Forum for Nordic Dermato-Venereology Nr 3, 2018 | Page 12

Educational Review Livedo Reticularis and Livedo Racemosa N icolas K luger , R egional E ditor , F inland Helsinki University Central Hospital and University of Helsinki, Dermatology, Allergology and Ve- nereology, FI-00029 Helsinki, Finland. E-mail: [email protected] This article is an update of a paper published in 2013 in Finska Läkaresällskapets Hand­ lingar (Kluger N. Hudsymtom som tecken på invärtes sjukdom: exemplet livedo hos vuxna. Finska Läkaresällskapets Handlingar 2013; 173: 23–28). Key-words: cutis marmorata; livedo racemosa; livedo reticularis. Livedo is a relatively common physical condition of the skin, consisting of macular, violaceous, connecting rings forming a netlike pattern. In most cases, livedo reticularis is completely benign, related to cold exposure. However, there are many other possible causes of livedo reticularis, and of livedo racemosa, which is a constant pathological livedo. Livedo may be a sign of a wide range of systemic/internal diseases, some of which are potentially life-threatening or may result in disabilities. Evaluation of a patient presenting with this finding is therefore extremely important. This paper provides clinicians with guidance regarding the evaluation of patients presenting with livedo. The term “livedo” describes a mottled, reticular, red-vio­ laceous, vascular discoloration of the skin. Livedo mainly affects the limbs, but it can be generalized. It is secondary to dysfunction of the dermal arteries or arterioles, with a re- duction or interruption of blood flow. This dysfunction may itself be related either to functional disorders (responsible for a vasospasm) or to organic disorders responsible for either an inflammation of the arteriolar wall (vasculitis) or a vascular obstruction (due to a thrombosis, an embolic event or vessel wall abnormalities) (1–3). The peculiar pattern of a livedo is due to the organization of the vascularization of the dermis (4). In brief, the arteriolar unit is a hexagon centred on an ascending capillary arteriole and surrounded by capillary venules (4). Livedo may be the first manifestation of a sys- temic/internal disease. Table I. Differential diagnoses of livedo in adults Reticulated dermatoses • Erythema ab igne • Quinidine photosensitisation • Reticulated erythematous mucinosis • Lichen planus • Lichenoid reactions (keratosis lichenoides chronica) • Confluent and reticulated papillomatosis (Gougerot-Carteaud syndrome) • Incontinentia pigmenti Hereditary cutaneous conditions with reticulated pigmentation • Xeroderma pigmentosum • Zinsser-Cole-Engman syndrome (congenital dyskeratosis) Poikilodermas • Hereditary: Rothmund-Thomson syndrome, Weary-Kindler Syndrome, Bloom syndrome: • Acquired: Parapsoriasis, discoid lupus, dermatomyositis, cutaneous Graft versus Host response, Civatte poikiloderma back (5, 6). Diagnosis is usually clinical. No biospy is needed to confirm the diagnosis. Differential diagnoses The first step in evaluation of a livedo or a so-called livedoid eruption is to rule out the differential diagnoses (Table I). The main differential diagnosis is erythema ab igne, a reticular, tel- angiectatic, pigmented dermatosis occurring after long-term exposure to infrared radiation that is insufficient to produce a burn (Fig. 1). It is usually located on heat exposed areas (fireplaces, hot-water bottles, heating pad, computer laptop or car heating system), chiefly on the lower limbs, thighs or 74 Fig. 1. Brown asymptomatic livedoid eruption of the thighs. Erythema ab igne. Forum for Nord Derm Ven 2018, Vol. 23, No. 3