Figurate Erythemas

Published on 05/03/2015 by admin

Last modified 05/03/2015

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Figurate Erythemas

A number of cutaneous diseases can have an annular, arciform, or polycyclic configuration, from urticaria to granuloma annulare and tinea corporis (Table 15.1). Sites of involvement, rate of expansion, and characteristics of the border assist in narrowing the differential diagnosis, along with histologic examination of the active edge. This chapter discusses in more detail the classic figurate erythemas.

Table 15.1

Additional entities that can have an annular, arciform, or polycyclic configuration.

These disorders are covered in other chapters. See text for discussion of the classic figurate erythemas. Both erythema multiforme and erythema migrans can have a bull’s-eye appearance.

DIF, direct immunofluorescence; KOH, potassium hydroxide; LE, lupus erythematosus.

Erythema Annulare Centrifugum (EAC)

• Annular, arciform, and polycyclic plaques due to infiltrates of lymphocytes within the dermis; lesions usually last for a few weeks to months and as they migrate centrifugally, there is central clearing; recurrences are common.

• This gyrate erythema is sometimes divided into superficial and deep forms, based on clinicopathologic findings, with the superficial form being minimally elevated with “trailing” white scale (Fig. 15.1A) and the deep form having a more infiltrated border (Fig. 15.1B); some authors reserve the designation EAC for the superficial form.

Fig. 15.1 Erythema annulare centrifugum. A Superficial form, with polycyclic plaques and delicate scale on the inner margin of the advancing edge (trailing scale). The scale is detached centrally. B Deep form, with obvious elevation of advancing edges and without trailing scale.

• Color varies from pink to darker red-violet, with the superficial form favoring the thighs and deeper the trunk; peak incidence is during the fifth decade.

• Often idiopathic, but some cases appear to be a reactive process triggered by fungal infections, in particular tinea pedis, or less often, viral infections or medications.

• DDx: Tinea corporis (especially if scale is present); if no surface changes, annular urticaria (Fig. 15.2), benign lymphocytic infiltrate (of Jessner), cutaneous lymphoid hyperplasia, cutaneous lupus erythematosus (tumidus), and lymphoma cutis as well as the other entities covered in this chapter and Table 15.1; in some patients, the diagnosis of EAC is rendered after exclusion of other disorders.