title: New concepts on erythema annulare centrifugum: a clinical reaction pattern that does not represent a specific clinicopathological entity.
abstract: BACKGROUND
  Erythema annulare centrifugum (EAC) is considered an inflammatory skin disease with unknown aetiology. In most textbooks it is assigned to the incoherent conglomeration of figurate or gyrate erythemas.
  
  
  OBJECTIVE
  To re-evaluate a large cohort of patients with EAC and to assess the evidence for infection with Borrelia.
  
  
  METHODS
  We retrospectively investigated 90 cases with the diagnosis of EAC. Haematoxylin and eosin sections were re-examined and diagnoses were specified; these were then confirmed by clinicopathological correlation. Infection with Borrelia was assessed by focus-floating microscopy and by a Borrelia-specific polymerase chain reaction (PCR).
  
  
  RESULTS
  Besides a miscellaneous group of annular disorders at times confused with EAC such as urticaria, leucocytoclastic vasculitis and psoriasis (20 of 90; 22%), EAC appeared to serve as a collective term for three main clinicopathological reaction patterns: (i) (tumid) lupus erythematosus (29 of 90; 32%), (ii) spongiotic dermatitides (25 of 90; 28%) and (iii) pseudolymphoma (16 of 90; 18%). In 13 of 16 (81%) cases with a pseudolymphomatous reaction pattern spirochaetes stained positive but were negative in other reaction patterns of EAC as well as in negative controls. These findings were confirmed by a Borrelia-specific PCR which was positive in two of three (67%) of these pseudolymphomatous EAC cases but was negative in all other variants of EAC (none of five) as well as 20 controls.
  
  
  CONCLUSIONS
  We conclude that 'EAC' is a clinical reaction pattern that does not represent a specific clinicopathological entity and should lead to consideration of mainly lupus erythematosus, dermatitis and, in some cases, cutaneous Lyme disease.
authors: Department of Dermatology and Venereology, Friedrich-Schiller-University, Jena, Germany.
authors: M
authors: M
authors: Ziemer
authors: K
authors: K
authors: Eisendle
authors: B
authors: B
authors: Zelger
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001898:Borrelia / Q000302:isolation & purification; D001899:Borrelia Infections / Q000473:pathology*; D002648:Child; D003872:Dermatitis / Q000473:pathology*; D003937:Diagnosis, Differential; D004890:Erythema / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008178:Lupus Erythematosus, Cutaneous / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012189:Retrospective Studies; D012867:Skin / Q000473:pathology; D013987:Ticks / Q000382:microbiology; D055815:Young Adult