An histological and ultrastructural study of the 'dirty neck' appearance in atopic eczema.

The 'dirty neck' appearance is a characteristic disorder of pigmentation, which has previously been found to affect approximately 2% of adult atopics. This disorder results in a rippled pattern of hyperpigmentation similar to that seen in macular amyloidosis. Biopsy specimens from affected skin of three patients were examined by histological and electron microscopical techniques. In addition to eczematous changes, marked pigmentary incontinence was observed. Amyloid-like material was detected by electron microscopy but not by light microscopy in all three specimens. Some deposition of amyloid occurs in this condition but the pigmentary changes are attributable to melanin incontinence. In 1987, two separate groups, Manabe et al. and Colver et al., described a distinctive type of hyperpigmentation, found particularly on the neck in some patients with chronic atopic eczema. Manabe's group found that 1.7% of 700 patients with atopic eczema showed this clinical characteristic, and that only adolescents and adults were affected. This condition has been called the 'dirty neck' appearance or 'ripple pigmentation of the neck in atopic dermatitis'. The clinical features are a rippled pattern of hyperpigmentation seen particularly on the anterior and lateral aspects of the neck (Fig. 1). We have also observed the same appearance in the inguinal areas. A number of factors could contribute to the development of hyperpigmentation in chronic atopic eczema. It is possible that the 'dirty neck' appearance is a form of post-inflammatory pigmentation due to previous eczema, ultraviolet exposure or even the application of photosensitizing products, and that the rippled appearance is related to the cutaneous anatomy of the neck. The pathogenesis of the 'dirty neck' is obscure, but in common with previous authors, we have noted that the rippled appearance of the hyperpigmentation resembles that seen in macular amyloidosis. In order to determine whether deposition of amyloid contributes to the development of this type of pigmentation in atopic dermatitis, an histological and ultrastructural examination of skin biopsies from three patients with the condition was undertaken.