Atopic dirty neck or acquired atopic hyperpigmentation? An epidemiological and clinical study from the National Skin Centre in Singapore.

Background: 'Atopic dirty neck' is a poorly understood acquired hyperpigmentation in patients with atopic dermatitis (AD).

Objective: To report a single-centre experience with synthesis of this entity's features.

Methods: All patients with AD with dirty neck seen over a 5-month period at the National Skin Centre were invited to participate.

Results: Out of 544 AD patients examined, 78 (14.3%) had acquired pigmentation of the neck. The majority had moderate-to-severe underlying eczema. Histopathology showed increased epidermal melanin and dermal melanophages, a thickened basement membrane and a dense superficial perivascular infiltrate.

Conclusion: Acquired atopic hyperpigmentation has a high prevalence, particularly in adolescent Asian males. Clinico-pathological correlation suggests it results from both frictional melanosis and post-inflammatory hyperpigmentation. The rippled appearance and the onset in adolescence are probably due to accentuation of the juxta-clavicular beaded lines. Optimal control of eczema may improve and potentially prevent the development, which is of importance considering the psychosocial impact of the condition.