A 29-year-old white man presents with a 10-day history of a scaly, pruritic lesion on his right posterior thigh. His medical and family histories are unremarkable. On examination, the lesion is an annular erythematous plaque with trailing scale. The polycyclic plaque has a central clearing. Biopsy is performed, the results of which show a dense perivascular infiltrate and hyperkeratosis in the epidermis. Potassium hydroxide (KOH) test of the lesion is negative.
Submit your diagnosis to see full explanation.
Erythema annulare centrifugum (EAC), coined by Darier in 1916 and roughly translated as “centrifuged, ring-shaped redness,” is an uncommon chronic cutaneous eruption that presents as an outwardly expanding pink papule with an annular, arcuate, or polycyclic plaque.1 It is classified into a superficial variant, in which pruritic lesions have nonindurated borders and tend to desquamate, and a deep variant, in which lesions are typically nonpruritic and have firm, indurated borders without scaling.1,2 Limited epidemiologic data suggest that the condition can affect individuals of any race, sex, or age, but is seen with greater prevalence in adults, especially in the third and fourth decades of life.1
The etiology of EAC has not been elucidated, but it is thought that this condition is caused by a hypersensitivity reaction to infection, malignancy, systemic disease, medication, or pregnancy.1 In all of these cases, baseline physiology change is the recurring theme of disequilibrium in circulating immunologic factors or hormones. Therapeutic approaches to EAC have therefore attempted to target the underlying disequilibrium that leads to dermatologic sequelae. In cases of EAC linked to cancer, for example, treatment of the neoplasm is correlated with resolution of the skin lesions, while relapse is associated with recurrence.1
Of the infectious risk factors, superficial dermatophytoses such as tinea pedis, onychomycosis, and tinea corporis have been noted in up to 40% of patients with EAC.2 Other associated infectious agents include but are not limited to Candida, mycobacteria, Molluscipoxvirus, herpes zoster, Epstein-Barr virus, and HIV.1,3 EAC can also present as a component of a paraneoplastic syndrome preceding the diagnosis of lymphoproliferative malignancies, breast carcinoma, and other cancers2,4,5 or as a concurrent condition in patients with liver, endocrine, or autoimmune disease.2,6
Induction of EAC has been reported with numerous drugs — including finasteride, azacitidine, rituximab, ustekinumab, amitriptyline, gold sodium thiomalate, and ribavirin and pegylated interferon-α2a indicated for hepatitis C — with discontinuation of the drug leading to resolution of dermatologic symptoms.1 In addition, expectant mothers in the second and third trimesters of pregnancy have presented with EAC, albeit rarely; the lesions gradually fade shortly after delivery.1,7
The classic presentation of EAC is a patient who developed a pink papule on the buttock, thigh, or trunk that evolved into a larger plaque that has a lighter center with pronounced borders.1,2 While the diagnosis of EAC is primarily clinical, annular lesions that appear similar to it may be differentiated by histopathologic examination, particularly if they recur or are resistant to treatment. Classically, a dense infiltrate of lymphocytes, histiocytes, and eosinophils is distributed in a “coat-sleeve” pattern wrapped tightly around blood vessels.1 In the superficial type of EAC, changes are primarily restricted to the epidermal or upper dermal layers and may involve hyperkeratosis, parakeratosis, spongiosis, or vacuolar degeneration.1 In contrast, the deep type of EAC is associated with perivascular infiltrates along vascular plexuses in the upper and lower dermis with minimal, if any, disruption of the epidermis.1
