Erythema Annulare Centrifugum Workup

Updated: Sep 05, 2018
  • Author: Marisel Peralta-Abejo, MD, DPDS; Chief Editor: William D James, MD  more...
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Workup

Laboratory Studies

Skin scrapings from lesional sites of erythema annulare centrifugum (EAC) should be analyzed after preparation in potassium hydroxide (KOH) to ascertain the presence or the absence of hyphae suggestive of tinea or candidiasis.

Lyme antibody titer helps exclude erythema migrans.

An antinuclear antibody test should be performed in the appropriate clinical setting. Systemic lupus erythematosus is in the differential diagnosis of EAC, and Sjögren syndrome has been reported in association with EAC.

A purified protein derivative (PPD) test and an anergy panel can be used to help determine if an underlying M tuberculosis infection is present.

A complete blood count with differential can be used to evaluate a suspected underlying infection (neutrophilia with bacterial infection; eosinophilia with parasitic infection or hypereosinophilic syndrome).

If compatible with the clinical presentation of erythema annulare centrifugum, liver function studies may be useful because hyperbilirubinemia secondary to cholestasis and elevated transaminase levels secondary to hepatitis have been reported with EAC.

With an appropriate history of gastrointestinal complaints, a stool examination may be useful to search for ova and parasites (ascariasis has been reported with EAC).

For females, serum or urine beta-human chorionic gonadotropin testing may be indicated.

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Imaging Studies

Chest radiography can be used to exclude pulmonary nodules or hilar adenopathy suggestive of tuberculosis, malignancy (primary or metastatic), sarcoidosis, or lymphoma, all of which have been associated with erythema annulare centrifugum (EAC).

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Procedures

A skin punch biopsy may be performed on erythema annulare centrifugum (EAC) lesions.

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Histologic Findings

A biopsy is helpful in confirming a diagnosis of erythema annulare centrifugum (EAC). Two histologic subtypes exist: deep and superficial. In the classic or deep type, an intense, superficial and deep lymphocytic or lymphohistiocytic perivascular infiltrate in a coat-sleeve fashion is observed in the middle and lower dermis. No epidermal changes are observed. Clinically, these EAC lesions have indurated borders and are nonscaly and nonpruritic.

In the superficial type of EAC, a more nonspecific perivascular lymphohistiocytic infiltrate about the superficial dermal vessels and edema of the papillary dermis is present. The epidermal changes of parakeratosis and spongiosis may be present. Clinically, these lesions have a scale, may be pruritic, and may have vesiculations.

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