Necrolytic acral erythema

Necrolytic Acral Erythema (NAE) is a rare skin disorder characterized by erythematous to violaceous, well-demarcated plaques that often exhibit scaling and crusting. The lesions predominantly affect the extremities, particularly the dorsal aspects of the hands and feet, and can lead to significant discomfort and morbidity. NAE is closely associated with Hepatitis C virus (HCV) infection, suggesting a pathogenetic link between the virus and the skin manifestations.

Etiology and Pathogenesis

The exact cause of Necrolytic Acral Erythema remains unclear, but it is strongly associated with Hepatitis C virus infection. The prevalence of HCV antibodies in patients with NAE is significantly higher than in the general population. It is hypothesized that the metabolic disturbances caused by HCV, particularly involving zinc and amino acid metabolism, play a crucial role in the pathogenesis of NAE. Additionally, there is evidence to suggest that the direct cytopathic effect of the virus on keratinocytes may contribute to the development of the lesions.

Clinical Features

NAE typically presents as painful, erythematous to violaceous plaques with well-defined borders. The lesions are often covered with a superficial scale and can progress to erosions or crusts. While NAE predominantly affects the dorsal aspects of the hands and feet, it can also involve other acral locations. Patients may report associated symptoms such as pruritus or burning sensations. The onset of NAE is insidious, and the disease course can be chronic and relapsing.

Diagnosis

The diagnosis of Necrolytic Acral Erythema is primarily clinical, supported by histopathological findings and the presence of HCV infection. Skin biopsy of an NAE lesion typically shows epidermal necrolysis, pallor of the upper epidermis, and a superficial perivascular lymphocytic infiltrate. Laboratory tests should include HCV serology to assess for underlying infection. Differential diagnosis includes other necrolytic erythemas, such as Necrolytic Migratory Erythema, psoriasis, and eczematous dermatitis, necessitating careful clinical and histological evaluation.

Treatment

Management of Necrolytic Acral Erythema focuses on treating the underlying HCV infection and symptomatic relief of the skin lesions. Antiviral therapy for HCV has been shown to lead to improvement or resolution of NAE in a significant number of cases. Topical treatments, including corticosteroids and emollients, may provide symptomatic relief. In cases where antiviral therapy is not feasible or effective, systemic treatments such as zinc supplementation and amino acid replacement may be considered, based on the proposed pathogenetic mechanisms.

Prognosis

The prognosis of Necrolytic Acral Erythema is closely tied to the treatment and control of the underlying HCV infection. With effective antiviral therapy, the skin lesions of NAE can significantly improve or resolve. However, in patients where HCV is not adequately controlled, NAE can persist or recur, leading to chronic skin disease and impacting quality of life.