The differential diagnosis of EAC includes infectious conditions such as erythema chronicum migrans (Lyme borreliosis) and tinea corporis, other hypersensitivity conditions such as annular urticaria and erythema multiforme, chronic conditions such as annular subacute cutaneous lupus erythematosus and annular psoriasis, and malignancies such as mycosis fungoides.1 Due to its unknown etiology and lack of distinctive clinical features, EAC is often regarded as a diagnosis of exclusion. A thorough and detailed patient history along with clinical findings should help eliminate other pathologies from the differential. In patients with a known or suspected diagnosis of infection, malignancy, or systemic disease, a full diagnostic workup should be performed to identify and optimize the management of underlying conditions that might precipitate the appearance of EAC. For patients who have recently started treatment with medications with reported associations to EAC, one should consider either alternative pharmacotherapies or symptomatic treatment of the skin lesion if the therapeutic benefit of the medication in question outweighs its dermatologic side effects. Pregnant patients presenting with EAC should be counseled regarding the natural progression and resolution of the disease, which is typically considered sufficient treatment due to the expected resolution of symptoms after delivery.1,7
In the absence of any risk factors or associated disease, EAC tends to follow a waxing-waning cycle in severity and may eventually disappear spontaneously.1,2 In a retrospective review, the duration of disease was found to be approximately 2.8 years, with continuous lesions averaging 4.75 months.1,2 The superficial type of EAC tends to be more resistant to treatment and recurs at a higher rate, whereas exacerbations of the deep type tend to be of longer duration.1 Most treatments are targeted at symptomatic relief, rather than shortening the trajectory of the illness. Topical corticosteroids, topical vitamin D analogs, and oral antihistamines may be prescribed to alleviate pruritus. Oral steroids have been shown to fade plaques; however, rebound recurrence of EAC can occur with sudden cessation of treatment.1,2 More recently, antifungal agents and antibiotics including fluconazole, erythromycin, and metronidazole have demonstrated substantial benefit in a limited number of case studies.1,8-10 The paucity of robust clinical data suggests that one should only consider these treatment options if EAC is believed to be secondary to an underlying infectious cause or if the lesion has been resistant to other therapies.
The patient in the case described decided against therapy, and his rash resolved after 6 months with supportive care
Christopher Wong, BA, and Eleanor Johnson, BA, are medical students at Baylor College of Medicine, and Christopher Rizk, MD, is a dermatologist at Elite Dermatology in Houston, Texas.
1. Ahn CS, Huang WW. Erythema annulare centrifugum and other figurate erythemas. In: Kang S, Amagai M, Bruckner AL, et al, eds. Fitzpatrick’s Dermatology. 9th ed. New York, NY: McGraw-Hill; 2019.
2. Kim KJ, Chang SE, Choi JH, Sung KJ, Moon KC, Koh JK. Clinicopathologic analysis of 66 cases of erythema annulare centrifugum. J Dermatol. 2002;29(2):61-67.
3. Chu C-H, Tuan P-K, Yang S-J. Molluscum contagiosum-induced erythema annulare centrifugum. JAMA Dermatol. 2015;151(12):1385-1386.
4. Chodkiewicz HM, Cohen PR. Paraneoplastic erythema annulare centrifugum eruption: PEACE. Am J Clin Dermatol. 2012;13(4):239-246.
5. Topal IO, Topal Y, Sargan A, et al. Erythema annulare centrifugum as presenting sign of activation of breast cancer. An Bras Dermatol. 2015;90(6):925-927.
6. Chander R, Yadav P, Singh A, Nangia A. Systemic lupus erythematosus presenting as erythema annulare centrifugum. Lupus. 2014;23(11):1197-1200.
7. Chiang CH, Lai F-J. Pregnancy-associated erythema annulare centrifugum. J Formos Med Assoc. 2015;114(7):670-671.
8. Kruse LL, Kenner-Bell BM, Mancini AJ. Pediatric erythema annulare centrifugum treated with oral fluconazole: a retrospective series. Pediatr Dermatol. 2016;33(5):501-506.
9. Chuang F-C, Lin S-H, Wu W-M. Erythromycin as a safe and effective treatment option for erythema annulare centrifugum. Indian J Dermatol. 2015;60(5):519.
10. De Aloe G, Rubegni P, Risulo M, Sbano P, Poggiali S, Fimiani M. Erythema annulare centrifugum successfully treated with metronidazole. Clin Exp Dermatol. 2005;30(5):583-584.