Abstract
In order to elucidate the pathogenesis and determine the adequate treatment for the so-called “dirty neck” that is seen in the patients with adult-type atopic dermatitis (AAD), we performed morphological and physiological studies of hyperpigmented lesions of the neck in 27 patients with AAD. Three patterns of hyperpigmentation were noted clinically: a) zebra-like b) diffuse, and c) intermediate. Of these three, zebra-like pigmentation was most peculiar and problematic for patients with AAD. Analyses of spectral reflectance and magnified images recorded with a digital camera and a videomicroscope revealed that the zebra-like hyperpigmentation consisted of less pigmented skin around hair follicles grouped in a necklace-like arrangement and dusky hyperpigmented belts with melanophage deposition between the hair follicles. A significant decrease in the conductance of the stratum corneum was found in patients with AAD when compared to that measured at the neck of normal subjects. Although one-year treatment with topical tacrolimus improved this damaged hydration capacity of the stratum corneum, no improvement in skin color (L* and a*) was achieved. However, we found a mildly positive correlation between duration of the disease and skin brightness (L*), indicating that this cosmetically troublesome hyperpigmentation will gradually improve if adequately treated.
