapalene is to be regarded as the current provisional treatment of choice for the occasional patient with DDD. Further studies are needed to confirm our observation.