P11 Acrodermatitis chronica atrophicans: a sign of late lyme disease

Abstract

Abstract Borrelia infection manifests a variety of signs and symptoms, and its insidiousness and heterogeneity mean that its diagnosis can be delayed. We describe two patients from south-east Scotland who presented with unilateral asymptomatic atrophic areas of skin discoloration. The first was a 71-year-old woman, who presented with a 4-month history of a nonprogressive, mottled, erythematous rash involving her right thigh, buttock and calf. Case 2 was a 56-year-old woman with a 2-year history of an erythematous area of atrophic skin involving the medial aspect of her left thigh and shin. Histology from case 1 showed a normal epidermis with a largely ‘top-heavy’ superficial and deep, predominantly interstitial and focally perivascular, lymphohistiocytic infiltrate, with a predominance of mononuclear histiocytes and with focal extension to deep reticular dermis. Scattered plasma cells were identified, but eosinophils were not a prominent feature. Well-formed granulomas were absent, as were interface dermatitic activity and vasculitic changes. On close questioning, each patient remembered ‘insect’ bites in the vicinity of the cutaneous changes, although neither recalled rashes that could have been consistent with erythema chronicum migrans. In both cases, serology confirmed infection with Borrelia burgdorferi (sensu lato) and diagnoses of acrodermatitis chronica atrophicans (ACA) were made. Both patients responded well to oral treatment with doxycycline. ACA is a cutaneous sign of late-stage Lyme disease and is caused by ongoing active skin infection by tick-borne bacteria of the Lyme disease group of Borrelia species. The tick bite has usually occurred months or years before symptom onset. Typically, there is an early, unilateral inflammatory stage with bluish-red discoloration of the skin and an oedematous appearance. This is followed by an atrophic stage where the skin becomes thin and wrinkled (‘cigarette paper’-like), with the loss of epidermal and dermal structures. Histological features usually include marked atrophy of the epidermis and dermis, loss of adnexal structures and an absence of elastic tissue. A band-like lymphocytic infiltration with plasma cells and mast cells is seen in the dermis, especially in the early stage of disease. Laboratory-confirmed cases of Lyme borreliosis in the UK have risen steadily since reporting began in 1986. ACA is likely to be underdiagnosed and, if there is a clinical suspicion, a detailed history, careful skin examination, Borrelia serology and skin biopsy should be undertaken. Early recognition and treatment reduce the risk of irreversible skin changes and systemic symptoms.