ERYTHEMA ANNULARE CENTRIFUGUM
Uncommon inflammatory hypersensitivity reaction characterized by annular or polycyclic plaques with central clearing and peripheral scale.
Favors the extremities and trunk.
Chronic condition that recurs and remits.
Two histologic variants: superficial variant consists of spongiosis, parakeratosis, hyperkeratosis or basal vacuolar changes with a perivascular infiltrate, and deep variant consists of perivascular lymphocytic infiltrate concentrated in the upper dermis without any epidermal changes.
Treatments include topical corticosteroids, vitamin D analogs, antibiotics, and antifungals.
The figurate or reactive erythemas encompass a variety of cutaneous eruptions that are characterized by erythematous lesions with annular, polycyclic, and/or arcuate configurations. The prototype of these disorders is erythema annulare centrifugum (EAC), which was a term first used by Darier in 1916 to describe an erythematous annular or polycyclic plaque that enlarged centrifugally with a trailing scale.1 The classification of EAC and other figurate erythemas is controversial, with some authors believing that the superficial and deep forms of EAC represent distinct clinical entities, and others considering EAC to be a clinical reaction pattern rather than a specific clinicopathologic entity.2
Although there is limited epidemiologic data on the prevalence of EAC, it is thought to be an uncommon disorder. Based on 4 clinicopathologic series in the literature that includes 202 patients, EAC exhibits no sex predilection and largely occurs in adults, with a peak incidence in the third and fourth decades.2-5 EAC also has been described in infants and children.6,7
EAC presents in the skin as a pink papule that expands centrifugally, forming an annular or polycyclic plaque with central clearing. In the superficial variant, lesions are slightly elevated and demonstrate desquamation at the inner margin, also referred to as a “trailing scale” (Figs. 46-1 and 46-2). The deep variant of EAC has an indurated, firm border, often without prominent scaling. The most common symptom associated with EAC is pruritus, although it is often asymptomatic. Residual scarring is uncommon, although postinflammatory hyperpigmentation may occur after lesions resolve. The most frequent sites of involvement of EAC are the buttocks, thighs, and trunk. In a series of 66 cases, the most common sites of involvement were the lower extremities (36 cases, 48%) and trunk (22 cases, 28%). Upper extremities and head and neck involvement were less common, observed in 12 cases (16%) and 6 cases (8%), respectively. When categorized by the extent of involvement, 28 patients (58%) had lesions located on only one site, 19 patients (28%) on 2 sites, and 9 patients (14%) had generalized disease with 3 or more sites.4
Superficial erythema annulare centrifugum. A large annular plaque with trailing scale behind the advancing erythematous edge.
Superficial erythema annulare centrifugum. Multiple lesions demonstrated epidermal changes with a ...