Erythema Annulare Centrifugum and Other Figurate Erythemas



Erythema Annulare Centrifugum and Other Figurate Erythemas: Introduction




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Erythema Annulare Centrifugum at a Glance





  • Clinical pattern of annular expanding erythematous rings, which enlarge rapidly, fade, and then disappear, as new lesions appear.
  • Diagnosis of erythema annulare centrifugum is one of the exclusions.
  • Superficial and deep variants can be separated clinically and histologically. Deep form is usually lupus tumidus or erythema migrans.





The figurate erythemas include a variety of eruptions characterized by annular and polycyclic lesions. Classification of this group has always been controversial; the literature abounds with contradictions, uncertainties, and a bewildering array of synonyms. Darier in 1916 was the first to use the term erythema annulare centrifugum1 (EAC), although similar lesions had been described previously under other names. Table 43-1 lists the figurate erythemas and the differential diagnoses to consider.







Table 43-1 Migratory Erythemas 






Epidemiology





EAC is an uncommon disorder. No epidemiologic data are available. There are only three large series in the literature: (1) 66 cases identified clinically,2 (2) 73 first diagnosed histologically,3 and (3) 90 carrying either a clinical or histological diagnosis.4 EAC appears to have no predilection for either sex or for any age group.






Etiology and Pathogenesis





Both the annularity and the peripheral spread of EAC have attracted speculation as to a possible mechanism. Most hypotheses have centered on interactions among inflammatory cells, their mediators, and ground substance as foreign antigens diffuse through the skin.5,6






While many possible triggers have been suggested, all are common problems and EAC is very rare, so a direct causality is impossible to prove. It is better to view EAC as idiopathic. In one series, 24 patients were closely evaluated, and in none of the cases was any definite cause found.7 Suspected triggers include bacterial8 and candidal9 infections, autoimmune diseases,10 menses,11 pregnancy,12 and even stress.13 Although medications are often identified as causing EAC in case reports, none regularly induces such lesions. EAC may be coupled with malignant neoplasms, with the eruption disappearing after treatment of the tumor and often returning as the tumor recurs.1416 This paraneoplastic marker must be distinguished from metastatic tumors with an annular pattern.17,18






Clinical Findings





History



The history is most important in exploring the differential diagnostic considerations. In general, the lesions are asymptomatic but may be cosmetically disturbing.



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Jun 11, 2016 | Posted by in Dermatology | Comments Off on Erythema Annulare Centrifugum and Other Figurate Erythemas
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